title: Computational analysis of cysteine and methionine metabolism and its regulation in dairy starter and related bacteria.
abstract: Sulfuric volatile compounds derived from cysteine and methionine provide many dairy products with a characteristic odor and taste. To better understand and control the environmental dependencies of sulfuric volatile compound formation by the dairy starter bacteria, we have used the available genome sequence and experimental information to systematically evaluate the presence of the key enzymes and to reconstruct the general modes of transcription regulation for the corresponding genes. The genomic organization of the key genes is suggestive of a subdivision of the reaction network into five modules, where we observed distinct differences in the modular composition between the families Lactobacillaceae, Enterococcaceae, and Leuconostocaceae, on the one hand, and the family Streptococcaceae, on the other. These differences are mirrored by the way in which transcription regulation of the genes is structured in these families. In the Lactobacillaceae, Enterococcaceae, and Leuconostocaceae, the main shared mode of transcription regulation is methionine (Met) T-box-mediated regulation. In addition, the gene metK, encoding S-adenosylmethionine (SAM) synthetase, is controlled via the S(MK) box (SAM). The S(MK) box is also found upstream of metK in species of the family Streptococcaceae. However, the transcription control of the other modules is mediated via three different LysR-family regulators, MetR/MtaR (methionine), CmbR (O-acetyl[homo]serine), and HomR (O-acetylhomoserine). Redefinition of the associated DNA-binding motifs helped to identify/disentangle the related regulons, which appeared to perfectly match the proposed subdivision of the reaction network.
authors.affiliation: FrieslandCampina Research, Deventer, The Netherlands.
authors.forename: Mengjin
authors.initials: M
authors.lastname: Liu
authors.forename: Celine
authors.initials: C
authors.lastname: Prakash
authors.forename: Arjen
authors.initials: A
authors.lastname: Nauta
authors.forename: Roland J
authors.initials: RJ
authors.lastname: Siezen
authors.forename: Christof
authors.initials: C
authors.lastname: Francke
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D019295:Computational Biology / Q000379:methods; D003545:Cysteine / Q000378:metabolism*; D003612:Dairying; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D056546:Lactobacillales / Q000145:classification / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D008715:Methionine / Q000378:metabolism*; D008716:Methionine Adenosyltransferase / Q000235:genetics / Q000378:metabolism; D012436:S-Adenosylmethionine / Q000378:metabolism; D013289:Streptococcaceae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D014157:Transcription Factors; D012436:S-Adenosylmethionine; D008715:Methionine; D008716:Methionine Adenosyltransferase; D003545:Cysteine