Synthesis of gamma-glutamylcysteine as a major low-molecular-weight thiol in lactic acid bacteria Leuconostoc spp.
Some members of lactic acid bacteria are known to synthesize glutathione (GSH) or to import it from growth medium, whereas others are not. Analysis of the genome sequences of several Leuconostoc spp. indicate the presence of the gene gshA that encodes gamma-glutamylcysteine synthetase, but not the gene gshB encoding glutathione synthetase. We report here that, in cells of Leuconostoc kimchii and Leuconostoc mesenteroides, gamma-glutamylcysteine (gamma-GC) is present in large amount, whereas GSH is not detectable. The level of gamma-GC was higher at the stationary phase than at the exponential phase. Expression of the gshA gene in Leuconostoc spp. analyzed by S1 mapping showed the increased mRNA level upon hydrogen peroxide treatment. From high-resolution S1 mapping, the transcriptional start site was mapped and the putative promoter elements were suggested. This work suggests that gamma-GC has a significant role in Leuconostoc spp. as the major low-molecular-weight thiol.
Kim
Eun-Kyoung
EK
School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul 151-742, Republic of Korea.
Cha
Chang-Jun
CJ
Cho
Yong-Joon
YJ
Cho
Yoo-Bok
YB
Roe
Jung-Hye
JH
D001426:Bacterial Proteins / Q000235:genetics*; D004151:Dipeptides / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D015870:Gene Expression; D005798:Genes, Bacterial; D005721:Glutamate-Cysteine Ligase / Q000235:genetics*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D019344:Lactic Acid / Q000378:metabolism; D007934:Leuconostoc / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D008970:Molecular Weight; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D024363:Transcription Initiation Site
D001426:Bacterial Proteins; D004151:Dipeptides; D012333:RNA, Messenger; D013438:Sulfhydryl Compounds; D019344:Lactic Acid; D006861:Hydrogen Peroxide; D015719:Single-Strand Specific DNA and RNA Endonucleases; D005721:Glutamate-Cysteine Ligase; C017341:gamma-glutamylcysteine