Publications

the structural biology of type iv secretion systems.	type iv secretion systems (t4sss) are versatile secretion systems that are found in both gram-negative and gram-positive bacteria and secrete a wide range of substrates, from single proteins to protein-protein and protein-dna complexes. they usually consist of 12 components that are organized into atp-powered, double-membrane-spanning complexes. the structures of single soluble components or domains have been solved, but an understanding of how these structures come together has only recently be ...	2009	19756009
gram-negative bacterial sensors for eukaryotic signal molecules.	ample evidence exists showing that eukaryotic signal molecules synthesized and released by the host can activate the virulence of opportunistic pathogens. the sensitivity of prokaryotes to host signal molecules requires the presence of bacterial sensors. these prokaryotic sensors, or receptors, have a double function: stereospecific recognition in a complex environment and transduction of the message in order to initiate bacterial physiological modifications. as messengers are generally unable t ...	2009	22399982
bacterial responses to photo-oxidative stress.	singlet oxygen is one of several reactive oxygen species that can destroy biomolecules, microorganisms and other cells. traditionally, the response to singlet oxygen has been termed photo-oxidative stress, as light-dependent processes in photosynthetic cells are major biological sources of singlet oxygen. recent work identifying a core set of singlet oxygen stress response genes across various bacterial species highlights the importance of this response for survival by both photosynthetic and no ...	2009	19881522
quorum sensing and social networking in the microbial world.	for many years, bacterial cells were considered primarily as selfish individuals, but, in recent years, it has become evident that, far from operating in isolation, they coordinate collective behaviour in response to environmental challenges using sophisticated intercellular communication networks. cell-to-cell communication between bacteria is mediated by small diffusible signal molecules that trigger changes in gene expression in response to fluctuations in population density. this process, ge ...	2009	19674996
optimal tuning of bacterial sensing potential.	through production and sensing of small signal molecules, quorum sensing (qs) enables bacteria to detect changes in their density and regulate their functions accordingly. qs systems are tremendously diverse in terms of their specific sensory components, the biochemical and transport properties of signaling molecules, their target functions and the context in which qs-mediated functions are activated. cutting across this diversity, however, the central architecture of qs systems is universal; it ...	2009	19584835
protein secretion systems in bacterial-host associations, and their description in the gene ontology.	protein secretion plays a central role in modulating the interactions of bacteria with their environments. this is particularly the case when symbiotic bacteria (whether pathogenic, commensal or mutualistic) are interacting with larger host organisms. in the case of gram-negative bacteria, secretion requires translocation across the outer as well as the inner membrane, and a diversity of molecular machines have been elaborated for this purpose. a number of secreted proteins are destined to enter ...	2009	19278550
amidoligases with atp-grasp, glutamine synthetase-like and acetyltransferase-like domains: synthesis of novel metabolites and peptide modifications of proteins.	recent studies have shown that the ubiquitin system had its origins in ancient cofactor/amino acid biosynthesis pathways. preliminary studies also indicated that conjugation systems for other peptide tags on proteins, such as pupylation, have evolutionary links to cofactor/amino acid biosynthesis pathways. following up on these observations, we systematically investigated the non-ribosomal amidoligases of the atp-grasp, glutamine synthetase-like and acetyltransferase folds by classifying the kno ...	2009	20023723
comprehensive comparative-genomic analysis of type 2 toxin-antitoxin systems and related mobile stress response systems in prokaryotes.	the prokaryotic toxin-antitoxin systems (tas, also referred to as ta loci) are widespread, mobile two-gene modules that can be viewed as selfish genetic elements because they evolved mechanisms to become addictive for replicons and cells in which they reside, but also possess "normal" cellular functions in various forms of stress response and management of prokaryotic population. several distinct tas of type 1, where the toxin is a protein and the antitoxin is an antisense rna, and numerous, unr ...	2009	19493340
a subset of the diverse cog0523 family of putative metal chaperones is linked to zinc homeostasis in all kingdoms of life.	cog0523 proteins are, like the nickel chaperones of the ureg family, part of the g3e family of gtpases linking them to metallocenter biosynthesis. even though the first cog0523-encoding gene, cobw, was identified almost 20 years ago, little is known concerning the function of other members belonging to this ubiquitous family.	2009	19822009
bacterial contamination of pediatric whole blood transfusions in a kenyan hospital.	hospitalized children in sub-saharan africa frequently receive whole blood transfusions for severe anemia. the risk from bacterial contamination of blood for transfusion in sub-saharan africa is not known. this study assessed the frequency of bacterial contamination of pediatric whole blood transfusions at a referral hospital in kenya.	2009	19682331
catalytic bioscavengers against toxic esters, an alternative approach for prophylaxis and treatments of poisonings.	bioscavengers are biopharmaceuticals that specifically react with toxicants. thus, enzymes reacting with poisonous esters can be used as bioscavengers for neutralization of toxic molecules before they reach physiological targets. parenteral administration of bioscavengers is, therefore, intended for prophylaxis or pre-treatments, emergency and post-exposure treatments of intoxications. these enzymes can also be used for application on skin, mucosa and wounds as active components of topical skin ...	2009	22649587
origin of an alternative genetic code in the extremely small and gc-rich genome of a bacterial symbiont.	the genetic code relates nucleotide sequence to amino acid sequence and is shared across all organisms, with the rare exceptions of lineages in which one or a few codons have acquired novel assignments. recoding of uga from stop to tryptophan has evolved independently in certain reduced bacterial genomes, including those of the mycoplasmas and some mitochondria. small genomes typically exhibit low guanine plus cytosine (gc) content, and this bias in base composition has been proposed to drive ug ...	2009	19609354
sculpting the bacterial cell.	prokaryotes come in a wide variety of shapes, determined largely by natural selection, physical constraints, and patterns of cell growth and division. because of their relative simplicity, bacterial cells are excellent models for how genes and proteins can directly determine morphology. recent advances in cytological methods for bacteria have shown that distinct cytoskeletal filaments composed of actin and tubulin homologs are important for guiding growth patterns of the cell wall in bacteria, a ...	2009	19906583
genomic basis for natural product biosynthetic diversity in the actinomycetes.		2009	19844637
conformational sampling, catalysis, and evolution of the bacterial phosphotriesterase.	to efficiently catalyze a chemical reaction, enzymes are required to maintain fast rates for formation of the michaelis complex, the chemical reaction and product release. these distinct demands could be satisfied via fluctuation between different conformational substates (css) with unique configurations and catalytic properties. however, there is debate as to how these rapid conformational changes, or dynamics, exactly affect catalysis. as a model system, we have studied bacterial phosphotriest ...	2009	19966226
transient expression of organophosphorus hydrolase to enhance the degrading activity of tomato fruit on coumaphos.	we constructed an expression cassette of the organophosphorus pesticide degrading (opd) gene under the control of the e8 promoter. then opd was transformed into tomato fruit using an agroinfiltration transient expression system. beta-glucuronidase (gus) staining, reverse transcription-polymerase chain reaction (rt-pcr), wavelength scanning, and fluorescent reaction were performed to examine the expression of the opd gene and the hydrolysis activity on coumaphos of organophosphorus hydrolase (oph ...	2009	19235273
investigation of atomic level patterns in protein--small ligand interactions.	shape complementarity and non-covalent interactions are believed to drive protein-ligand interaction. to date protein-protein, protein-dna, and protein-rna interactions were systematically investigated, which is in contrast to interactions with small ligands. we investigate the role of covalent and non-covalent bonds in protein-small ligand interactions using a comprehensive dataset of 2,320 complexes.	2009	19221587
metal a and metal b sites of nuclear rna polymerases pol iv and pol v are required for sirna-dependent dna methylation and gene silencing.	plants are unique among eukaryotes in having five multi-subunit nuclear rna polymerases: the ubiquitous rna polymerases i, ii and iii plus two plant-specific activities, nuclear rna polymerases iv and v (previously known as polymerases iva and ivb). pol iv and pol v are not required for viability but play non-redundant roles in small interfering rna (sirna)-mediated pathways, including a pathway that silences retrotransposons and endogenous repeats via sirna-directed dna methylation. rna polymer ...	2009	19119310
horizontal gene transfer and diverse functional constrains within a common replication-partitioning system in alphaproteobacteria: the repabc operon.	the repabc plasmid family, which is extensively present within alphaproteobacteria, and some secondary chromosomes of the rhizobiales have the particular feature that all the elements involved in replication and partitioning reside within one transcriptional unit, the repabc operon. given the functional interactions among the elements of the repabc operon, and the fact that they all reside in the same operon, a common evolutionary history would be expected if the entire operon had been horizonta ...	2009	19919719
evolution of efficient pathways for degradation of anthropogenic chemicals.	anthropogenic compounds used as pesticides, solvents and explosives often persist in the environment and can cause toxicity to humans and wildlife. the persistence of anthropogenic compounds is due to their recent introduction into the environment; microbes in soil and water have had relatively little time to evolve efficient mechanisms for degradation of these new compounds. some anthropogenic compounds are easily degraded, whereas others are degraded very slowly or only partially, leading to a ...	2009	19620997
genetic diversity of siderophore-producing bacteria of tobacco rhizosphere.	the genetic diversity of siderophore-producing bacteria of tobacco rhizosphere was studied by amplified ribosomal dna restriction analysis (ardra), 16s rrna sequence homology and phylogenetics analysis methods. studies demonstrated that 85% of the total 354 isolates produced siderophores in iron limited liquid medium. a total of 28 ardra patterns were identified among the 299 siderophore-producing bacterial isolates. the 28 ardra patterns represented bacteria of 14 different genera belonging to ...	2009	24031358
lifestyles of the effector rich: genome-enabled characterization of bacterial plant pathogens.		2009	19515788
underexplored niches in research on plant pathogenic bacteria.		2009	19561122
an arabidopsis flavonoid transporter is required for anther dehiscence and pollen development.	flower flavonoid transporter (fft) encodes a multidrug and toxin efflux family transporter in arabidopsis thaliana. fft (atdtx35) is highly transcribed in floral tissues, the transcript being localized to epidermal guard cells, including those of the anthers, stigma, siliques and nectaries. mutant analysis demonstrates that the absence of fft transcript affects flavonoid levels in the plant and that the altered flavonoid metabolism has wide-ranging consequences. root growth, seed development and ...	2009	19995827
functional analysis of alpha-dox2, an active alpha-dioxygenase critical for normal development in tomato plants.	plant alpha-dioxygenases initiate the synthesis of oxylipins by catalyzing the incorporation of molecular oxygen at the alpha-methylene carbon atom of fatty acids. previously, alpha-dox1 has been shown to display alpha-dioxygenase activity and to be implicated in plant defense. in this study, we investigated the function of a second alpha-dioxygenase isoform, alpha-dox2, in tomato (solanum lycopersicum) and arabidopsis (arabidopsis thaliana). recombinant slalpha-dox2 and atalpha-dox2 proteins ca ...	2009	19759339
control of the pattern-recognition receptor efr by an er protein complex in plant immunity.	in plant innate immunity, the surface-exposed leucine-rich repeat receptor kinases efr and fls2 mediate recognition of the bacterial pathogen-associated molecular patterns ef-tu and flagellin, respectively. we identified the arabidopsis stromal-derived factor-2 (sdf2) as being required for efr function, and to a lesser extent fls2 function. sdf2 resides in an endoplasmic reticulum (er) protein complex with the hsp40 erdj3b and the hsp70 bip, which are components of the er-quality control (er-qc) ...	2009	19763086
actin-depolymerizing factor2-mediated actin dynamics are essential for root-knot nematode infection of arabidopsis.	reorganization of the actin and microtubule networks is known to occur in targeted vascular parenchymal root cells upon infection with the nematode meloidogyne incognita. here, we show that actin-depolymerizing factor (adf) is upregulated in the giant feeding cells of arabidopsis thaliana that develop upon nematode infection and that knockdown of a specific adf isotype inhibits nematode proliferation. analysis of the levels of transcript and the localization of seven adf genes shows that five ar ...	2009	19794115
in planta expression screens of phytophthora infestans rxlr effectors reveal diverse phenotypes, including activation of the solanum bulbocastanum disease resistance protein rpi-blb2.	the irish potato famine pathogen phytophthora infestans is predicted to secrete hundreds of effector proteins. to address the challenge of assigning biological functions to computationally predicted effector genes, we combined allele mining with high-throughput in planta expression. we developed a library of 62 infection-ready p. infestans rxlr effector clones, obtained using primer pairs corresponding to 32 genes and assigned activities to several of these genes. this approach revealed that 16 ...	2009	19794118
gene regulation in parthenocarpic tomato fruit.	parthenocarpy is potentially a desirable trait for many commercially grown fruits if undesirable changes to structure, flavour, or nutrition can be avoided. parthenocarpic transgenic tomato plants (cv microtom) were obtained by the regulation of genes for auxin synthesis (iaam) or responsiveness (rolb) driven by defh9 or the inner no outer (ino) promoter from arabidopsis thaliana. fruits at a breaker stage were analysed at a transcriptomic and metabolomic level using microarrays, real-time rever ...	2009	19700496
are small gtpases signal hubs in sugar-mediated induction of fructan biosynthesis?	external sugar initiates biosynthesis of the reserve carbohydrate fructan, but the molecular processes mediating this response remain obscure. previously it was shown that a phosphatase and a general kinase inhibitor hamper fructan accumulation. we use various phosphorylation inhibitors both in barley and in arabidopsis and show that the expression of fructan biosynthetic genes is dependent on pp2a and different kinases such as tyr-kinases and pi3-kinases. to further characterize the phosphoryla ...	2009	19672308
the fractionated orthology of bs2 and rx/gpa2 supports shared synteny of disease resistance in the solanaceae.	comparative genomics provides a powerful tool for the identification of genes that encode traits shared between crop plants and model organisms. pathogen resistance conferred by plant r genes of the nucleotide-binding-leucine-rich-repeat (nb-lrr) class is one such trait with great agricultural importance that occupies a critical position in understanding fundamental processes of pathogen detection and coevolution. the proposed rapid rearrangement of r genes in genome evolution would make compara ...	2009	19474202
recent advances in pamp-triggered immunity against bacteria: pattern recognition receptors watch over and raise the alarm.		2009	19561123
evidence for a role of gibberellins in salicylic acid-modulated early plant responses to abiotic stress in arabidopsis seeds.	exogenous application of gibberellic acid (ga(3)) was able to reverse the inhibitory effect of salt, oxidative, and heat stresses in the germination and seedling establishment of arabidopsis (arabidopsis thaliana), this effect being accompanied by an increase in salicylic acid (sa) levels, a hormone that in recent years has been implicated in plant responses to abiotic stress. furthermore, this treatment induced an increase in the expression levels of the isochorismate synthase1 and nonexpressor ...	2009	19439570
arabidopsis chloroplastic glutathione peroxidases play a role in cross talk between photooxidative stress and immune responses.	glutathione peroxidases (gpxs; ec 1.11.1.9) are key enzymes of the antioxidant network in plants and animals. in order to investigate the role of antioxidant systems in plant chloroplasts, we generated arabidopsis (arabidopsis thaliana) transgenic lines that are depleted specifically in chloroplastic (cp) forms of gpx1 and gpx7. we show that reduced cpgpx expression, either in transgenic lines with lower total cpgpx expression (gpx1 and gpx7) or in a gpx7 insertion mutant, leads to compromised p ...	2009	19363092
comparison of the transcriptomes of american chestnut (castanea dentata) and chinese chestnut (castanea mollissima) in response to the chestnut blight infection.	background1471-2229-9-51: american chestnut (castanea dentata) was devastated by an exotic pathogen in the beginning of the twentieth century. this chestnut blight is caused by cryphonectria parasitica, a fungus that infects stem tissues and kills the trees by girdling them. because of the great economic and ecological value of this species, significant efforts have been made over the century to combat this disease, but it wasn't until recently that a focused genomics approach was initiated. pri ...	2009	19426529
genetic dissection of verticillium wilt resistance mediated by tomato ve1.	vascular wilt diseases caused by soil-borne pathogens are among the most devastating plant diseases worldwide. the verticillium genus includes vascular wilt pathogens with a wide host range. although v. longisporum infects various hosts belonging to the cruciferaceae, v. dahliae and v. albo-atrum cause vascular wilt diseases in over 200 dicotyledonous species, including economically important crops. a locus responsible for resistance against race 1 strains of v. dahliae and v. albo-atrum has bee ...	2009	19321708
a novel pathogenicity gene is required in the rice blast fungus to suppress the basal defenses of the host.	for successful colonization and further reproduction in host plants, pathogens need to overcome the innate defenses of the plant. we demonstrate that a novel pathogenicity gene, des1, in magnaporthe oryzae regulates counter-defenses against host basal resistance. the des1 gene was identified by screening for pathogenicity-defective mutants in a t-dna insertional mutant library. bioinformatic analysis revealed that this gene encodes a serine-rich protein that has unknown biochemical properties, a ...	2009	19390617
over-expression of a tomato n-acetyl-l-glutamate synthase gene (slnags1) in arabidopsis thaliana results in high ornithine levels and increased tolerance in salt and drought stresses.	a single copy of the n-acetyl-l-glutamate synthase gene (slnags1) has been isolated from tomato. the deduced amino acid sequence consists of 604 amino acids and shows a high level of similarity to the predicted arabidopsis nags1 and nags2 proteins. furthermore, the n-terminus argb domain and the c-terminus arga domain found in slnags1 are similar to the structural arrangements that have been reported for other predicted nags proteins. slnags1 was expressed at high levels in all aerial organs, an ...	2009	19357433
rice pi5-mediated resistance to magnaporthe oryzae requires the presence of two coiled-coil-nucleotide-binding-leucine-rich repeat genes.	rice blast, caused by the fungus magnaporthe oryzae, is one of the most devastating diseases of rice. to understand the molecular basis of pi5-mediated resistance to m. oryzae, we cloned the resistance (r) gene at this locus using a map-based cloning strategy. genetic and phenotypic analyses of 2014 f2 progeny from a mapping population derived from a cross between ir50, a susceptible rice cultivar, and the ril260 line carrying pi5 enabled us to narrow down the pi5 locus to a 130-kb interval. seq ...	2009	19153255
mitogen-activated protein kinases 3 and 6 are required for full priming of stress responses in arabidopsis thaliana.	in plants and animals, induced resistance (ir) to biotic and abiotic stress is associated with priming of cells for faster and stronger activation of defense responses. it has been hypothesized that cell priming involves accumulation of latent signaling components that are not used until challenge exposure to stress. however, the identity of such signaling components has remained elusive. here, we show that during development of chemically induced resistance in arabidopsis thaliana, priming is a ...	2009	19318610
common and contrasting themes in host cell-targeted effectors from bacterial, fungal, oomycete and nematode plant symbionts described using the gene ontology.	a wide diversity of plant-associated symbionts, including microbes, produce proteins that can enter host cells, or are injected into host cells in order to modify the physiology of the host to promote colonization. these molecules, termed effectors, commonly target the host defense signaling pathways in order to suppress the defense response. others target the gene expression machinery or trigger specific modifications to host morphology or physiology that promote the nutrition and proliferation ...	2009	19278551
apoplastic effectors secreted by two unrelated eukaryotic plant pathogens target the tomato defense protease rcr3.	current models of plant-pathogen interactions stipulate that pathogens secrete effector proteins that disable plant defense components known as virulence targets. occasionally, the perturbations caused by these effectors trigger innate immunity via plant disease resistance proteins as described by the "guard hypothesis." this model is nicely illustrated by the interaction between the fungal plant pathogen cladosporium fulvum and tomato. c. fulvum secretes a protease inhibitor avr2 that targets t ...	2009	19171904
mining the arabidopsis and rice genomes for cyclophilin protein families.	cyclophilins, which possess peptidyl-prolyl isomerase activity, are cellular targets of immunosuppressant drugs and involved in a wide variety of functions. while the arabidopsis thaliana genome contains the largest number of cyclophilins, the number of plant cyclophilins available in databases is small compared to that of other organisms. it implies that many cyclophilins are yet to be identified in plants. in order to identify cyclophilin candidates from available plant sequence data, we exami ...	2009	19525202
a critical role for the tify motif in repression of jasmonate signaling by a stabilized splice variant of the jasmonate zim-domain protein jaz10 in arabidopsis.	jasmonate zim-domain (jaz) proteins act as repressors of jasmonate (ja) signaling. perception of bioactive jas by the f-box protein coronatine insensitive1 (coi1) causes degradation of jazs via the ubiquitin-proteasome pathway, which in turn activates the expression of genes involved in plant growth, development, and defense. jaz proteins contain two highly conserved sequence regions: the jas domain that interacts with coi1 to destabilize the repressor and the zim domain of unknown function. her ...	2009	19151223
silencing of vlaro2 for chorismate synthase revealed that the phytopathogen verticillium longisporum induces the cross-pathway control in the xylem.	the first leaky auxotrophic mutant for aromatic amino acids of the near-diploid fungal plant pathogen verticillium longisporum (vl) has been generated. vl enters its host brassica napus through the roots and colonizes the xylem vessels. the xylem contains little nutrients including low concentrations of amino acids. we isolated the gene vlaro2 encoding chorismate synthase by complementation of the corresponding yeast mutant strain. chorismate synthase produces the first branch point intermediate ...	2010	19826808
differential effects of human and plant n-acetylglucosaminyltransferase i (gnti) in plants.	in plants and animals, the first step in complex type n-glycan formation on glycoproteins is catalyzed by n-acetylglucosaminyltransferase i (gnti). we show that the cgl1-1 mutant of arabidopsis, which lacks gnti activity, is fully complemented by yfp-labeled plant atgnti, but only partially complemented by yfp-labeled human hugnti and that this is due to post-transcriptional events. in contrast to atgnti-yfp, only low levels of hugnti-yfp protein was detected in transgenic plants. in protoplast ...	2010	19826906
detection of quorum sensing signal molecules and mutation of luxs gene in vibrio ichthyoenteri.	some pathogenic species belonging to the vibrionaceae family have been shown to regulate virulence through a complicated network of quorum sensing systems. in this study, three kinds of n-acylhomoserine lactone (ahl) signal molecules were detected in vibrio ichthyoenteri da3, a pathogen of cultured turbot (scophthalmus maximus), with the agrobacterium tumefaciens reporter strain kyc55 (pjz372)(pjz384)(pjz410). da3 produced ahls during the entire growth phase, and the level of ahls increased, acc ...	2010	19878720
transient assays for the analysis of mirna processing and function.	transient assays provide a convenient alternative to stable transformation. for small rna analysis in plants, the most widely used method, commonly named agroinfiltration, makes use of agrobacterium tumefaciens to deliver transgenes into leaf cells of nicotiana benthamiana. compared to the generation of stably transformed plants, agroinfiltration is more rapid, and samples can be analyzed a few days after inoculation. agroinfiltration has been used successfully in many different applications, in ...	2010	19802601
three cotton genes preferentially expressed in flower tissues encode actin-depolymerizing factors which are involved in f-actin dynamics in cells.	to investigate whether the high expression levels of actin-depolymerizing factor genes are related to pollen development, three ghadf genes (cdnas) were isolated and characterized in cotton. among them, ghadf6 and ghadf8 were preferentially expressed in petals, whereas ghadf7 displayed the highest level of expression in anthers, revealing its anther specificity. the ghadf7 transcripts in anthers reached its peak value at flowering, suggesting that its expression is developmentally-regulated in a ...	2010	19861654
an intracellular ph gradient in the anammox bacterium kuenenia stuttgartiensis as evaluated by 31p nmr.	the cytoplasm of anaerobic ammonium oxidizing (anammox) bacteria consists of three compartments separated by membranes. it has been suggested that a proton motive force may be generated over the membrane of the innermost compartment, the "anammoxosome". 31p nuclear magnetic resonance (nmr) spectroscopy was employed to investigate intracellular ph differences in the anammox bacterium kuenenia stuttgartiensis. with in vivo nmr, spectra were recorded of active, highly concentrated suspensions of k. ...	2010	19862513
the pseudomonas syringae type iii effector hopg1 targets mitochondria, alters plant development and suppresses plant innate immunity.	the bacterial plant pathogen pseudomonas syringae uses a type iii protein secretion system to inject type iii effectors into plant cells. primary targets of these effectors appear to be effector-triggered immunity (eti) and pathogen-associated molecular pattern (pamp)-triggered immunity (pti). the type iii effector hopg1 is a suppressor of eti that is broadly conserved in bacterial plant pathogens. here we show that hopg1 from p. syringae pv. tomato dc3000 also suppresses pti. interestingly, hop ...	2010	19863557
pyr/pyl/rcar family members are major in-vivo abi1 protein phosphatase 2c-interacting proteins in arabidopsis.	abscisic acid (aba) mediates resistance to abiotic stress and controls developmental processes in plants. the group-a pp2cs, of which abi1 is the prototypical member, are protein phosphatases that play critical roles as negative regulators very early in aba signal transduction. because redundancy is thought to limit the genetic dissection of early aba signalling, to identify redundant and early aba signalling proteins, we pursued a proteomics approach. we generated yfp-tagged abi1 arabidopsis ex ...	2010	19874541
transformation of the flax rust fungus, melampsora lini: selection via silencing of an avirulence gene.	rust fungi cause devastating diseases on many important food crops, with a damaging stem rust epidemic currently affecting wheat production in africa and the middle east. these parasitic fungi propagate exclusively on plants, precluding the use of many biotechnological tools available for other culturable fungi. in particular the lack of a stable transformation system has been an impediment to the genetic manipulation required for molecular analysis of rust pathogenicity. we have developed an ag ...	2010	19874543
establishment of a system based on universal multiplex-pcr for screening genetically modified crops.	the rapid development of many genetically modified (gm) crops in the past two decades makes it necessary to introduce an alternative strategy for routine screening and identification. in this study, we established a universal multiplex pcr detection system which will effectively reduce the number of reactions needed for sample identification. the pcr targets of this system include the six most frequently used transgenic elements: cauliflower mosaic virus (camv) 35s promoter, agrobacterium tumefa ...	2010	19855961
the use of 35s and tnos expression elements in the measurement of genetically engineered plant materials.	an online survey was conducted by the international life sciences institute, food biotechnology committee, on the use of qualitative and quantitative polymerase chain reaction (pcr) assays for cauliflower mosaic virus 35s promoter and agrobacterium tumefaciens tnos dna sequence elements for the detection of genetically engineered (ge) crop plant material. forty-four testing laboratories around the world completed the survey. the results showed the widespread use of such methods, the multiplicity ...	2010	19856176
mutational analysis of the active site residues of a d: -psicose 3-epimerase from agrobacterium tumefaciens.	d-psicose 3-epimerase from agrobacterium tumefacience catalyzes the conversion of d: -fructose to d-psicose. according to mutational analysis, the ring at position 112, the negative charge at position 156, and the positive charge at position 215 were essential components for enzyme activity and for binding fructose and psicose. the surface contact area and distance to the bound substrate by molecular modeling suggest that the positive charge of arg215 was involved in stabilization of cis-endiol ...	2010	19859667
pantothenate kinase from the thermoacidophilic archaeon picrophilus torridus.	pantothenate kinase (coaa) catalyzes the first step of the coenzyme a (coa) biosynthetic pathway and controls the intracellular concentrations of coa through feedback inhibition in bacteria. an alternative enzyme found in archaea, pantoate kinase, is missing in the order thermoplasmatales. the pto0232 gene from picrophilus torridus, a thermoacidophilic euryarchaeon, is shown to be a distant homologue of the prokaryotic type i coaa. the cloned gene clearly complements the poor growth of the tempe ...	2010	19854913
identification of catechin as one of the flavonoids from combretum albiflorum bark extract that reduces the production of quorum-sensing-controlled virulence factors in pseudomonas aeruginosa pao1.	quorum-sensing (qs) regulates the production of key virulence factors in pseudomonas aeruginosa and other important pathogenic bacteria. in this report, extracts of leaves and bark of combretum albiflorum (tul.) jongkind (combretaceae) were found to quench the production of qs-dependent factors in p. aeruginosa pao1. chromatographic fractionation of the crude active extract generated several active fractions containing flavonoids, as shown by their typical spectral features. purification and str ...	2010	19854927
production of cell-cell signalling molecules by bacteria isolated from human chronic wounds.	to (i) identify chronic wound bacteria and to test their ability to produce acyl-homoserine-lactones (ahls) and autoinducer-2 (ai-2) cell-cell signalling molecules and (ii) determine whether chronic wound debridement samples might contain these molecules.	2010	19840177
bioactive secondary metabolites from a new terrestrial streptomyces sp. tn262.	during our search for streptomyces spp. as new producers of bioactive secondary metabolites, the ethyl acetate extract of the new terrestrial streptomyces isolate tn262 delivered eight antimicrobially active compounds. they were identified as 1-acetyl-beta-carboline (1), tryptophol (2), cineromycin b (3), 2,3-dihydrocineromycin b (4), cyclo-(tyrosylprolyl) (5), 3-(hydroxyacetyl)-indole (6), brevianamide f (7), and cis-cyclo-(l-prolyl-l-leucyl) (8). three further metabolites were detected in the ...	2010	19842066
molecular events involved in cellular invasion by ehrlichia chaffeensis and anaplasma phagocytophilum.	ehrlichia chaffeensis and anaplasma phagocytophilum are obligatory intracellular bacteria that preferentially replicate inside leukocytes by utilizing biological compounds and processes of these primary host defensive cells. these bacteria incorporate cholesterol from the host for their survival. upon interaction with host monocytes and granulocytes, respectively, these bacteria usurp the lipid raft domain containing gpi-anchored protein to induce a series of signaling events that result in inte ...	2010	19836896
development of a qualitative, multiplex real-time pcr kit for screening of genetically modified organisms (gmos).	the number of commercially available genetically modified organisms (gmos) and therefore the diversity of possible target sequences for molecular detection techniques are constantly increasing. as a result, gmo laboratories and the food production industry currently are forced to apply many different methods to reliably test raw material and complex processed food products. screening methods have become more and more relevant to minimize the analytical effort and to make a preselection for furth ...	2010	19798485
identification and characterization of new luxr/luxi-type quorum sensing systems from metagenomic libraries.	quorum sensing (qs) cell-cell communication systems are utilized by bacteria to coordinate their behaviour according to cell density. several different types of qs signal molecules have been identified, among which acyl-homoserine lactones (ahls) produced by proteobacteria have been studied to the greatest extent. although qs has been studied extensively in cultured microorganisms, little is known about the qs systems of uncultured microorganisms and the roles of these systems in microbial commu ...	2010	19735279
elimination of the mycotoxin citrinin production in the industrial important strain monascus purpureus sm001.	the application of the high-producing pigments industrial strain monascus purpureus sm001 has been greatly limited by the synchronous production of mycotoxin citrinin. here we have tried both traditional mutagenesis and metabolic engineering methods to eliminate the production of citrinin. traditional chemical and physical mutagens were applied to induce mutagenesis, and a bio-screening method based on the antibacterial activity of citrinin against bacillus subtilis was designed to select mutant ...	2010	19699814
polar positioning of a conjugation protein from the integrative and conjugative element icebs1 of bacillus subtilis.	icebs1 is an integrative and conjugative element found in the chromosome of bacillus subtilis. icebs1 encodes functions needed for its excision and transfer to recipient cells. we found that the icebs1 gene cone (formerly ydde) is required for conjugation and that conjugative transfer of icebs1 requires a conserved atpase motif of cone. cone belongs to the hera/ftsk superfamily of atpases, which includes the well-characterized proteins ftsk, spoiiie, virb4, and vird4. we found that a cone-gfp (g ...	2010	19734305
roles of ile66 and ala107 of d-psicose 3-epimerase from agrobacterium tumefaciens in binding o6 of its substrate, d-fructose.	using site-directed mutagenesis, we investigated the roles of ile66 and ala107 of d: -psicose 3-epimerase from agrobacterium tumefaciens in binding o6 of its true substrate, d: -fructose. when ile66 was substituted with alanine, glycine, cysteine, leucine, phenylalanine, tryptophan, tyrosine or valine, all the mutants dramatically increased the k (m) for d: -tagatose but slightly decreased the k (m) for d: -fructose, indicating that ile66 is involved in substrate recognition. when ala107 was sub ...	2010	19728106
diversity, epidemiology, and genetics of class d beta-lactamases.	class d beta-lactamase-mediated resistance to beta-lactams has been increasingly reported during the last decade. those enzymes also known as oxacillinases or oxas are widely distributed among gram negatives. genes encoding class d beta-lactamases are known to be intrinsic in many gram-negative rods, including acinetobacter baumannii and pseudomonas aeruginosa, but play a minor role in natural resistance phenotypes. the oxas (ca. 150 variants reported so far) are characterized by an important ge ...	2010	19721065
expression of a plant defensin in rice confers resistance to fungal phytopathogens.	transgenic rice (oryza sativa l. cv. pusa basmati 1), overexpressing the rs-afp2 defensin gene from the raphanus sativus was generated by agrobacterium tumefaciens-mediated transformation. expression levels of rs-afp2 ranged from 0.45 to 0.53% of total soluble protein in transgenic plants. it was observed that constitutive expression of rs-afp2 suppresses the growth of magnaporthe oryzae and rhizoctonia solani by 77 and 45%, respectively. no effect on plant morphology was observed in the rs-afp2 ...	2010	19690975
detailed characterization of mirafiori lettuce virus-resistant transgenic lettuce.	lettuce big-vein disease is caused by mirafiori lettuce virus (milv), which is vectored by the soil-borne fungus olpidium brassicae. a milv-resistant transgenic lettuce line was developed through introducing inverted repeats of the milv coat protein (cp) gene. here, a detailed characterization study of this lettuce line was conducted by comparing it with the parental, non-transformed 'kaiser' cultivar. there were no significant differences between transgenic and non-transgenic lettuce in terms o ...	2010	19557540
molecular cloning and characterization of a novel glyoxalase i gene tagly i in wheat (triticum aestivum l.).	methylglyoxal is a kind of poisonous metabolite that can react with rna, dna and protein, which generally results in a number of side advert effects to cell. glyoxalase i is a member of glyoxalase system that can detoxify methylglyoxal. an est encoding a glyoxalase i was isolated from a ssh (suppression subtractive hybridization)-cdna library of wheat spike inoculated by fusarium graminearum. the corresponding full length gene, named tagly i, was cloned, sequenced and characterized. its genomic ...	2010	19513813
the reversed terminator of octopine synthase gene on the agrobacterium ti plasmid has a weak promoter activity in prokaryotes.	agrobacterium tumefaciens transfers dna from its ti plasmid to plant host cells. the genes located within the transferred dna of ti plasmid including the octopine synthase gene (ocs) are expressed in plant host cells. the 3'-flanking region of ocs gene, known as ocs terminator, is widely used as a transcriptional terminator of the transgenes in plant expression vectors. in this study, we found the reversed ocs terminator (3'-ocs-r) could drive expression of hygromycin phosphotransferase ii gene ...	2010	19669666
detection of different quorum-sensing signal molecules in a virulent edwardsiella tarda strain ltb-4.	the aim of this study was to elucidate the potential quorum-sensing (qs) signal molecules of an emerging pathogen (edwardsiella tarda strain ltb-4) of cultured turbot (scophthalmus maximus).	2010	19548884
expression of a hema gene from agrobacterium radiobacter in a rare codon optimizing escherichia coli for improving 5-aminolevulinate production.	the 5-aminolevulinate (ala) synthase gene (hema) from agrobacterium radiobacter zju-0121, which was cloned previously in our laboratory, contains several rare codons. to enhance the expression of this gene, escherichia coli rosetta(de3), which is a rare codon optimizer strain, was picked out as the host to construct an efficient recombinant strain. cell extracts of the recombinant e. coli were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under the appropriate conditions. ...	2010	18800199
an open-flower mutant of melilotus alba: potential for floral-dip transformation of a papilionoid legume with a short life cycle?	this paper describes an open-flower mutant, designated opf, that we discovered in a genetic screen of fast neutron bombardment mutants in an attempt at floral-dip transformation of melilotus alba (fabaceae; white sweetclover), an alternative papilionoid legume host for sinorhizobium meliloti. the opf mutant developed flowers with reflexed sepals and petals, thereby exposing the stamens and carpel, whereas wild-type sweetclover inflorescences developed closed flowers where the young stamens and c ...	2010	21622403
agrobacterium tumefaciens-mediated transformation as a tool for insertional mutagenesis in medicinal fungus cordyceps militaris.	cordyceps militaris is an insect-born fungus with various biological and pharmacological activities. the mutant library of c. militaris was constructed by improved agrobacterium tumefaciens-mediated transformation (atmt), for the ultimate identification of genes involved in isolate degeneration during fruiting body production. successful transformation of c. militaris jm4 by a. tumefaciens agl-1 carrying vector patmt1 was performed, with efficiency in the range of 30-600 transformants per 1×10(5 ...	2010	21354533
s-glycoprotein-like protein regulates defense responses in nicotiana plants against ralstonia solanacearum.	rsrga4 (for ralstonia solanacearum-responsive gene a4) encodes a polypeptide similar to s-locus glycoprotein (sgp) from brassica rapa and sgp-like proteins from ipomoea trifida and medicago truncatula. therefore, we designated rsrga4 as ntsglp (for nicotiana tabacum sgp-like protein) and nbsglp (its nicotiana benthamiana ortholog). nbsglp is expressed in root, leaf, petal, gynoecium, and stamen. expression of nbsglp was strongly induced by inoculation with an avirulent strain of r. solanacearum ...	2010	20118275
plasmid pami2 of paracoccus aminophilus jcm 7686 carries n,n-dimethylformamide degradation-related genes whose expression is activated by a luxr family regulator.	n,n-dimethylformamide (dmf), a toxic solvent used in the chemical industry, is frequently present in industrial wastes. plasmid pami2 (18.6 kb) of paracoccus aminophilus jcm 7686 carries genetic information which is crucial for methylotrophic growth of this bacterium, using dmf as the sole source of carbon and energy. besides a conserved backbone related to pagk84 of agrobacterium radiobacter k84, pami2 carries a three-gene cluster coding for the protein dmfr, which has sequence similarities to ...	2010	20118371
agroinfiltration reduces aba levels and suppresses pseudomonas syringae-elicited salicylic acid production in nicotiana tabacum.	agrobacterium tumefaciens strain gv3101 (pmp90) is widely used in transient gene expression assays, including assays to study pathogen effectors and plant disease resistance mechanisms. however, inoculation of a. tumefaciens gv3101 into nicotiana tabacum (tobacco) leaves prior to infiltration with pathogenic and non-host strains of pseudomonas syringae results in suppression of macroscopic symptoms when compared with leaves pre-treated with a buffer control.	2010	20126459
agrobacterium radiobacter bacteremia in a child with acute lymphoblastic leukemia.	agrobacteria are gram-negative tumorigenic plant pathogens that rarely cause infections in humans.	2010	20127221
agrobacterium type iv secretion system and its substrates form helical arrays around the circumference of virulence-induced cells.	the genetic transformation of plant cells by agrobacterium tumefaciens results from the transfer of dna and proteins via a specific virulence (vir) -induced type iv secretion system (t4ss). to better understand t4ss function, we analyzed the localization of its structural components and substrates by deconvolution fluorescence microscopy. gfp fusions to t4ss proteins with cytoplasmic tails, virb8 and vird4, or cytoplasmic t4ss substrate proteins, vird2, vire2, and virf, localize in a helical pat ...	2010	20133577
over-expression of superoxide dismutase exhibits lignification of vascular structures in arabidopsis thaliana.	the present study demonstrated that over-expression of copper-zinc superoxide dismutase (cu/zn-sod), an important enzyme scavenging reactive oxygen species, improved vascular structures through lignification and imparted tolerance to salt stress (nacl) in arabidopsis thaliana (arabidopsis; accession col-0). transgenic plants of arabidopsis were developed by over-expressing cytosolic cu/zn-sod from potentilla atrosanguinea under camv35s promoter via agrobacterium tumefaciens mediated transformati ...	2010	20138686
transgenic leucaena leucocephala expressing the rhizobium gene pyda encoding a meta-cleavage dioxygenase shows reduced mimosine content.	the use of the tree-legume leucaena leucocephala (leucaena), which contains high levels of proteins in its foliage, is limited due to the presence of the toxic free amino acid mimosine. the goal of this research was to develop transgenic leucaena with reduced mimosine content. two genes, pyda and pydb, encoding a meta-cleavage dioxygenase (ec 1.13.11.2) and a pyruvate hydrolase (ec 3.7.1.6), respectively, from the mimosine-degrading leucaena symbiont rhizobium sp. strain tal1145, were used to tr ...	2010	20138776
biochemical characterization of three putative atpases from a new type iv secretion system of aeromonas veronii plasmid pac3249a.	type four secretion systems (tfss) are bacterial macromolecular transport systems responsible for transfer of various substrates such as proteins, dna or protein-dna complexes. tfsss encode two or three atpases generating energy for the secretion process. these enzymes exhibit highest sequence conservation among type four secretion components.	2010	20144229
purification, crystallization and preliminary x-ray diffraction analysis of cif, a virulence factor secreted by pseudomonas aeruginosa.	the opportunistic pathogen pseudomonas aeruginosa secretes a protein that triggers the accelerated degradation of the cystic fibrosis transmembrane conductance regulator (cftr) in airway epithelial cells. this protein, which is known as the cftr inhibitory factor (cif), acts as a virulence factor and may facilitate airway colonization by p. aeruginosa. based on sequence similarity cif appears to be an epoxide hydrolase (eh), but it lacks several of the conserved features found in the active site ...	2010	20057063
catheter associated bloodstream infection caused by r. radiobacter.	rhizobium radiobacter is a gram negative bacillus that is infrequently recognized in clinical specimens but is emerging as an opportunistic human pathogen. infections due to rhizobium radiobacter are strongly related to the presence of foreign plastic material and effective treatment often requires removal of the device. we report a case of r. radiobacter bloodstream infection associated with a central venous catheter which was easily controlled by antimicrobial treatment and did not require rem ...	2010	20061769
a simplified and efficient method for transformation and gene tagging of ustilago maydis using frozen cells.	ustilago maydis is an important model fungal organism for diverse studies. little improvement has been made in the method for its transformation since the peg-mediated transfection of spheroplasts that was reported more than 20years ago. we have constructed binary t-dna vectors carrying hygromycin and nourseothricin resistance gene cassettes and have developed a highly efficient method for transformation of this fungus based on agrobacterium tumefaciens-mediated transformation (atmt). through a ...	2010	20079868
composite system mediates two-step dna uptake into helicobacter pylori.	the gram-negative gastric pathogen helicobacter pylori depends on natural transformation for genomic plasticity, which leads to host adaptation and spread of resistances. here, we show that h. pylori takes up covalently labeled fluorescent dna preferentially at the cell poles and that uptake is dependent on the type iv secretion system comb. by titration of external ph and detection of accessibility of the fluorophor by protons, we localized imported fluorescent dna in the periplasm. single mole ...	2010	20080542
the quorum-quenching n-acyl homoserine lactone acylase pvdq is an ntn-hydrolase with an unusual substrate-binding pocket.	in many gram-negative pathogens, their virulent behavior is regulated by quorum sensing, in which diffusible signals such as n-acyl homoserine lactones (ahls) act as chemical messaging compounds. enzymatic degradation of these diffusible signals by, e.g., lactonases or amidohydrolases abolishes ahl regulated virulence, a process known as quorum quenching. here we report the first crystal structure of an ahl amidohydrolase, the ahl acylase pvdq from pseudomonas aeruginosa. pvdq has a typical alph ...	2010	20080736
expanding small-molecule functional metagenomics through parallel screening of broad-host-range cosmid environmental dna libraries in diverse proteobacteria.	the small-molecule biosynthetic diversity encoded within the genomes of uncultured bacteria is an attractive target for the discovery of natural products using functional metagenomics. phenotypes commonly associated with the production of small molecules, such as antibiosis, altered pigmentation, or altered colony morphology, are easily identified from screens of arrayed metagenomic library clones. however, functional metagenomic screening methods are limited by their intrinsic dependence on a h ...	2010	20081001
the receiver domain of hybrid histidine kinase vira: an enhancing factor for vir gene expression in agrobacterium tumefaciens.	the plant pathogen agrobacterium tumefaciens expresses virulence (vir) genes in response to chemical signals found at the site of a plant wound. vira, a hybrid histidine kinase, and its cognate response regulator, virg, regulate vir gene expression. the receiver domain at the carboxyl end of vira has been described as an inhibitory element because its removal increased vir gene expression relative to that of full-length vira. however, experiments that characterized the receiver region as an inhi ...	2010	20081031
a candidate gene osapc6 of anaphase-promoting complex of rice identified through t-dna insertion.	a dwarf mutant (oryza sativa anaphase-promoting complex 6 (osapc6)) of rice cultivar basmati 370 with 50% reduced plant height as compared to the wild type was isolated by agrobacterium tumefaciens-mediated transformation using hm(r) ds cassette. this mutant was found to be insensitive to exogenous gibberellic acid (ga(3)) application. homozygous mutant plants showed incomplete penetrance and variable expressivity for plant height and pleiotropic effects including gibberellic acid insensitivity, ...	2010	20091079
inhibitors of the pseudomonas aeruginosa quorum-sensing regulator, qscr.	qscr is a quorum-sensing (qs) signal receptor that controls expression of virulence genes in the prevalent opportunistic pathogen, pseudomonas aeruginosa. unlike the previously reported luxr-type qs receptor proteins, that is, lasr and trar, qscr can be obtained as an apo-protein that can reversibly form an active complex in vitro with its cognate signal molecule, 3-oxododecanoyl-homoserine lactone (3oc12-hsl), and subsequently bind to target promoter dna sequences. to search for potential qs in ...	2010	20091741
efficient agrobacterium tumefaciens-mediated transformation and regeneration of garlic (allium sativum) immature leaf tissue.	transgenic garlic (allium sativum) plants have been recovered directly from immature leaf material by selective culture following agrobacterium-mediated transformation. this method involved the use of a binary vector containing the mgfp-er reporter gene and hpt selectable marker, and followed a similar protocol developed previously for the transformation of immature onion embryos. the choice of tissue and post-transformation selection procedure resulted in a large increase in recovery of transge ...	2010	20099065
genetic transformation of carnation (dianthus caryophylus l.).	this chapter describes a rapid and efficient protocol for explant preparation and genetic transformation of carnation. node explants from greenhouse-grown plants and leaf explants from in vitro plants are infected with agrobacterium tumefaciens agl0 harboring pkt3 plasmid, consisting of gus and nptii genes. explant preparation is an important factor to obtain the transformed plants. the gus-staining area was located only on the cut end of explants and only explants with a cut end close to the co ...	2010	20099093
validation of a newly developed hexaplex real-time pcr assay for screening for presence of gmos in food, feed and seed.	for years, an increasing number and diversity of genetically modified plants has been grown on a commercial scale. the need for detection and identification of these genetically modified organisms (gmos) calls for broad and at the same time flexible high throughput testing methods. here we describe the development and validation of a hexaplex real-time polymerase chain reaction (pcr) screening assay covering more than 100 approved gmos containing at least one of the gmo targets of the assay. the ...	2010	20101506
the green fluorescent protein as an efficient selection marker for agrobacterium tumefaciens-mediated transformation in hevea brasiliensis (müll. arg).	an efficient genetic transformation procedure using a recombinant green fluorescent protein (gfp) has been developed in hevea brasiliensis clone pb260. transformation experiments have been performed using an agrobacterium tumefaciens binary vector harbouring both uida and s65t-gfp reporter genes in order to compare selection methods using glucuronidase assay (gus activity) and paromomycin resistance, gfp activity and paromomycin resistance, or gfp activity only. at transient level, the number of ...	2010	20306052
using high competent shoot apical meristems of cockscomb as explants for studying function of asymmetric leaves2-like11 (asl11) gene of arabidopsis.	though shoot apical meristems (sams) commonly exhibit low or no competence for transformation, the potent regeneration of this tissue merits further research. especially, when shoot regeneration is recalcitrant using other tissues as explants, sam probably is an excellent selection. in cockscomb plants, using sams from seedlings obtained from ms medium with 0.5 mg l(-1) 6-ba as explants, high frequency of transformation (approximate 20%) is obtained; whereas control sams performed poorly for tra ...	2010	20306306
light-induced activation of bacterial phytochrome agp1 monitored by static and time-resolved ftir spectroscopy.	phytochromes, which regulate many biological processes in plants, bacteria, and fungi, can exist in two stable states, pr and pfr, that can be interconverted by light, via a number of intermediates such as meta-rc. herein we employ ftir spectroscopy to study the pr-to-pfr conversion of the bacteriophytochrome agp1 from agrobacterium tumefaciens. static ftir pfr/pr and meta-rc/pr difference spectra are disentangled in terms of cofactor and protein structural changes. guided by dft calculations on ...	2010	20333618
induction of chromosomal inversion by integration of t-dna in the rice genome.	transfer dna (t-dna) of agrobacterium tumefaciens integration in the plant genome may lead to rearrangements of host plant chromosomal fragments, including inversions. however, there is very little information concerning the inversion. the present study reports a transgenic rice line selected from a t-dna tagged population, which displays a semi-dwarf phenotype. molecular analysis of this mutant indicated an insertion of two tandem copies of t-dna into a locus on the rice genome in a head to tai ...	2010	20347828
agrobacterium tumefaciens type iv secretion protein virb3 is an inner membrane protein and requires virb4, virb7, and virb8 for stabilization.	agrobacterium tumefaciens virb proteins assemble a type iv secretion apparatus and a t-pilus for secretion of dna and proteins into plant cells. the pilin-like protein virb3, a membrane protein of unknown topology, is required for the assembly of the t-pilus and for t-dna secretion. using phoa and green fluorescent protein (gfp) as periplasmic and cytoplasmic reporters, respectively, we demonstrate that virb3 contains two membrane-spanning domains and that both the n and c termini of the protein ...	2010	20348257