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Paralogous metabolism: S ‐alkyl‐cysteine degradation in Bacillus subtilis
Author(s) -
Chan CheMan,
Danchin Antoine,
Marlière Philippe,
Sekowska Agnieszka
Publication year - 2014
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12210
Subject(s) - bacillus subtilis , cysteine , biology , acetylation , biochemistry , operon , metabolism , gene , sulfur , metabolite , bacteria , enzyme , genetics , mutant , chemistry , organic chemistry
Summary Metabolism is prone to produce analogs of essential building blocks in the cell (here named paralogous metabolism). The variants result from lack of absolute accuracy in enzyme‐templated reactions as well as from molecular aging. If variants were left to accumulate, the earth would be covered by chemical waste. The way bacteria cope with this situation is essentially unexplored. To gain a comprehensive understanding of B acillus subtilis sulphur paralogous metabolism, we used expression profiling with DNA arrays to investigate the changes in gene expression in the presence of S ‐methyl‐cysteine ( SMeC ) and its close analog, methionine, as sole sulphur source. Altogether, more than 200 genes whose relative strength of induction was significantly different depending on the sulphur source used were identified. This allowed us to pinpoint operon ytmItcy JKLMNytmO _ytn IJ _rbf K _ytn LM as controlling the pathway cycling SMeC directly to cysteine, without requiring sulphur oxygenation. Combining genetic and physiological experiments, we deciphered the corresponding pathway that begins with protection of the metabolite by acetylation. Oxygenation of the methyl group then follows, and after deprotection (deacetylation), N ‐formyl cysteine is produced. This molecule is deformylated by the second deformylase present in B . subtilis DefB , yielding cysteine. This pathway appears to be present in plant‐associated microbes.