Publications

biosynthetic pathways of the osmolytes n epsilon-acetyl-beta-lysine, beta-glutamine, and betaine in methanohalophilus strain fdf1 suggested by nuclear magnetic resonance analyses.	methanohalophilus strain fdf1 synthesizes beta-glutamine, betaine, and n epsilon-acetyl-beta-lysine as osmoprotective agents when the cells are grown in high external concentrations of nacl. nuclear magnetic resonance spectroscopic analyses of 13ch3oh-12co2 label incorporation by the cells provide information on the biosynthetic pathways of these organic osmolytes. the labeling studies indicate that methanohalophilus strain fdf1 produces glutamate and beta-glutamine via a partial oxidative krebs ...	1992	1400220
glycine betaine and potassium ion are the major compatible solutes in the extremely halophilic methanogen methanohalophilus strain z7302.	methanohalophilus strain z7302 was previously isolated from a hypersaline environment and grows over a range of nacl concentrations from 1.7 to 4.4 m. we examined the relationships between cell growth rate, cell volume, and intracellular solute concentrations with increasing salinity. this extremely halophilic methanogen synthesized three zwitterionic compounds, beta-glutamine, n epsilon-acetyl-beta-lysine, and glycine betaine, and also accumulated potassium ion as compatible solutes to balance ...	1992	1429470
mode of sodium ion action on methanogenesis and atpase of the moderate halophilic methanogenis bacterium methanohalophilus halophilus.	cells of methanohalophilus halophilus swelled when exposed to hypotonic solutions of nacl at ph 7.0. the swelling of the cells ceased in the presence of mg2+. methane formation by non-growing cells was strongly dependent on the nacl concentration. among other monovalent and divalent cations only li+ and mg2+ could partly substitute for a specific function of sodium ions. the artificial na+/h+ antiporter, monensin, exerted a strong inhibitory effect on methane formation from methylamine. the memb ...	1992	1532942
detection of the osmoregulator betaine in methanogens.	trimethyl glycine (glycine betaine) was detected by 13c nuclear magnetic resonance spectroscopy at high intracellular concentrations in several methanogens (methanogenium cariaci, "methanogenium anulus" an9, methanohalophilus zhilinae, methanohalophilus mahii, and methanococcus voltae) grown on marine media containing yeast extract. 13c labeling studies with methanogenium cariaci suggested that the betaine which accumulated inside the cells was not synthesized de novo but was transported in from ...	1990	2306094
taxonomic description of methanococcoides euhalobius and its transfer to the methanohalophilus genus.	a sequence analysis of the 16s-rrna of methanococcoides euhalobius revealed that this organism was highly related to members of the genus methanohalophilus. on the basis of sequence data, an oligonucleotide probe specific to methanohalophilus species was designed. hybridization studies with this probe confirmed close relationship of methanococcoides euhalobius to methanohalophilus species. therefore, we propose that methanococcoides euhalobius should be transferred to the genus methanohalophilus ...	1997	9195005
methanocalculus halotolerans gen. nov., sp. nov., isolated from an oil-producing well.	two irregular coccoid methanogens designated sebr 4845t and fr1t were isolated from an oilfield in alsace, france. strain sebr 4845t (t = type strain) is a hydrogenotrophic halotolerant methanogen, which grows optimally at 5% naci (w/v) and tolerates up to 12% naci. it does not use methylated compounds and therefore cannot be ascribed to any of the known genera of the halophilic methylotrophic methanogens. it differs from hydrogenotrophic members of the orders methanococcales and methanomicrobia ...	1998	9734036
diversity of extremely halophilic bacteria.	in this review, the history of the classification of the family halobacteriaceae, the extremely halophilic aerobic archaea, is reviewed with some emphasis on the recently described new genera halobaculum, halorubrum, natrialba, natronomonas, and "haloterrigena." speculation is made about the evolutionary relationship between members of the halobacteriaceae and the extremely halophilic, anaerobic methanogens of the genera methanohalobium and methanohalophilus. efforts to find missing links betwee ...	1998	9783176
regulatory factors associated with synthesis of the osmolyte glycine betaine in the halophilic methanoarchaeon methanohalophilus portucalensis.	the halophilic methanoarchaeon methanohalophilus portucalensis can synthesize de novo and accumulate beta-glutamine, nepsilon-acetyl-beta-lysine, and glycine betaine (betaine) as compatible solutes (osmolytes) when grown at elevated salt concentrations. both in vivo and in vitro betaine formation assays in this study confirmed previous nuclear magnetic resonance 13c-labelling studies showing that the de novo synthesis of betaine proceeded from glycine, sarcosine, and dimethylglycine to form beta ...	1999	9925623
isolation and characterization of methanomethylovorans hollandica gen. nov., sp. nov., isolated from freshwater sediment, a methylotrophic methanogen able to grow on dimethyl sulfide and methanethiol.	a newly isolated methanogen, strain dms1(t), is the first obligately anaerobic archaeon which was directly enriched and isolated from a freshwater sediment in defined minimal medium containing dimethyl sulfide (dms) as the sole carbon and energy source. the use of a chemostat with a continuous dms-containing gas stream as a method of enrichment, followed by cultivation in deep agar tubes, resulted in a pure culture. since the only substrates utilized by strain dms1(t) are methanol, methylamines, ...	1999	10427061
glycine betaine transport in the obligate halophilic archaeon methanohalophilus portucalensis.	transport of the osmoprotectant glycine betaine was investigated using the glycine betaine-synthesizing microbe methanohalophilus portucalensis (strain fdf1), since solute uptake for this class of obligate halophilic methanogenic archaea has not been examined. betaine uptake followed a michaelis-menten relationship, with an observed k(t) of 23 microm and a v(max) of 8 nmol per min per mg of protein. the transport system was highly specific for betaine: choline, proline, and dimethylglycine did n ...	2000	10940053
methanohalophilus zhilinae sp. nov., an alkaliphilic, halophilic, methylotrophic methanogen.	methanohalophilus zhilinae, a new alkaliphilic, halophilic, methylotrophic species of methanogenic bacteria, is described. strain wen5t (t = type strain) from bosa lake of the wadi el natrun in egypt was designated the type strain and was further characterized. this strain was nonmotile, able to catabolize dimethylsulfide, and able to grow in medium with a methyl group-containing substrate (such as methanol or trimethylamine) as the sole organic compound added. sulfide (21 mm) inhibited cultu ...	1988	11540079
beta-glutamate as a substrate for glutamine synthetase.	the conversion of beta-glutamate to beta-glutamine by archaeal and bacterial glutamine synthetase (gs) enzymes has been examined. the gs from methanohalophilus portucalensis (which was partially purified) is capable of catalyzing the amidation of this substrate with a rate sevenfold less than the rate obtained with alpha-glutamate. recombinant gs from the archaea methanococcus jannaschii and archaeoglobus fulgidus were considerably more selective for alpha-glutamate than beta-glutamate as a subs ...	2001	11571143
composition, variation, and dynamics of major osmotic solutes in methanohalophilus strain fdf1.	methanohalophilus strain fdf1, a member of the halophilic genus of methanogens, can grow over a range of external nacl concentrations from 1.2 to 2.9 m and utilize methanol, trimethylamine, and dimethyl sulfide as substrates for methanogenesis. it produces the osmolytes glycine betaine, beta-glutamine, and n-acetyl-beta-lysine with increasing external nacl, but the relative ratio of these zwitterions depends primarily on the methanogenic substrate and less on the external osmolarity. when the ce ...	1992	16348748
influence of ph on ammonia accumulation and toxicity in halophilic, methylotrophic methanogens.	we studied the effects of ph and ammonia concentration on the growth of three methanogens. these three halophilic, methylotrophic methanogens, methanolobus bombayensis, methanolobus taylorii, and methanohalophilus zhilinaeae, grew at environmental ph ranges that overlapped with each other and spanned the ph range from 7.0 to 9.5. during growth they had reversed membrane ph gradients ((delta)ph) at all ph values tested. the (delta)ph was in the range of -0.4 to -0.9 ph units, with the cytosol bei ...	1996	16535465
effects of osmolyte precursors on the distribution of compatible solutes in methanohalophilus portucalensis.	the halophilic methanogen methanohalophilus portucalensis synthesizes three distinct zwitterions, (beta)-glutamine, n(sup(epsilon))-acetyl-(beta)-lysine (na(beta)lys), and glycine betaine, as osmolytes when it is grown at high concentrations of external nacl. the selective distribution of these three species was determined by growing cells in the presence of osmolyte biosynthetic precursors. glycine betaine is formed by the stepwise methylation of glycine. exogenous glycine (10 mm) and sarcosine ...	1997	16535715
effects of substrate and potassium on the betaine-synthesizing enzyme glycine sarcosine dimethylglycine n-methyltransferase from a halophilic methanoarchaeon methanohalophilus portucalensis.	methanohalophilus portucalensis fdf1 can synthesize the compatible solute betaine de novo through the methylation of glycine, sarcosine and dimethylglycine with the methyl group from s-adenosylmethionine. after separation by deae-sephacel ion chromatography using a kcl step gradient, glycine, sarcosine and dimethylglycine methytransfer (gsdmt) activities were detected in a single peak. the estimated molecular weight of gsdmt was 240 kda and 2-d gel analysis indicated it was separated into four s ...	2006	17098399
salinity constraints on subsurface archaeal diversity and methanogenesis in sedimentary rock rich in organic matter.	the diversity of microorganisms active within sedimentary rocks provides important controls on the geochemistry of many subsurface environments. in particular, biodegradation of organic matter in sedimentary rocks contributes to the biogeochemical cycling of carbon and other elements and strongly impacts the recovery and quality of fossil fuel resources. in this study, archaeal diversity was investigated along a salinity gradient spanning 8 to 3,490 mm cl(-) in a subsurface shale rich in ch(4) d ...	2007	17468287
analysis of the aaa+ chaperone clpb gene and stress-response expression in the halophilic methanogenic archaeon methanohalophilus portucalensis.	clpb is a member of the protein-disaggregating chaperone machinery belonging to the aaa+ superfamily. this paper describes a new clpb gene from the halophilic methanoarchaeon methanohalophilus portucalensis, which has not been reported previously in archaea. the partial sequence of clpb was identified from the investigation of the salt-stress response of meh. portucalensis by differential-display rt-pcr (ddrt-pcr). furthermore, the complete clpb sequence (2610 nt) and its upstream genes encoding ...	2007	17660421
characterization of osmolyte betaine synthesizing sarcosine dimethylglycine n-methyltransferase from methanohalophilus portucalensis.	to overcome the extracellular salt stress, methanohalophilus portucalensis fdf1(t) synthesizes the compatible solute betaine through the methylation of glycine, sarcosine, and n,n-dimethylglycine. s-adenosylmethionine (adomet) is the methyl donor. the enzyme sarcosine dimethylglycine n-methyltransferase (sdmt) of m. portucalensis, that catalyzes the formation of n,n-dimethylglycine and glycine betaine, has been purified and characterized. sdmt, a monomer of 33 kda with a pi at 5.03, has a narrow ...	2009	19693490
differentially expressed genes after hyper- and hypo-salt stress in the halophilic archaeon methanohalophilus portucalensis.	methanohalophilus portucalensis fdf1 can grow over a range of external nacl concentrations, from 1.2 to 2.9 mol/l. differential gene expression in response to long-term hyper-salt stress (3.1 mol/l of nacl) and hypo-salt stress (0.9 mol/l of nacl) were compared by differential display rt-pcr. fourteen differentially expressed genes responding to long-term hyper- or hypo-salt stress were detected, cloned, and sequenced. several of the differentially expressed genes were related to the unique ener ...	2010	20453896
the genome sequence of methanohalophilus mahii slp(t) reveals differences in the energy metabolism among members of the methanosarcinaceae inhabiting freshwater and saline environments.	methanohalophilus mahii is the type species of the genus methanohalophilus, which currently comprises three distinct species with validly published names. mhp. mahii represents moderately halophilic methanogenic archaea with a strictly methylotrophic metabolism. the type strain slp(t) was isolated from hypersaline sediments collected from the southern arm of great salt lake, utah. here we describe the features of this organism, together with the complete genome sequence and annotation. the 2,012 ...	2010	21234345
Characterization and regulation of the osmolyte betaine synthesizing enzymes GSMT and SDMT from halophilic methanogen Methanohalophilus portucalensis.	The halophilic methanoarchaeon Methanohalophilus portucalensis can synthesize the osmolyte betaine de novo in response to extracellular salt stress. Betaine is generated by the stepwise methylation of glycine to form sarcosine, N, N-dimethylglycine and betaine by using S-adenosyl-L-methionine (AdoMet) as the methyl donor. The complete gene cluster of Mpgsmt-sdmt was cloned from Southern hybridization and heterologous expressed in E. coli respectively. The recombinant MpGSMT and MpSDMT both retai ...	2011	21949863