Publications

design, synthesis, and biological testing of novel naphthoquinones as substrate-based inhibitors of the quinol/fumarate reductase from wolinella succinogenes.	novel naphthoquinones were designed, synthesized, and tested as substrate-based inhibitors against the membrane-embedded protein quinol/fumarate reductase (qfr) from wolinella succinogenes, a target closely related to qfrs from the human pathogens helicobacter pylori and campylobacter jejuni. for a better understanding of the hitherto structurally unexplored substrate binding pocket, a structure-activity relationship (sar) study was carried out. analogues of lawsone (2-hydroxy-1,4-naphthoquinone ...	2013	24251984
identification of a broad family of lipid a late acyltransferases with non-canonical substrate specificity.	most gram-negative organisms produce lipopolysaccharide (lps), a complex macromolecule anchored to the bacterial membrane by the lipid a moiety. lipid a is synthesized via the raetz pathway, a conserved nine-step enzymatic process first characterized in escherichia coli. the epsilonproteobacterium helicobacter pylori uses the raetz pathway to synthesize lipid a; however, only eight of nine enzymes in the pathway have been identified in this organism. here, we identify the missing acyltransferase ...	2014	24372821
interaction of dichloromethane (methylene chloride) with the nitrous oxide reductase from wolinella succinogenes.	nitrous oxide reductase from wolinella succinogenes was tested for benzyl viologen cation (bv(+))-chlorinated methane oxidoreductase activity, using di-, tri- and tetra-chloromethanes, and for the inhibition of bv(+)-n2o oxidoreductase activity by these chloromethanes. no bv(+)-chlorinated methane oxidoreductase activity was detected. any such activity, if it exists, must be less than 0.1% of the bv(+)-n2o oxidoreductase activity of the enzyme. inhibition of the bv(+)-n2o oxidoreductase activity ...	1993	24420116
presence and analysis of plasmids in human and animal associated arcobacter species.	in this study, we report the screening of four arcobacter species for the presence of small and large plasmids. plasmids were present in 9.9% of the 273 examined strains. one arcobacter cryaerophilus and four arcobacter butzleri plasmids were selected for further sequencing. the size of three small plasmids isolated from a. butzleri and the one from a. cryaerophilus strains ranged between 4.8 and 5.1 kb, and the size of the large plasmid, isolated from a. butzleri, was 27.4 kbp. the g+c content ...	2014	24465575
differentiation of non-pylori helicobacter species based on pcr-restriction fragment length polymorphism of the 23s rrna gene.	phenotypic identification of non-pylori helicobacter species has always been problematic and time-consuming in comparison with many other bacteria. we developed a rapid two-step identification assay based on pcr-restriction fragment length polymorphism (pcr-rflp) analysis of the 23s rrna gene for differentiating between non-pylori helicobacter species. a new genus-specific primer pair based on all available complete and partial 23s rrna sequences of helicobacter species was designed. in silico r ...	2014	24493015
production and consumption of nitrous oxide in nitrate-ammonifying wolinella succinogenes cells.	global warming is moving more and more into the public consciousness. besides the commonly mentioned carbon dioxide and methane, nitrous oxide (n2o) is a powerful greenhouse gas in addition to its contribution to depletion of stratospheric ozone. the increasing concern about n2o emission has focused interest on underlying microbial energy-converting processes and organisms harbouring n2o reductase (nosz), such as denitrifiers and ammonifiers of nitrate and nitrite. here, the epsilonproteobacteri ...	2014	24781903
storage, transport, release: heme versatility in nitrite reductase electron transfer studied by molecular dynamics simulations.	using molecular dynamics simulations of the thermodynamic integration type, we study the energetics and kinetics of electron transfer through the nitrite reductase enzyme of sulfurospirillum deleyianum, wolinella succinogenes and campylobacter jejuni. in all of these five-heme proteins, the storage of an even number of electrons within a monomeric chain is thermodynamically favoured. kinetically, two of these electrons are usually transferred almost simultaneously towards the active site. althou ...	2015	25579411
an unconventional anaerobic membrane protein production system based on wolinella succinogenes.	in cases where membrane protein production attempts in more conventional escherichia coli-based systems have failed, a solution is to resort to a system based on the nonpathogenic epsilon-proteobacterium wolinella succinogenes. this approach has been demonstrated to be successful for structural and mechanistic analyses not only for homologous production of w. succinogenes membrane proteins but also for the heterologous production of membrane protein complexes from the human pathogens helicobacte ...	2015	25857779
three transcription regulators of the nss family mediate the adaptive response induced by nitrate, nitric oxide or nitrous oxide in wolinella succinogenes.	sensing potential nitrogen-containing respiratory substrates such as nitrate, nitrite, hydroxylamine, nitric oxide (no) or nitrous oxide (n2 o) in the environment and subsequent upregulation of corresponding catabolic enzymes is essential for many microbial cells. the molecular mechanisms of such adaptive responses are, however, highly diverse in different species. here, induction of periplasmic nitrate reductase (nap), cytochrome c nitrite reductase (nrf) and cytochrome c n2 o reductase (cnos) ...	2016	26395430
nitrate and inhibition of ruminal methanogenesis: microbial ecology, obstacles, and opportunities for lowering methane emissions from ruminant livestock.	ruminal methane production is among the main targets for greenhouse gas (ghg) mitigation for the animal agriculture industry. many compounds have been evaluated for their efficacy to suppress enteric methane production by ruminal microorganisms. of these, nitrate as an alternative hydrogen sink has been among the most promising, but it suffers from variability in efficacy for reasons that are not understood. the accumulation of nitrite, which is poisonous when absorbed into the animal's circulat ...	2016	26904008
the modified heparin-binding l-asparaginase of wolinella succinogenes.	the modified asparaginase was79 was derived from the recombinant wild-type l-asparaginase of wolinella succinogenes. the was79 contains the amino acid substitutions v23q and k24t responsible for the resistance to trypsinolysis and the n-terminal heparin-binding peptide krkkkgkglgkkr responsible for the binding to heparin and tumor k562 cells in vitro. when tested on a mouse model of fischer lymphadenosis l5178y, therapeutic efficacy of was79 was significantly higher than that of reference enzyme ...	2016	27198565
unique and universal features of epsilonproteobacterial origins of chromosome replication and dnaa-dnaa box interactions.	in bacteria, chromosome replication is initiated by the interaction of the initiator protein dnaa with a defined region of a chromosome at which dna replication starts (oric). while dnaa proteins share significant homology regardless of phylogeny, oric regions exhibit more variable structures. the general architecture of orics is universal, i.e., they are composed of a cluster of dnaa binding sites, a dna-unwinding element, and sequences that bind regulatory proteins. however, detailed structure ...	2016	27746772
tsdc, a unique lipoprotein from wolinella succinogenes that enhances tetrathionate reductase activity of tsda.	the diheme cytochromes c of the widespread tsda family are bifunctional thiosulfate dehydrogenase/tetrathionate reductases. here, biochemical information was collected about tsda from the epsilonproteobacterium wolinella succinogenes (wstsda). the situation in w. succinogenes is unique since tsda is closely associated with the unprecedented lipoprotein tsdc encoded immediately downstream of tsda in the same direction of transcription. wstsda purified from escherichia coli catalyzed both thiosulf ...	2017	28062520
the differential ability of asparagine and glutamine in promoting the closed/active enzyme conformation rationalizes the wolinella succinogenes l-asparaginase substrate specificity.	many side effects of current fda-approved l-asparaginases have been related to their secondary l-glutaminase activity. the wolinella succinogenes l-asparaginase (woa) has been reported to be l-glutaminase free, suggesting it would have fewer side effects. unexpectedly, the woa variant with a proline at position 121 (woa-p121) was found to have l-glutaminase activity in contrast to uniprot entry p50286 (woa-s121) that has a serine residue at this position. towards understanding how this residue i ...	2017	28139703
a class c radical s-adenosylmethionine methyltransferase synthesizes 8-methylmenaquinone.	the membranous quinone/quinol pool is essential to the majority of life forms and has been widely used as an important biomarker in microbial taxonomy. in the anaerobic world, the most important quinones are menaquinone (mk) and a methylated form of mk, designated methylmenaquinone (mmk), which is anticipated to serve specifically in low-potential electron transport chains involved in anaerobic respiration. however, it has remained unclear how mmk is generated. here, we show that a novel enzyme ...	2017	28164386
[suppression of telomerase activity leukemic cells by mutant forms of rhodospirillum rubrum l-asparaginase].	the active and stable mutant forms of short chain cytoplasmic l-asparaginase type i of rhodospirillum rubrum (rra): rra+n17, d60k, f61l, rra+n17, a64v, e67k, rra+n17, e149r, v150p, rrae149r, v150p and rrae149r, v150p, f151t were obtained by the method of site-directed mutagenesis. it is established that variants rra-n17, e149r, v150p, f151t and rrаe149r, v150p are capable to reduce an expression htert subunit of telomerase and, hence, activity of telomeres in jurkat cells, but not in cellular ly ...	2017	28251953
model-based quantification of metabolic interactions from dynamic microbial-community data.	an important challenge in microbial ecology is to infer metabolic-exchange fluxes between growing microbial species from community-level data, concerning species abundances and metabolite concentrations. here we apply a model-based approach to integrate such experimental data and thereby infer metabolic-exchange fluxes. we designed a synthetic anaerobic co-culture of clostridium acetobutylicum and wolinella succinogenes that interact via interspecies hydrogen transfer and applied different envir ...	2017	28278266
molecular cloning of rhodanese gene from soil metagenome of cold desert of north-west himalayas: sequence and structural features of the rhodanese enzyme.	rhodanese is a multifunctional, sulfur transferase that catalyzes the detoxification of cyanide by sulphuration in a double displacement (ping pong) mechanistic reaction. in the present study, small-insert metagenomic library from soil sample collected from ladakh (3,000-3,600 m.a.s.l) in northwestern himalayas, india was constructed. function-driven screening of ~8,500 colonies led to the isolation of one esterase-positive clone (clone-est) harboring 2.43 kb insert. sequence analysis of the ins ...	2015	28324556
epsilonproteobacterial hydroxylamine oxidoreductase (εhao): characterization of a 'missing link' in the multihaem cytochrome c family.	members of the multihaem cytochrome c (mcc) family such as pentahaem cytochrome c nitrite reductase (nrfa) or octahaem hydroxylamine oxidoreductase (hao) are involved in various microbial respiratory electron transport chains. some members of the hao subfamily, here called εhao proteins, have been predicted from the genomes of nitrate/nitrite-ammonifying bacteria that usually lack nrfa. here, εhao proteins from the host-associated epsilonproteobacteria campylobacter fetus and campylobacter curvu ...	2017	28388834