title: Growth- and substrate-dependent transcription of formate dehydrogenase and hydrogenase coding genes in Syntrophobacter fumaroxidans and Methanospirillum hungatei.
abstract: Transcription of genes coding for formate dehydrogenases (fdh genes) and hydrogenases (hyd genes) in Syntrophobacter fumaroxidans and Methanospirillum hungatei was studied following growth under different conditions. Under all conditions tested, all fdh and hyd genes were transcribed. However, transcription levels of the individual genes varied depending on the substrate and growth conditions. Our results strongly suggest that in syntrophically grown S. fumaroxidans cells, the [FeFe]-hydrogenase (encoded by Sfum_844-46), FDH1 (Sfum_2703-06) and Hox (Sfum_2713-16) may confurcate electrons from NADH and ferredoxin to protons and carbon dioxide to produce hydrogen and formate, respectively. Based on bioinformatic analysis, a membrane-integrated energy-converting [NiFe]-hydrogenase (Mhun_1741-46) of M. hungatei might be involved in the energy-dependent reduction of CO(2) to formylmethanofuran. The best candidates for F(420)-dependent N(5),N(10)-methyl-H(4) MPT and N(5),N(10),-methylene-H(4)MPT reduction are the cytoplasmic [NiFe]-hydrogenase and FDH1. 16S rRNA ratios indicate that in one of the triplicate co-cultures of S. fumaroxidans and M. hungatei, less energy was available for S. fumaroxidans. This led to enhanced transcription of genes coding for the Rnf-complex (Sfum_2694-99) and of several fdh and hyd genes. The Rnf-complex probably reoxidized NADH with ferredoxin reduction, followed by ferredoxin oxidation by the induced formate dehydrogenases and hydrogenases.
authors.affiliation: Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen, The Netherlands.
authors.forename: Petra
authors.initials: P
authors.lastname: Worm
authors.affiliation: Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen, The Netherlands.
authors.forename: Alfons J M
authors.initials: AJM
authors.lastname: Stams
authors.affiliation: Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen, The Netherlands.
authors.forename: Xu
authors.initials: X
authors.lastname: Cheng
authors.affiliation: Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen, The Netherlands.
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Plugge
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D020564:Deltaproteobacteria / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D005288:Ferredoxins / Q000378:metabolism; D005560:Formate Dehydrogenases / Q000096:biosynthesis* / Q000235:genetics; D005561:Formates / Q000378:metabolism; D005663:Furans / Q000378:metabolism; D015870:Gene Expression; D006859:Hydrogen / Q000378:metabolism; D006864:Hydrogenase / Q000235:genetics*; D053858:Metabolic Networks and Pathways; D019639:Methanospirillum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D008954:Models, Biological; D009097:Multienzyme Complexes / Q000235:genetics*; D009243:NAD / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D005288:Ferredoxins; D005561:Formates; D005663:Furans; D009097:Multienzyme Complexes; D009243:NAD; C030544:formic acid; D002245:Carbon Dioxide; D006859:Hydrogen; C050842:formylmethanofuran; D006864:Hydrogenase; D005560:Formate Dehydrogenases; C054017:formate hydrogenlyase