Publications

evolutionary diversity of ketoacyl synthases in cellulolytic myxobacterium sorangium.	the diversity of type i polyketide synthases (pkss) in cellulolytic myxobacterium sorangium was explored by assaying the ketoacyl synthases (kss) in 10 sorangium strains with two degenerate primer sets and 64 different ks fragments were obtained. for their deduced amino acid sequences, eight were identical to three known kss from sorangium and magnetospirillum, while the others showed 54-83% identities to the modular ks domains reported from various microorganisms. parts of the sorangium kss tig ...	2007	16899349
reconstitution of the myxothiazol biosynthetic gene cluster by red/et recombination and heterologous expression in myxococcus xanthus.	although many secondary metabolites exhibiting important pharmaceutical and agrochemical activities have been isolated from myxobacteria, most of these microorganisms remain difficult to handle genetically. to utilize their metabolic potential, heterologous expression methodologies are currently being developed. here, the red/et recombination technology was used to perform all required gene cluster engineering steps in escherichia coli prior to the transfer into the chromosome of the heterologou ...	2006	16997979
a type ii polyketide synthase from the gram-negative bacterium stigmatella aurantiaca is involved in aurachin alkaloid biosynthesis.		2007	17335090
from genetic diversity to metabolic unity: studies on the biosynthesis of aurafurones and aurafuron-like structures in myxobacteria and streptomycetes.	the myxobacterial polyketide secondary metabolites aurafuron a and b were identified by genome mining in the myxobacterial strain stigmatella aurantiaca dw4/3-1. the compounds contain an unusual furanone moiety and resemble metabolites isolated from soil-dwelling and marine actinobacteria, a fungus and mollusks. we describe here the cloning and functional analysis of the aurafuron biosynthetic gene cluster, including site-directed mutagenesis and feeding studies using labeled precursors. the pol ...	2007	17919655
mutasynthesis-derived myxalamids and origin of the isobutyryl-coa starter unit of myxalamid b.	myxalamids are potent inhibitors of the eukaryotic electron transport chain produced by different myxobacteria. here, we describe the identification of the myxalamid biosynthesis gene cluster from myxococcus xanthus. additionally, new myxalamids (5-13) have been obtained by mutasynthesis from bkd mutants of m. xanthus and stigmatella aurantiaca. moreover, as these bkd mutants are still able to produce myxalamid b (2), the origin of the isobutyryl-coa (ib-coa) starter unit required for its biosyn ...	2007	17955482
myxochelin biosynthesis: direct evidence for two- and four-electron reduction of a carrier protein-bound thioester.	microorganisms produce small molecules known as siderophores to scavenge iron from the environment. insight into iron acquisition in myxobacteria has been provided recently by the sequencing of the gene cluster for the catecholate myxochelins a and b, from the myxobacterium stigmatella aurantiaca sg a15. the gene cluster contains enzymes (mxccdef) for assembly of 2,3-dihydroxybenzoic acid (dhba), an amino transferase, mxcl, and a nonribosomal peptide synthetase (nrps) subunit, mxcg. in the propo ...	2008	18498160
efficient transfer of two large secondary metabolite pathway gene clusters into heterologous hosts by transposition.	horizontal gene transfer by transposition has been widely used for transgenesis in prokaryotes. however, conjugation has been preferred for transfer of large transgenes, despite greater restrictions of host range. we examine the possibility that transposons can be used to deliver large transgenes to heterologous hosts. this possibility is particularly relevant to the expression of large secondary metabolite gene clusters in various heterologous hosts. recently, we showed that the engineering of ...	2008	18701643
dkxanthene biosynthesis--understanding the basis for diversity-oriented synthesis in myxobacterial secondary metabolism.	the dkxanthenes are a family of yellow pigments which play a critical role in myxobacterial development. thirteen unique structures from myxococcus xanthus dk1622 differ in the length of their characteristic polyene functionality, as well as the extent of methyl branching. we aimed to understand the mechanistic basis for this "molecular promiscuity" by analyzing the gene cluster in dk1622, and comparing it to the dkxanthene biosynthetic locus in a second myxobacterium, stigmatella aurantiaca dw4 ...	2008	18721748
myxochromide b3, a new member of the myxochromide family of secondary metabolites.	myxochromides are cyclic depsipeptides with an unsaturated polyketide side chain, which have been reported from different myxobacterial species, e.g., myxococcus xanthus and stigmatella aurantiaca. to date, myxochromides are subdivided into the groups a and s, according to their peptidic core structure. the peptide moiety of the new myxochromide b3 (1), which was isolated from a myxobacterial strain of the genus myxococcus, differs from that of myxochromides a and s. compound 1 thus is the first ...	2008	18803421
eukaryotic-like protein kinases in the prokaryotes and the myxobacterial kinome.	ser/thr/tyr kinases, which together comprise a major class of regulatory proteins in eukaryotes, were not believed to play an important role in prokaryotes until recently. however, our analysis of 626 prokaryotic genomes reveals that eukaryotic-like protein kinases (elks) are found in nearly two-thirds of the sequenced strains. we have identified 2697 elks, most of which are encoded by multicellular strains of the phyla proteobacteria (myxococcales), actinobacteria, cyanobacteria, and chloroflex ...	2008	18836084
isolation and biosynthesis of aurachin p and 5-nitroresorcinol from stigmatella erecta.	the isolation of aurachin p (2) from stigmatella erecta strain pd e32 is described. spectroscopic data, in particular nmr data, indicate it is 1'-hydroxyaurachin a with a 1'r,2's,3'r relative configuration. in addition, a further compound, 5-nitroresorcinol (4a), was isolated and identified as a novel natural product. feeding of (13)c- and (15)n-labeled precursors indicated this was synthesized solely from glucose and ammonia. to account for the labeling pattern, phloroglucinol (8) is postulated ...	2008	18986196
biosynthesis of aurachins a-l in stigmatella aurantiaca: a feeding study.	the isolation of aurachins a-l (1-11) from stigmatella aurantiaca strain sg a15 is described. their structures and relative configurations were deduced from spectroscopic data, in particular nmr. three structural types were identified: a-type aurachins (1, 2, 6) are c-3 oxygen-substituted quinolines carrying a farnesyl residue on c-4, c-type aurachins (3, 4, 7-11) are c-4 oxygen-substituted quinolines carrying a farnesyl residue on c-3, and c-type aurachin e (5) has a [1,1a,8,d]imidazoloquinolin ...	2008	18989924
novel expression hosts for complex secondary metabolite megasynthetases: production of myxochromide in the thermopilic isolate corallococcus macrosporus gt-2.	abstract: although many secondary metabolites with diverse biological activities have been isolated from myxobacteria, most strains of these biotechnologically important gliding prokaryotes remain difficult to handle genetically. in this study we describe the new fast growing myxobacterial thermophilic isolate gt-2 as a heterologous host for the expression of natural product biosynthetic pathways isolated from other myxobacteria. according to the results of sequence analysis of the 16s rdna, thi ...	2009	19126236
a quinoline antibiotic from rhodococcus erythropolis jcm 6824.	a new quinoline antibiotic, aurachin re, was isolated and identified from a culture broth of rhodococcus erythropolis jcm 6824. the aurachin re structure was determined based on nmr and mass spectrometric analysis. the structure is similar to that of aurachin c antibiotics that have been identified from stigmatella aurantiaca. compared to aurachin c, however, aurachin re exhibits a wide and strong antimicrobial spectrum against both high- and low-gc gram-positive bacteria.	2008	19168983
phylogenetic analysis of the triterpene cyclase protein family in prokaryotes and eukaryotes suggests bidirectional lateral gene transfer.	functional constraints to modifications in triterpene cyclase amino acid sequences make them good candidates for evolutionary studies on the phylogenetic relatedness of these enzymes in prokaryotes as well as in eukaryotes. in this study, we used a set of identified triterpene cyclases, a group of mainly bacterial squalene cyclases and a group of predominantly eukaryotic oxidosqualene cyclases, as seed sequences to identify 5288 putative triterpene cyclase homologues in publicly available databa ...	2009	19207562
biosynthesis of 2-hydroxy and iso-even fatty acids is connected to sphingolipid formation in myxobacteria.	2-hydroxy fatty acids can be found in several different organisms, including bacteria. in this study, we have studied the biosynthesis of 2-hydroxy fatty acids in the myxobacteria myxococcus xanthus and stigmatella aurantiaca, resulting in the identification of a family of stereospecific fatty acid alpha-hydroxylases. although the stereospecificities of the hydroxylases differ between these two species, they share a common function in supporting fatty acid alpha-oxidation; that is, the oxidative ...	2009	19575369
non-modular polyketide synthases in myxobacteria.	myxobacteria are prolific producers of a wide variety of secondary metabolites. the vast majority of these compounds are complex polyketides which are biosynthesised by multimodular polyketide synthases (pkss). in contrast, few myxobacterial metabolites isolated to date are derived from non-modular pkss, in particular type iii pkss. this review reports our progress on the characterisation of type iii pkss in myxobacteria. we also summarize current knowledge on bacterial type iii pkss, with a spe ...	2009	19586645
functional equivalence of hmga- and histone h1-like domains in a bacterial transcriptional factor.	histone h1 and high-mobility group a (hmga) proteins compete dynamically to modulate chromatin structure and regulate dna transactions in eukaryotes. in prokaryotes, hmga-like domains are known only in myxococcus xanthus card and its stigmatella aurantiaca ortholog. these have an n-terminal module absent in hmga that interacts with carg (a zinc-associated factor that does not bind dna) to form a stable complex essential in regulating multicellular development, light-induced carotenogenesis, and ...	2009	19666574
molecular and structural basis of metabolic diversity mediated by prenyldiphosphate converting enzymes.	general thermodynamic calculations using the semiempiric pm3 method have led to the conclusion that prenyldiphosphate converting enzymes require at least one divalent metal cation for the activation and cleavage of the diphosphate-prenyl ester bond, or they must provide structural elements for the efficient stabilization of the intermediate prenyl cation. the most important common structural features, which guide the product specificity in both terpene synthases and aromatic prenyl transferases ...	2009	19878958
insights into multienzyme docking in hybrid pks-nrps megasynthetases revealed by heterologous expression and genetic engineering.		2010	20391455
comparative genomic analysis of fruiting body formation in myxococcales.	genetic programs underlying multicellular morphogenesis and cellular differentiation are most often associated with eukaryotic organisms, but examples also exist in bacteria such as the formation of multicellular, spore-filled fruiting bodies in the order myxococcales. most members of the myxococcales undergo a multicellular developmental program culminating in the formation of spore-filled fruiting bodies in response to starvation. to gain insight into the evolutionary history of fruiting body ...	2010	21037205
fatty acid-related phylogeny of myxobacteria as an approach to discover polyunsaturated omega-3/6 fatty acids.	in an analysis of 47 aerobic myxobacterial strains, representing 19 genera in suborders cystobacterineae, nannocystineae, sorangiineae, and a novel isolate, "aetherobacter" sbsr008, an enormously diverse array of fatty acids (fas) was found. the distribution of straight-chain fatty acids (scfas) and branched-chain fatty acids (bcfas) supports the reported clustering of strains in the phylogenetic tree based on 16s rrna genes. this finding additionally allows the prediction and assignment of the ...	2011	21317327
investigation of cytochromes p450 in myxobacteria: excavation of cytochromes p450 from the genome of sorangium cellulosum so ce56.	the exploitation of cytochromes p450 for novel biotechnological application and for the investigation of their physiological function is of great scientific interest in this post genomic era, where an extraordinary biodiversity of p450 genes has been derived from all forms of life. the study of p450s in the myxobacterium sorangium cellulosum strain so ce56, the producer of novel secondary metabolites of pharmaceutical interest is the research topic, in which we were engaged since the beginning o ...	2011	21521637
auaa, a membrane-bound farnesyltransferase from stigmatella aurantiaca, catalyzes the prenylation of 2-methyl-4-hydroxyquinoline in the biosynthesis of aurachins.	aurachins are quinoline alkaloids isolated from the myxobacterium stigmatella aurantiaca. they are substituted with an isoprenoid side chain and act as potent inhibitors in the electron transport chain. a biosynthetic gene cluster that contains at least five genes (auaa-auae) has been identified for aurachin biosynthesis. in this study, auaa, the gene encoding a putative prenyltransferase of 326 amino acids, was cloned and overexpressed in escherichia coli. biochemical investigations showed that ...	2011	21671333
unprecedented anthranilate priming involving two enzymes of the acyl adenylating superfamily in aurachin biosynthesis.	biosynthesis of many polyketide-derived secondary metabolites is initiated by incorporating starter units other than acetate. thus, understanding their priming mechanism is of importance for metabolic engineering. insight into the loading process of anthranilate into the biosynthetic pathway for the quinoline alkaloids aurachins has been provided by the sequencing of a partial biosynthetic gene cluster in the myxobacterium stigmatella aurantiaca. the cluster encodes a predicted aryl:coa ligase a ...	2011	21770425
Completing the puzzle of aurachin biosynthesis in Stigmatella aurantiaca Sg a15.	The aurachins are a family of secondary metabolites, with the main members aurachin A, B, C, and D, produced by the myxobacterium Stigmatella aurantiaca Sg a15. These isoprenoid quinoline alkaloids are classified as A-type or C-type aurachins according to the position of the farnesyl residue either at C4 or C3 of the quinoline core, respectively. Previous feeding studies revealed that the C-type aurachins are converted to A-type aurachins by late stage tailoring reactions. While the core gene cl ...	2011	21979787
evolution of antifreeze protein genes in the diatom genus fragilariopsis: evidence for horizontal gene transfer, gene duplication and episodic diversifying selection.	hypotheses about horizontal transfer of antifreeze protein genes to ice-living diatoms were addressed using two different statistical methods available in the program prunier. the role of diversifying selection in driving the differentiation of a set of antifreeze protein genes in the diatom genus fragilariopsis was also investigated. four horizontal gene transfer events were identified. two of these took place between two major eukaryote lineages, that is from the diatom chaetoceros neogracile ...	2011	22253534