Publications

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the acinetobacter outer membrane contains multiple specific channels for carbapenem β-lactams as revealed by kinetic characterization analyses of imipenem permeation into acinetobacter baylyi cells.the number and type of outer membrane (om) channels responsible for carbapenem uptake in acinetobacter are still not well defined. here, we addressed these questions by using acinetobacter baylyi as a model species and a combination of methodologies aimed to characterize om channels in their original membrane environment. kinetic and competition analyses of imipenem (ipm) uptake by a. baylyi whole cells allowed us to identify different carbapenem-specific om uptake sites. comparative analyses of ...201728069648
growth and wax ester production of an acinetobacter baylyi adp1 mutant deficient in exopolysaccharide capsule synthesis.acinetobacter baylyi adp1 naturally produces wax esters that could be used as a raw material in industrial applications. we attempted to improve wax ester yield of a. baylyi adp1 by removing rmla, a gene involved in exopolysaccharide production. growth rate, biomass formation and wax ester yield on 4-hydroxybenzoate were not affected, but the rmla (-) strain grew slower on acetate, while reaching similar biomass and wax ester yield. the rmla (-) cells had malformed shape and large size and grew ...201727866334
evaluation of thioesterases from acinetobacter baylyi for production of free fatty acids.acinetobacter baylyi is one of few gram-negative bacteria capable of accumulating storage lipids in the form of triacylglycerides and wax esters, which makes it an attractive candidate for production of lipophilic products, including biofuel precursors. thioesterases play a significant dual role in the triacylglyceride and wax ester biosynthesis by either providing or removing acyl-coa from this pathway. therefore, 4 different thioesterase genes were cloned from acinetobacter baylyi adp1 and exp ...201728335611
twin-layer biosensor for real-time monitoring of alkane metabolism.intracellular metabolic sensors can be used for efficient screening and optimization of microbial cell factories. in particular, the sensors are useful in acquiring information about pathway dynamics and bottlenecks in a straightforward manner. here, we developed a twin-layer biosensor which functions simultaneously at two levels: through transcription factor mediated sensing and enzyme-metabolite interaction, providing insights into the dynamics of alkane metabolism. in addition, the sensor can ...201728333269
quantification of chemotaxis-related alkane accumulation in acinetobacter baylyi using raman microspectroscopy.alkanes are one of the most widespread contaminants in the natural environment, primarily as a consequence of biological synthesis and oil spills. many indigenous microbes metabolize alkanes, and the chemotaxis and accumulation in some strains has been identified. for the first time, we apply raman microspectroscopy to identify such chemotaxis-related affinity, and quantify the alkane concentrations via spectral alterations. raman spectral alterations were only found for the alkane chemo-attract ...201728256129
costs and benefits of natural transformation in acinetobacter baylyi.natural transformation enables acquisition of adaptive traits and drives genome evolution in prokaryotes. yet, the selective forces responsible for the evolution and maintenance of natural transformation remain elusive since taken-up dna has also been hypothesized to provide benefits such as nutrients or templates for dna repair to individual cells.201728202049
identification of a novel epoxyqueuosine reductase family by comparative genomics.the reduction of epoxyqueuosine (oq) is the last step in the synthesis of the trna modification queuosine (q). while the epoxyqueuosine reductase (ec 1.17.99.6) enzymatic activity was first described 30 years ago, the encoding gene queg was only identified in escherichia coli in 2011. interestingly, queg is absent from a large number of sequenced genomes that harbor q synthesis or salvage genes, suggesting the existence of an alternative epoxyqueuosine reductase in these organisms. by analyzing ...201728128549
characterization of five fatty aldehyde dehydrogenase enzymes from marinobacter and acinetobacter: structural insights into the aldehyde binding pocket.enzymes involved in lipid biosynthesis and metabolism play an important role in energy conversion and storage, and in the function of structural components such as cell membranes. the fatty aldehyde dehydrogenase (falddh) plays a central function in the metabolism of lipid intermediates, oxidizing fatty aldehydes to the corresponding fatty acid, and competing with pathways that would further reduce the fatty aldehydes to fatty alcohols or require the fatty aldehydes to produce alkanes. in this r ...201728389542
identification of unique cardiolipin and monolysocardiolipin species in acinetobacter baumannii.acidic glycerophospholipids play an important role in determining the resistance of gram-negative bacteria to stress conditions and antibiotics. acinetobacter baumannii, an opportunistic human pathogen which is responsible for an increasing number of nosocomial infections, exhibits broad antibiotic resistances. here lipids of a. baumannii have been analyzed by combined maldi-tof/ms and tlc analyses; in addition gc-ms analyses of fatty acid methyl esters released by methanolysis of membrane phosp ...201728592862
new naphthalene whole-cell bioreporter for measuring and assessing naphthalene in polycyclic aromatic hydrocarbons contaminated site.a new naphthalene bioreporter was designed and constructed in this work. a new vector, pwh1274_nah, was constructed by the gibson isothermal assembly fused with a 9 kb naphthalene-degrading gene nahad (nahaa nahab nahac nahad nahb nahf nahc nahq nahe nahd) and cloned into acinetobacter adpwh_lux as the host, capable of responding to salicylate (the central metabolite of naphthalene). the adpwh_nah bioreporter could effectively metabolize naphthalene and evaluate the naphthalene in natural water ...201728810221
succinate, iron chelation, and monovalent cations affect the transformation efficiency of acinetobacter baylyi strain atcc33305 during growth in complex media.natural transformation is the acquisition of new genetic material via the uptake of exogenous dna by competent bacteria. acinetobacter baylyi is model for natural transformation. here we focus on natural transformation of a. baylyi strain atcc33305 grown in complex media and seek environmental conditions that appreciably affect transformation efficiency. we find that the transformation efficiency for a. baylyi is a resilient characteristic that remains high under most conditions tested. we do fi ...201728772085
the role of core and accessory type iv pilus genes in natural transformation and twitching motility in the bacterium acinetobacter baylyi.here we present an examination of type iv pilus genes associated with competence and twitching in the bacterium acinetobacter baylyi (strain adp1, bd413). we used bioinformatics to identify potential competence and twitching genes and their operons. we measured the competence and twitching phenotypes of the bioinformatically-identified genes. these results demonstrate that competence and twitching in a. baylyi both rely upon a core of the same type iv pilus proteins. the core includes the inner ...201728771515
genomic and physiological characterization of a laboratory-isolated acinetobacter schindleri ace strain that quickly and efficiently catabolizes acetate.an acinetobacter strain, designated ace, was isolated in the laboratory. phylogenetic tests and average nucleotide identity value comparisons suggested that ace belongs to the species acinetobacterschindleri. we report for the first time the complete genome sequence of an a. schindleri strain, which consists of a single circular chromosome of 3 001 209 bp with an overall dna g+c content of 42.9 mol% and six plasmids that account for 266 844 bp of extrachromosomal material. the presence or absenc ...201728671531
reduced mutation rate and increased transformability of transposon-free acinetobacter baylyi adp1-isx.the genomes of most bacteria contain mobile dna elements that can contribute to undesirable genetic instability in engineered cells. in particular, transposable insertion sequence (is) elements can rapidly inactivate genes that are important for a designed function. we deleted all six copies of is1236 from the genome of the naturally transformable bacterium acinetobacter baylyi adp1. the natural competence of adp1 made it possible to rapidly repair deleterious point mutations that arose during s ...201728667117
production of long chain alkyl esters from carbon dioxide and electricity by a two-stage bacterial process.microbial electrosynthesis (mes) is a promising technology for the reduction of carbon dioxide into value-added multicarbon molecules. in order to broaden the product profile of mes processes, we developed a two-stage process for microbial conversion of carbon dioxide and electricity into long chain alkyl esters. in the first stage, the carbon dioxide is reduced to organic compounds, mainly acetate, in a mes process by sporomusa ovata. in the second stage, the liquid end-products of the mes proc ...201728651136
enhancing multiplex genome editing by natural transformation (mugent) via inactivation of ssdna exonucleases.recently, we described a method for multiplex genome editing by natural transformation (mugent). mutant constructs for mugent require large arms of homology (>2000 bp) surrounding each genome edit, which necessitates laborious in vitro dna splicing. in vibrio cholerae, we uncover that this requirement is due to cytoplasmic ssdna exonucleases, which inhibit natural transformation. in ssdna exonuclease mutants, one arm of homology can be reduced to as little as 40 bp while still promoting integrat ...201728575400
malonate degradation in acinetobacter baylyi adp1: operon organization and regulation by mdcr.transcriptional regulators in the lysr or gntr families are typically encoded in the genomic neighbourhood of bacterial genes for malonate degradation. while these arrangements have been evaluated using bioinformatics methods, experimental studies demonstrating co-transcription of predicted operons were lacking. here, transcriptional regulation was characterized for a cluster of mdc genes that enable a soil bacterium, acinetobacter baylyi adp1, to use malonate as a carbon source. despite previou ...201728537542
degradation of extracellular antibiotic resistance genes with uv254 treatment.disinfected wastewater effluent contains a complex mixture of biomolecules including dna. if intact genes conveying antibiotic resistance survive the disinfection process, environmental bacteria may take them up. we treated plasmid pwh1266, which contains ampicillin resistance gene blatem-1 and tetracycline resistance gene teta, with uv254 doses up to 430 mj/cm(2) and studied the ability of those genes to be acquired by acinetobacter baylyi. the plasmids required approximately 20-25 mj/cm(2) per ...201728475324
biosynthesis of the fatty acid isopropyl esters by engineered escherichia coli.the fatty acid methyl esters and fatty acid ethyl esters are known as biodiesels which are considered to be renewable, nontoxic and biodegradable biofuels. however, the conventional biodiesels show a high crystallization temperature which is one of the most critical obstacles against the widespread biodiesel usage. the high crystallization temperature of biodiesel can be reduced by replacing the methyl or ethyl ester with an isopropyl moiety. here we report on a strategy to establish biosynthesi ...201728465060
substitutions of short heterologous dna segments of intragenomic or extragenomic origins produce clustered genomic polymorphisms.in a screen for unexplained mutation events we identified a previously unrecognized mechanism generating clustered dna polymorphisms such as microindels and cumulative snps. the mechanism, short-patch double illegitimate recombination (spdir), facilitates short single-stranded dna molecules to invade and replace genomic dna through two joint illegitimate recombination events. spdir is controlled by key components of the cellular genome maintenance machinery in the gram-negative bacterium acineto ...201627956618
no effect of natural transformation on the evolution of resistance to bacteriophages in the acinetobacter baylyi model system.the adaptive benefits of natural transformation, the active uptake of free dna molecules from the environment followed by incorporation of this dna into the genome, may be the improved response to selection resulting from increased genetic variation. drawing analogies with sexual reproduction, transformation may be particularly beneficial when selection rapidly fluctuates during coevolution with virulent parasites ('the red queen hypothesis'). here we test this hypothesis by experimentally evolv ...201627869203
privatization of cooperative benefits stabilizes mutualistic cross-feeding interactions in spatially structured environments.metabolic cross-feeding interactions are ubiquitous in natural microbial communities. however, it remains generally unclear whether the production and exchange of metabolites incurs fitness costs to the producing cells and if so, which ecological mechanisms can facilitate a cooperative exchange of metabolites among unrelated individuals. we hypothesized that positive assortment within structured environments can maintain mutualistic cross-feeding. to test this, we engineered acinetobacter baylyi ...201626623546
phosphinothricin acetyltransferases identified using in vivo, in vitro, and bioinformatic analyses.acetylation of small molecules is widespread in nature, and in some cases, cells use this process to detoxify harmful chemicals. streptomyces species utilize a gcn5 n-acetyltransferase (gnat), known as bar, to acetylate and detoxify a self-produced toxin, phosphinothricin (ppt), a glutamate analogue. bar homologues, such as mdda from salmonella enterica, acetylate methionine analogues such as methionine sulfoximine (msx) and methionine sulfone (mso), but not ppt, even though bar homologues are a ...201627694229
reverse and multiple stable isotope probing to study bacterial metabolism and interactions at the single cell level.the interactions between microorganisms driven by substrate metabolism and energy flow are important to shape diversity, abundance, and structure of a microbial community. single cell technologies are useful tools for dissecting the functions of individual members and their interactions in microbial communities. here, we developed a novel raman stable isotope probing (raman-sip), which uses raman microspectroscopy coupled with reverse and d2o colabeling to study metabolic interactions in a two-s ...201627588325
novel heterologous bacterial system reveals enhanced susceptibility to dna damage mediated by yqgf, a nearly ubiquitous and often essential gene.despite its presence in most bacteria, yqgf remains one of only 13 essential genes of unknown function in escherichia coli. predictions of yqgf function often derive from sequence similarity to ruvc, the canonical holliday junction resolvase. to clarify its role, we deleted yqgf from a bacterium where it is not essential, acinetobacter baylyi adp1. loss of yqgf impaired growth and increased the frequency of transformation and allelic replacement (tar). when e. coli yqgf was inserted in place of ...201627527105
role of wax ester synthase/acyl coenzyme a:diacylglycerol acyltransferase in oleaginous streptomyces sp. strain g25.recently, we isolated a novel streptomyces strain which can accumulate extraordinarily large amounts of triacylglycerol (tag) and consists of 64% fatty acids (dry weight) when cultivated with glucose and 50% fatty acids (dry weight) when cultivated with cellobiose. to identify putative gene products responsible for lipid storage and cellobiose utilization, we analyzed its draft genome sequence. a single gene encoding a wax ester synthase/acyl coenzyme a (coa):diacylglycerol acyltransferase (ws/d ...201627474711
bioluminescence-based system for rapid detection of natural transformation.horizontal gene transfer plays a significant role in bacterial evolution and has major clinical importance. thus, it is vital to understand the mechanisms and kinetics of genetic transformations. natural transformation is the driving mechanism for horizontal gene transfer in diverse genera of bacteria. our study introduces a simple and rapid method for the investigation of natural transformation. this highly sensitive system allows the detection of a transformation event directly from a bacteria ...201627190150
experimental and metabolic modeling evidence for a folate-cleaving side-activity of ketopantoate hydroxymethyltransferase (panb).tetrahydrofolate (thf) and its one-carbon derivatives, collectively termed folates, are essential cofactors, but are inherently unstable. while it is clear that chemical oxidation can cleave folates or damage their pterin precursors, very little is known about enzymatic damage to these molecules or about whether the folate biosynthesis pathway responds adaptively to damage to its end-products. the presence of a duplication of the gene encoding the folate biosynthesis enzyme 6-hydroxymethyl-7,8-d ...201627065985
osmotic stress response in acinetobacter baylyi: identification of a glycine-betaine biosynthesis pathway and regulation of osmoadaptive choline uptake and glycine-betaine synthesis through a choline-responsive beti repressor.acinetobacter baylyi, a ubiquitous soil bacterium, can cope with high salinity by uptake of choline as precursor of the compatible solute glycine betaine. here, we report on the identification of a choline dehydrogenase (beta) and a glycine betaine aldehyde dehydrogenase (betb) mediating the oxidation of choline to glycine betaine. the betab genes were found to form an operon together with the potential transcriptional regulator beti. the transcription of the betiba operon and the two recently i ...201626910138
emergence of a competence-reducing filamentous phage from the genome of acinetobacter baylyi adp1.bacterial genomes commonly contain prophage sequences as a result of past infections with lysogenic phages. many of these integrated viral sequences are believed to be cryptic, but prophage genes are sometimes coopted by the host, and some prophages may be reactivated to form infectious particles when cells are stressed or mutate. we found that a previously uncharacterized filamentous phage emerged from the genome of acinetobacter baylyi adp1 during a laboratory evolution experiment. this phage ...201627645387
umudab: an error-prone polymerase accessory homolog whose n-terminal domain is required for repression of dna damage inducible gene expression in acinetobacter baylyi.in many bacteria, the dna damage response induces genes (sos genes) that were repressed by lexa. lexa represses transcription by binding to sos promoters via a helix-turn-helix motif in its n-terminal domain (ntd). upon dna damage, lexa cleaves itself and allows induction of transcription. in acinetobacter baumannii and acinetobacter baylyi, multiple genes are induced by dna damage, and although the acinetobacter genus lacks lexa, a homolog of the error-prone polymerase subunit umud, called umud ...201627010837
identification and characterization of two new 5-keto-4-deoxy-d-glucarate dehydratases/decarboxylases.hexuronic acids such as d-galacturonic acid and d-glucuronic acid can be utilized via different pathways within the metabolism of microorganisms. one representative, the oxidative pathway, generates α-keto-glutarate as the direct link entering towards the citric acid cycle. the penultimate enzyme, keto-deoxy glucarate dehydratase/decarboxylase, catalyses the dehydration and decarboxylation of keto-deoxy glucarate to α-keto-glutarate semialdehyde. this enzymatic reaction can be tracked continuous ...201627855668
metabolic engineering of acinetobacter baylyi adp1 for removal of clostridium butyricum growth inhibitors produced from lignocellulosic hydrolysates.pretreatment of lignocellulosic biomass can produce inhibitory compounds that are harmful for microorganisms used in the production of biofuels and other chemicals from lignocellulosic sugars. selective inhibitor removal can be achieved with biodetoxification where microorganisms catabolize the inhibitors without consuming the sugars. we engineered the strictly aerobic acinetobacter baylyi adp1 for detoxification of lignocellulosic hydrolysates by removing the gene for glucose dehydrogenase, gcd ...201526628912
osmotic stress response in acinetobacter baylyi: identification of a glycine-betaine biosynthesis pathway and regulation of osmoadaptive choline uptake and glycine betaine synthesis through a choline-responsive beti repressor.acinetobacter baylyi, a ubiquitous soli bacterium, can cope with high salinity by uptake of choline as precursor of the compatible solute glycine betaine. here we report on the identification of a choline dehydrogenase (beta) and a glycine betaine aldehyde dehydrogenase (betb) mediating the oxidation of choline to glycine betaine. the betab genes were found to form an operon together with the potential transcriptional regulator beti. the transcription of the betiba operon and the two recently id ...201526626502
assessment of bacterial acyltransferases for an efficient lipid production in metabolically engineered strains of e. coli.microbially produced lipids like triacylglycerols or fatty acid ethyl esters are currently of great interest as fuel replacements or other industrially relevant compounds. they can even be produced by non-oleaginous microbes, like escherichia coli, upon metabolic engineering. however, there is still much room for improvement regarding the yield for a competitive microbial production of lipids or biofuels. we genetically engineered e. coli by expressing fadd, fadr, pgpb, plsb and 'tesa in combina ...201526460058
phage t4-induced dna breaks activate a trna repair-defying anticodon nuclease.the natural role of the conserved bacterial anticodon nuclease (acnase) rloc is not known, but traits that set it apart from the homologous phage t4-excluding acnase prrc could provide relevant clues. prrc is silenced by a genetically linked dna restriction-modification (rm) protein and turned on by a phage-encoded dna restriction inhibitor. in contrast, rloc is rarely linked to an rm protein, and its acnase is regulated by an internal switch responsive to double-stranded dna breaks. moreover, p ...201526031711
genome assembly using nanopore-guided long and error-free dna reads.long-read sequencing technologies were launched a few years ago, and in contrast with short-read sequencing technologies, they offered a promise of solving assembly problems for large and complex genomes. moreover by providing long-range information, it could also solve haplotype phasing. however, existing long-read technologies still have several limitations that complicate their use for most research laboratories, as well as in large and/or complex genome projects. in 2014, oxford nanopore rel ...201525927464
growth phase-specific evolutionary benefits of natural transformation in acinetobacter baylyi.natural transformation in bacteria facilitates the uptake and genomic integration of exogenous dna. this allows horizontal exchange of adaptive traits not easily achieved by point mutations, and has a major role in the acquisition of adaptive traits exemplified by antibiotic resistance determinants and vaccination escape. mechanisms of dna uptake and genomic integration are well described for several naturally transformable bacterial species; however, the selective forces responsible for its evo ...201525848876
erratum to: use of a whole-cell bioreporter, acinetobacter baylyi, to estimate the genotoxicity and bioavailability of chromium(vi)-contaminated soils. 201525725633
metabolic cross-feeding via intercellular nanotubes among bacteria.bacteria frequently exchange metabolites by diffusion through the extracellular environment, yet it remains generally unclear whether bacteria can also use cell-cell connections to directly exchange nutrients. here we address this question by engineering cross-feeding interactions within and between acinetobacter baylyi and escherichia coli, in which two distant bacterial species reciprocally exchange essential amino acids. we establish that in a well-mixed environment e. coli, but likely not a. ...201525703793
genome instability mediates the loss of key traits by acinetobacter baylyi adp1 during laboratory evolution.acinetobacter baylyi adp1 has the potential to be a versatile bacterial host for synthetic biology because it is naturally transformable. to examine the genetic reliability of this desirable trait and to understand the potential stability of other engineered capabilities, we propagated adp1 for 1,000 generations of growth in rich nutrient broth and analyzed the genetic changes that evolved by whole-genome sequencing. substantially reduced transformability and increased cellular aggregation evolv ...201525512307
unusual features of the sequences of copies of the 16s-23s rrna internal transcribed spacer regions of acinetobacter bereziniae, acinetobacter guillouiae and acinetobacter baylyi arise from horizontal gene transfer events.the highly variable nature of the internal transcribed spacer region (its) has been claimed to represent an ideal target for designing species-specific probes/primers capable of differentiating between closely related acinetobacter species. however, several acinetobacter species contain multiple its copies of variable lengths, and these include acinetobacter bereziniae, acinetobacter guillouiae and acinetobacter baylyi. this study shows these length variations result from inter-genomic insertion ...201525505188
use of a whole-cell bioreporter, acinetobacter baylyi, to estimate the genotoxicity and bioavailability of chromium(vi)-contaminated soils.a whole-cell bioreporter, acinetobacter baylyi adpwh_reca, was used to estimate the genotoxicity and bioavailability of chromium (vi) [cr(vi)] in contaminated soils. upon direct exposure to pre-sonicated soil samples, adpwh_reca gave the highest response to the genotoxicity of cr(vi) within 5 h with a detection limit of 2 µm cr(vi). investigations on sites contaminated with cr(vi) revealed that soil-associated cr(vi) was bioavailable to the bioreporter although it could not be extracted into the ...201525326171
mannitol-1-phosphate dehydrogenases/phosphatases: a family of novel bifunctional enzymes for bacterial adaptation to osmotic stress.the nutritionally versatile soil bacterium acinetobacter baylyi adp1 copes with salt stress by the accumulation of compatible solutes, a strategy that is widespread in nature. this bacterium synthesizes the sugar alcohol mannitol de novo in response to osmotic stress. in a previous study, we identified mtld, a mannitol-1-phosphate dehydrogenase, which is essential for mannitol biosynthesis and which catalyses the first step in mannitol biosynthesis, the reduction of fructose-6-phosphate (f-6-p) ...201524800891
toxicity assessment and modelling of moringa oleifera seeds in water purification by whole cell bioreporter.moringa oleifera has been used as a coagulation reagent for drinking water purification, especially in developing countries such as malawi. this research revealed the cytoxicity and genotoxicity of m. oleifera by acinetobacter bioreporter. the results indicated that significant cytoxicity effects were observed when the powdered m. oleifera seeds concentration is from 1 to 50 mg/l. through direct contact, ethanolic-water extraction and hexane extraction, the toxic effects of hydrophobic and hydro ...201424657325
bacterial whole-cell biosensors for the detection of contaminants in water and soils.bacterial whole-cell biosensors (bwbs) have unique advantages over conventional environmental monitoring techniques on the detection of toxicity and bioavailability of contaminants in water and soils. bwbs can also be rapid, sensitive, semiquantitative, cost-effective, and easy to use. in this study, a standard method is described for the detection of contaminants and toxicity in real water and soil samples using acinetobacter baylyi adp1-based biosensors.201424515368
production of triacylglycerols in escherichia coli by deletion of the diacylglycerol kinase gene and heterologous overexpression of atfa from acinetobacter baylyi adp1.this study investigated the production of triacylglycerols in cells of the wild type of escherichia coli and of a strain with a deleted diacylglycerol kinase gene (dgka). by overexpression of atfa from acinetobacter baylyi adp1 and fadd from e. coli in the dgka deletion mutant, cellular contents of up to 4.9% (w/w) triacylglycerols could be achieved in batch cultivation. furthermore, heterologous expression of atfa relieves the negative effects of dgka deletion on growth. process optimization an ...201424389701
a dna break inducer activates the anticodon nuclease rloc and the adaptive immunity in acinetobacter baylyi adp1.double-stranded dna breaks (dsb) cause bacteria to augment expression of dna repair and various stress response proteins. a puzzling exception educes the anticodon nuclease (acnase) rloc, which resembles the dsb responder rad50 and the antiviral, translation-disabling acnase prrc. while prrc's acnase is regulated by a dna restriction-modification (r-m) protein and a phage anti-dna restriction peptide, rloc has an internal acnase switch comprising a putative dsb sensor and coupled atpase. further ...201424062157
gene transfer potential of outer membrane vesicles of acinetobacter baylyi and effects of stress on vesiculation.outer membrane vesicles (omvs) are continually released from a range of bacterial species. numerous functions of omvs, including the facilitation of horizontal gene transfer (hgt) processes, have been proposed. in this study, we investigated whether omvs contribute to the transfer of plasmids between bacterial cells and species using gram-negative acinetobacter baylyi as a model system. omvs were extracted from bacterial cultures and tested for the ability to vector gene transfer into population ...201424657872
extracellular polymeric substance architecture influences natural genetic transformation of acinetobacter baylyi in biofilms.genetic exchange by natural transformation is an important mechanism of horizontal gene transfer in biofilms. thirty-two biofilm metrics were quantified in a heavily encapsulated acinetobacter baylyi strain and a miniencapsulated mutant strain, accounting for cellular architecture, extracellular polymeric substances (eps) architecture, and their combined biofilm architecture. in general, transformation location, abundance, and frequency were more closely correlated to eps architecture than to ce ...201425304505
a whole-cell bioreporter approach for the genotoxicity assessment of bioavailability of toxic compounds in contaminated soil in china.a whole-cell bacterial bioreporter acinetobacter baylyi strain adp1_reca_lux that responds to genotoxins was employed to directly assess the adverse effects of the bioavailable fraction of mitomycin c (mmc), benzo[a]pyrene (bap), chromium (vi) and lead (ii) in amended soils and soil samples from two fragile areas in china without soil pre-treatment. the amended soils containing pollutants with the concentrations as low as 0.4 mg/kg mmc, 0.5 mg/kg bap, 520 mg/kg cr (vi) and 2072 mg/kg pb (ii) wer ...201425243386
a mechanistic study on smob-adp1: an nadh:flavin oxidoreductase of the two-component styrene monooxygenase of acinetobacter baylyi adp1.two styrene monooxygenase types, stya/styb and stya1/stya2b, have been described each consisting of an epoxidase and a reductase. a gene fusion which led to the chimeric reductase stya2b and the occurrence in different phyla are major differences. identification of smoa/smob-adp1 of acinetobacter baylyi adp1 may enlighten the gene fusion event since phylogenetic analysis indicated both proteins to be more related to stya2b than to stya/styb. smob-adp1 is classified like styb and stya2b as hpac-l ...201425116410
less is more: selective advantages can explain the prevalent loss of biosynthetic genes in bacteria.bacteria that have adapted to nutrient-rich, stable environments are typically characterized by reduced genomes. the loss of biosynthetic genes frequently renders these lineages auxotroph, hinging their survival on an environmental uptake of certain metabolites. the evolutionary forces that drive this genome degradation, however, remain elusive. our analysis of 949 metabolic networks revealed auxotrophies are likely highly prevalent in both symbiotic and free-living bacteria. to unravel whether ...201424910088
rewiring the wax ester production pathway of acinetobacter baylyi adp1.wax esters are industrially relevant high-value molecules. for sustainable production of wax esters, bacterial cell factories are suggested to replace the chemical processes exploiting expensive starting materials. however, it is well recognized that new sophisticated solutions employing synthetic biology toolbox are required to improve and tune the cellular production platform to meet the product requirements. for example, saturated wax esters with alkanol chain lengths c12 or c14 that are conv ...201424898054
rationally engineered synthetic coculture for improved biomass and product formation.in microbial ecosystems, bacteria are dependent on dynamic interspecific interactions related to carbon and energy flow. substrates and end-metabolites are rapidly converted to other compounds, which protects the community from high concentrations of inhibitory molecules. in biotechnological applications, pure cultures are preferred because of the more straight-forward metabolic engineering and bioprocess control. however, the accumulation of unwanted side products can limit the cell growth and ...201425470793
identification of an osmo-dependent and an osmo-independent choline transporter in acinetobacter baylyi: implications in osmostress protection and metabolic adaptation.members of the genus acinetobacter are well known for their metabolic versatility that allows them to adapt to different ecological niches. in previous studies, we have demonstrated that acinetobacter baylyi adp1 can cope with high salinities by uptake and accumulation of the well-known compatible solute glycine betaine. here, we demonstrate that addition of choline restores growth at high salinities. we further show that choline was actively taken up by the cells and converted to glycine betain ...201423889709
metabolic engineering of acinetobacter baylyi adp1 for improved growth on gluconate and glucose.a high growth rate in bacterial cultures is usually achieved by optimizing growth conditions, but metabolism of the bacterium limits the maximal growth rate attainable on the carbon source used. this limitation can be circumvented by engineering the metabolism of the bacterium. acinetobacter baylyi has become a model organism for studies of bacterial metabolism and metabolic engineering due to its wide substrate spectrum and easy-to-engineer genome. it produces naturally storage lipids, such as ...201425192990
novel metabolic features in acinetobacter baylyi adp1 revealed by a multiomics approach.expansive knowledge of bacterial metabolism has been gained from genome sequencing output, but the high proportion of genes lacking a proper functional annotation in a given genome still impedes the accurate prediction of the metabolism of a cell. to access to a more global view of the functioning of the soil bacterium acinetobacter baylyi adp1, we adopted a multi 'omics' approach. application of rna-seq transcriptomics and lc/ms-based metabolomics, along with the systematic phenotyping of the c ...201425374488
prophage induction and differential reca and umudab transcriptome regulation in the dna damage responses of acinetobacter baumannii and acinetobacter baylyi.the sos response to dna damage that induces up to 10% of the prokaryotic genome requires reca action to relieve lexa transcriptional repression. in acinetobacter species, which lack lexa, the error-prone polymerase accessory umudab is instead required for ddrr induction after dna damage, suggesting it might be a lexa analog. rna-seq experiments defined the dna damage transcriptome (mitomycin c-induced) of wild type, reca and umudab mutant strains of both a. baylyi adp1 and a. baumannii atcc 1797 ...201424709747
bacterial natural transformation by highly fragmented and damaged dna.dna molecules are continuously released through decomposition of organic matter and are ubiquitous in most environments. such dna becomes fragmented and damaged (often <100 bp) and may persist in the environment for more than half a million years. fragmented dna is recognized as nutrient source for microbes, but not as potential substrate for bacterial evolution. here, we show that fragmented dna molecules (≥ 20 bp) that additionally may contain abasic sites, cross-links, or miscoding lesions ar ...201324248361
costly class-1 integrons and the domestication of the the functional integrase.class-1 integrons play an important role in the emergence and spread of antimicrobial resistance determinants. in a recent study we showed that host fitness was dramatically reduced following acquisition of these elements. these fitness costs were due to the presence of an active integrase and we suggested that the mechanistic explanation was due to reduced genetic stability through inti1 mediated recombination events between atti/attc and non-canonical sites in the chromosome. here we demonstra ...201323914313
tit-for-tat: type vi secretion system counterattack during bacterial cell-cell interactions.the bacterial type vi secretion system (t6ss) is a dynamic organelle that bacteria use to target prey cells for inhibition via translocation of effector proteins. time-lapse fluorescence microscopy has documented striking dynamics of opposed t6ss organelles in adjacent sister cells of pseudomonas aeruginosa. such cell-cell interactions have been termed "t6ss dueling" and likely reflect a biological process that is driven by t6ss antibacterial attack. here, we show that t6ss dueling behavior stro ...201323415234
transcriptomic and biochemical analyses identify a family of chlorhexidine efflux proteins.chlorhexidine is widely used as an antiseptic or disinfectant in both hospital and community settings. a number of bacterial species display resistance to this membrane-active biocide. we examined the transcriptomic response of a representative nosocomial human pathogen, acinetobacter baumannii, to chlorhexidine to identify the primary chlorhexidine resistance elements. the most highly up-regulated genes encoded components of a major multidrug efflux system, adeab. the next most highly overexpre ...201324277845
single-step selection of drug resistant acinetobacter baylyi adp1 mutants reveals a functional redundancy in the recruitment of multidrug efflux systems.members of the genus acinetobacter have been the focus recent attention due to both their clinical significance and application to molecular biology. the soil commensal bacterium acinetobacter baylyi adp1 has been proposed as a model system for molecular and genetic studies, whereas in a clinical environment, acinetobacter spp. are of increasing importance due to their propensity to cause serious and intractable systemic infections. clinically, a major factor in the success of acinetobacter spp. ...201323409126
staring at the cold sun: blue light regulation is distributed within the genus acinetobacter.we previously showed that the opportunistic nosocomial pathogen acinetobacter baumannii is able to sense and respond to light via blsa, a bluf (blue-light-sensing using fad)-domain photoreceptor protein. here, we extend our previous studies showing that light regulation is not restricted to a. baumannii, but rather widespread within the genus acinetobacter. first, we found that blue light modulates motility and biofilm formation in many species of the genus, including members of the acinetobacte ...201323358859
structure and biosynthesis of fimsbactins a-f, siderophores from acinetobacter baumannii and acinetobacter baylyi.novel chatechol/hydroxamate siderophores (named "fimsbactins") were identified in acinetobacter baumannii atcc 17978 and acinetobacter baylyi adp1. the major compound, fimsbactin a, was isolated from low-iron cultures of a. baylyi adp1, and its chemical structure was elucidated by mass spectrometry, and detailed (1)h, (13)c and (15)n nmr spectroscopy. from inverse feeding experiments following hplc-ms analysis, the structures of five additional derivatives were elucidated. the gene cluster encod ...201323456955
direct grafting of anti-fouling polyglycerol layers to steel and other technically relevant materials.direct grafting of hyperbranched polyglycerol (pg) layers onto the oxide surfaces of steel, aluminum, and silicon has been achieved through surface-initiated polymerization of 2-hydroxymethyloxirane (glycidol). optimization of the deposition conditions led to a protocol that employed n-methyl-2-pyrrolidone (nmp) as the solvent and temperatures of 100 and 140 °c, depending on the substrate material. in all cases, a linear growth of the pg layers could be attained, which allows for control of film ...201323856542
blue-light-dependent inhibition of twitching motility in acinetobacter baylyi adp1: additive involvement of three bluf-domain-containing proteins.twitching motility in acinetobacter baylyi adp1 is inhibited by moderate intensities of blue light in a temperature-dependent manner (maximally at 20 °c). we analysed the involvement of four predicted blue-light sensing using flavin (bluf)-domain-containing proteins encoded in the genome of this strain in the twitching motility phenotype. all four genes were expressed both in light and in darkness. a phylogenetic tree showed that one bluf domain, aciad2110, grouped separately from the other thre ...201323813679
synthesis of medium chain length fatty acid ethyl esters in engineered escherichia coli using endogenously produced medium chain fatty acids.microbial biosynthesis of fatty acid-derived biofuels from renewable carbon sources has attracted significant attention in recent years. free fatty acids (ffas) can be used as precursors for the production of micro-diesel. the expression of codon optimized two plants (umbellularia californica and cinnamomum camphora) medium-chain acyl-acyl carrier protein (acp) thioesterase genes (ucfatb and ccfatb) in escherichia coli resulted in a very high level of extractable medium-chain-specific hydrolytic ...201323769314
resolving the mechanism of bacterial inhibition by plant secondary metabolites employing a combination of whole-cell biosensors.tightening regulations regarding the use of biocides have stimulated interest in investigating alternatives to current antimicrobial strategies. plant essential oils and their constituent compounds are promising candidates as novel antimicrobial agents because of their excellent ability in killing microbes while being non-toxic to humans at antimicrobially-active concentrations. allyl isothiocyanate (ait), carvacrol, cinnamaldehyde (cnad), citral, and thymol were investigated for their antibacte ...201323566822
mannitol, a compatible solute synthesized by acinetobacter baylyi in a two-step pathway including a salt-induced and salt-dependent mannitol-1-phosphate dehydrogenase.the nutritionally versatile and naturally competent soil bacterium acinetobacter baylyi copes with salt stress by the accumulation of compatible solutes. nmr analyses revealed that cells amassed glutamate and the rather unusual sugar alcohol mannitol upon an increase of the external nacl concentration. to unravel the path of mannitol biosynthesis, the genome was inspected for genes potentially involved in its biosynthesis. a gene encoding a potential mannitol-1-phosphate dehydrogenase (mtld) was ...201323414076
whole cell bioreporter application for rapid detection and evaluation of crude oil spill in seawater caused by dalian oil tank explosion.accidents involving the release of crude oil to seawater pose serious threat to human and animal health, fisheries and marine ecosystems. a whole cell bioreporter detection method, which has unique advantages for the rapid evaluation on toxicity and bioavailability, is a useful tool to provide environmental risk assessments at crude oil-contaminated sites. acinetobacter baylyi adpwh_alk and adpwh_reca are chromosomally-based alkane and genotoxicity bioreporters which can be activated to express ...201323269319
identification of a residue affecting fatty alcohol selectivity in wax ester synthase.the terminal enzyme in the bacterial wax ester biosynthetic pathway is the bifunctional wax ester synthase/acyl-coenzyme a:diacylglycerol acyltransferase (ws/dgat), which utilizes a fatty alcohol and a fatty acyl-coenzyme a (coa) to synthesize the corresponding wax ester. in this report, we identify a specific residue in ws/dgat enzymes obtained from marinobacter aquaeolei vt8 and acinetobacter baylyi that alters fatty alcohol selectivity and kinetic parameters when modified to alternative resid ...201323087036
paar-repeat proteins sharpen and diversify the type vi secretion system spike.the bacterial type vi secretion system (t6ss) is a large multicomponent, dynamic macromolecular machine that has an important role in the ecology of many gram-negative bacteria. t6ss is responsible for translocation of a wide range of toxic effector molecules, allowing predatory cells to kill both prokaryotic as well as eukaryotic prey cells. the t6ss organelle is functionally analogous to contractile tails of bacteriophages and is thought to attack cells by initially penetrating them with a tri ...201323925114
acinetobacter baylyi long-term stationary-phase protein stip is a protease required for normal cell morphology and resistance to tellurite.we investigated the acinetobacter baylyi gene aciad1960, known from previous work to be expressed during long-term stationary phase. the protein encoded by this gene had been annotated as a conserved hypothetical protein, surrounded by putative tellurite resistance ("ter") proteins. sequence analysis suggested that the protein belongs to the duf1796 putative papain-like protease family. here, we show that the purified protein, subsequently named stip, has cysteine protease activity. deletion of ...201324206355
plasmid-mediated fitness advantage of acinetobacter baylyi in sulfadiazine-polluted soil.lowgc-type plasmids conferring resistance to sulfonamides have been frequently isolated from manure and manured soil. however, knowledge on the dynamics of plasmid-carrying populations in soil and their response to the presence of sulfonamides is scarce. here, we investigated effects of the sulfonamide resistance conferring plasmid phhv216 on the fitness of acinetobacter baylyi bd413 in soil after application of manure with or without the sulfonamide antibiotic sulfadiazine (sdz). the persistenc ...201324118075
boosting the free fatty acid synthesis of escherichia coli by expression of a cytosolic acinetobacter baylyi thioesterase. 201223057831
functional roles of tryptophan residues in diketoreductase from acinetobacter baylyi.diketoreductase (dkr) from acinetobacter baylyi contains two tryptophan residues at positions 149 and 222. trp-149 and trp-222 are located along the entry path of substrate into active site and at the dimer interface of dkr, respectively. single and double substitutions of these positions were generated to probe the roles of tryptophan residues. after replacing trp with ala and phe, biochemical and biophysical characteristics of the mutants were thoroughly investigated. enzyme activity and subst ...201222917029
analysis of is1236-mediated gene amplification events in acinetobacter baylyi adp1.recombination between insertion sequence copies can cause genetic deletion, inversion, or duplication. however, it is difficult to assess the fraction of all genomic rearrangements that involve insertion sequences. in previous gene duplication and amplification studies of acinetobacter baylyi adp1, an insertion sequence was evident in approximately 2% of the characterized duplication sites. gene amplification occurs frequently in all organisms and has a significant impact on evolution, adaptatio ...201222707704
the acinetobacter regulatory umudab protein cleaves in response to dna damage with chimeric lexa/umud characteristics.in the dna damage response of most bacteria, umud forms part of the error-prone (umud'(2) )c polymerase v and is activated for this function by self-cleavage after dna damage. however, the umud homolog (umudab) present throughout the acinetobacter genus encodes an extra n-terminal region, and in acinetobacter baylyi, regulates transcription of dna damage-induced genes. umudab expressed in cells was correspondingly larger (24 kda) than the escherichia coli umud (15 kda). dna damage from mitomycin ...201222697494
differences in substrate specificities of five bacterial wax ester synthases.wax esters are produced in certain bacteria as a potential carbon and energy storage compound. the final enzyme in the biosynthetic pathway responsible for wax ester production is the bifunctional wax ester synthase/acyl-coenzyme a (acyl-coa):diacylglycerol acyltransferase (ws/dgat), which utilizes a range of fatty alcohols and fatty acyl-coas to synthesize the corresponding wax ester. we report here the isolation and substrate range characterization for five ws/dgat enzymes from four different ...201222685145
epidemiological characteristics and genetic structure of blandm-1 in non-baumannii acinetobacter spp. in china.the goal of this study was to investigate the epidemiological characteristics and the surrounding genetic structure of bla(ndm-1) in non-baumannii acinetobacter spp. in china.201222604448
functional expression and characterization of five wax ester synthases in saccharomyces cerevisiae and their utility for biodiesel production.wax ester synthases (wss) can synthesize wax esters from alcohols and fatty acyl coenzyme a thioesters. the knowledge of the preferred substrates for each ws allows the use of yeast cells for the production of wax esters that are high-value materials and can be used in a variety of industrial applications. the products of wss include fatty acid ethyl esters, which can be directly used as biodiesel.201222364438
monitoring alkane degradation by single biobrick integration to an optimal cellular framework.synthetic biology enables rewiring and reconstruction of desirable biochemical routes using well-characterized biobricks. one goal is to optimize these biological systems in terms of robustness, functionality, and simplicity. thus, in addition to optimizing the molecular level of the metabolic network, choosing an optimal "chassis" can have a great significance in the constructed system. as an example, this study presents a simplified system for monitoring and studying long-chain n-alkane degrad ...201223651046
genome-wide selection for increased copy number in acinetobacter baylyi adp1: locus and context-dependent variation in gene amplification.renewed interest in gene amplification stems from its importance in evolution and a variety of medical problems ranging from drug resistance to cancer. however, amplified dna segments (amplicons) are not fully characterized in any organism. here we report a novel acinetobacter baylyi system for genome-wide studies. amplification mutants that consume aromatic compounds were selected under conditions requiring high-level expression from three promoters in a linked set of chromosomal genes. tools w ...201222211470
natural transformation facilitates transfer of transposons, integrons and gene cassettes between bacterial species.we have investigated to what extent natural transformation acting on free dna substrates can facilitate transfer of mobile elements including transposons, integrons and/or gene cassettes between bacterial species. naturally transformable cells of acinetobacter baylyi were exposed to dna from integron-carrying strains of the genera acinetobacter, citrobacter, enterobacter, escherichia, pseudomonas, and salmonella to determine the nature and frequency of transfer. exposure to the various dna sourc ...201222876180
long-term diversity and genome adaptation of acinetobacter baylyi in a minimal-medium chemostat.laboratory-based evolution experiments on microorganisms that do not recombine frequently show two distinct phases: an initial rapid increase in fitness followed by a slower regime. to explore the population structure and the evolutionary tree in the later stages of adaptation, we evolved a very large population (~3 × 10(10)) of acinetobacter baylyi bacteria for approximately 2,800 generations from a single clone. the population was maintained in a chemostat at a high dilution rate. nitrate in l ...201223254395
purification and characterization of an nad+-dependent xylb-like aryl alcohol dehydrogenase identified in acinetobacter baylyi adp1.the gene xylb(adp1) from acinetobacter baylyi adp1 (gene annotation number aciad1578), coding for a putative aryl alcohol dehydrogenase, was heterologously expressed in escherichia coli bl21(de3). the respective aryl alcohol dehydrogenase was purified by fast protein liquid chromatography to apparent electrophoretic homogeneity. the predicted molecular weight of 39,500 per subunit was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. according to the native m(w) as determin ...201223042182
Synthesis of FAEEs from glycerol in engineered Saccharomyces cerevisiae using endogenously produced ethanol by heterologous expression of an unspecific bacterial acyltransferase.The high price of petroleum-based diesel fuel has led to the development of alternative fuels, such as ethanol. Saccharomyces cerevisiae was metabolically engineered to utilize glycerol as a substrate for ethanol production. For the synthesis of fatty acid ethyl esters (FAEEs) by engineered S. cerevisiae that utilize glycerol as substrate, heterologous expression of an unspecific acyltransferase from Acinetobacter baylyi with glycerol utilizing genes was established. As a result, the engineered ...201221858787
Expression Vectors for Acinetobacter baylyi ADP1.Acinetobacter baylyi ADP1 is naturally competent and proficient at homologous recombination, so it can be transformed without restriction digests or ligation reactions. Expression vectors for this system, however, are not yet widely available. Here we describe the construction and characterization of inducible expression vectors that replicate as plasmids in A. baylyi or integrate into a nonessential part of its chromosome. These tools will facilitate the engineering of genes and genomes in this ...201222020504
identification of acinetobacter species: is bruker biotyper maldi-tof mass spectrometry a good alternative to molecular techniques?acinetobacter spp. has become a leading cause of nosocomial infection in recent years. phenotypic similarities between the species in the genus have made it difficult to identify them clearly using routine diagnostic methods. consequently, more relevant species have been grouped together as acinetobacter calcoaceticus-acinetobacter baumannii complex (a. baumannii, a. calcoaceticus, acinetobacter genospecies 3 and a. genospecies 13tu). however, there are other species that may also have clinical ...201222266021
microbial urate catabolism: characterization of hpyo, a non-homologous isofunctional isoform of the flavoprotein urate hydroxylase hpxo.in aerobic cells, urate is oxidized to 5-hydroxyisourate by two distinct enzymes: a coenzyme-independent urate oxidase (ec 1.7.3.3) found in eukaryotes and bacteria like bacillus subtilis and a prokaryotic flavoprotein urate hydroxylase (hpxo) originally found in some klebsiella species. more cases of analogous or non-homologous isofunctional enzymes (nise) for urate catabolism have been hypothesized by inspecting bacterial genomes. here, we used a functional complementation approach in which a ...201223760935
characterization and modeling of transcriptional cross-regulation in acinetobacter baylyi adp1.synthetic biology involves reprogramming and engineering of regulatory genes in innovative ways for the implementation of novel tasks. transcriptional gene regulation systems induced by small molecules in prokaryotes provide a rich source for logic gates. cross-regulation, whereby a promoter is activated by different molecules or different promoters are activated by one molecule, can be used to design an or-gate and achieve cross-talk between gene networks in cells. acinetobacter baylyi adp1 is ...201223651250
a trade-off between the fitness cost of functional integrases and long-term stability of integrons.horizontal gene transfer (hgt) plays a major role in bacterial microevolution as evident from the rapid emergence and spread of antimicrobial drug resistance. few studies have however addressed the population dynamics of newly imported genetic elements after hgt. here, we show that newly acquired class-1 integrons from salmonella enterica serovar typhimurium and acinetobacter baumannii, free of associated transposable elements, strongly reduce host fitness in acinetobacter baylyi. insertional in ...201223209414
in vivo-validated essential genes identified in acinetobacter baumannii by using human ascites overlap poorly with essential genes detected on laboratory media.a critical feature of a potential antimicrobial target is the characteristic of being essential for growth and survival during host infection. for bacteria, genome-wide essentiality screens are usually performed on rich laboratory media. this study addressed whether genes detected in that manner were optimal for the identification of antimicrobial targets since the in vivo milieu is fundamentally different. mutant derivatives of a clinical isolate of acinetobacter baumannii were screened for gro ...201222911967
whole-cell bacterial bioreporter for actively searching and sensing of alkanes and oil spills.acinetobacter baylyi adp1 was found to tolerate seawater and have a special ability of adhering to an oil-water interface of 10-80 µm emulsified mineral and crude oil droplets. these properties make adp1 an ideal bacterial chassis for constructing bioreporters that are able to actively search and sense oil spill in water and soils. acinetobacter baylyi bioreporter adpwh_alk was developed and applied to the detection of alkanes and alkenes in water, seawater and soils. bioreporter adpwh_alk was a ...201221951420
Real-time monitoring of intracellular wax ester metabolism.Wax esters are industrially relevant molecules exploited in several applications of oleochemistry and food industry. At the moment, the production processes mostly rely on chemical synthesis from rather expensive starting materials, and therefore solutions are sought from biotechnology. Bacterial wax esters are attractive alternatives, and especially the wax ester metabolism of Acinetobacter sp. has been extensively studied. However, the lack of suitable tools for rapid and simple monitoring of ...201121961954
identification of important residues in diketoreductase from acinetobacter baylyi by molecular modeling and site-directed mutagenesis.diketoreductase (dkr) from acinetobacter baylyi exhibits a unique property of double reduction of a β, δ-diketo ester with excellent stereoselectivity, which can serve as an efficient biocatalyst for the preparation of an important chiral intermediate for cholesterol lowering statin drugs. taken the advantage of high homology between dkr and human heart 3-hydroxyacyl-coa dehydrogenase (had), a molecular model was created to compare the tertiary structures of dkr and had. in addition to the possi ...201121893158
bacterial recombination promotes the evolution of multi-drug-resistance in functionally diverse populations.bacterial recombination is believed to be a major factor explaining the prevalence of multi-drug-resistance (mdr) among pathogenic bacteria. despite extensive evidence for exchange of resistance genes from retrospective sequence analyses, experimental evidence for the evolutionary benefits of bacterial recombination is scarce. we compared the evolution of mdr between populations of acinetobacter baylyi in which we manipulated both the recombination rate and the initial diversity of strains with ...201122048956
diverse dna damage responses in acinetobacter include the capacity for dna damage-induced mutagenesis in the opportunistic pathogens acinetobacter baumannii and acinetobacter ursingii.error-prone and error-free dna damage repair responses that are induced in most bacteria after exposure to various chemicals, antibiotics, or radiation sources were surveyed across the acinetobacter genus. the error prone sos mutagenesis response occurs when dna damage induces a cell's umudc- or dinp-encoded error-prone polymerases. the model acinetobacter baylyi strain adp1 possesses an unusual, regulatory umud allele (umudab) with an extended 5' region, and only incomplete fragments of umuc. d ...201122117008
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