DecR is a regulator with an important role in cysteine detoxification. The absence of decR increases the inhibitory effect on bacterial growth caused by cysteine .
The presence of cysteine improves the interaction between DecR and the promoter region of the operon yhaOM, thereby causing activation .
DecR (YbaO) may have a role in Rob-mediated regulation . In a Salmonella enterica cutR mutant, E. coli ybaO restored cysteine-responsive regulation of the CdsH cysteine desulfhydrase .
decR is a member of the Rob regulon .
Based on transcript profiling with a cyuR mutant and overpression of cyuR under anaerobic cysteine growth conditions, 37 genes showed at least a 5-fold change in expression, with increased expression of 20 genes and diminished expression of 17 genes .
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Some of the induced genes included the following: the two most upregulated genes, cyuP
; proteins involved in aromatic amino acid metabolism: two genes of the tyrA-aroF
, and aroL
; and several genes for proteins involved in carbohydrate metabolism, lacI
, two genes of the srlA
operon, and all the genes of the uidABC
operons. Six of the repressed genes degrade glucarate and galacturate: gudP
and the adjacent garPLRK
operons. Nine of the downregulated genes are in the maltose regulon: malEFG
, and malS 
toxification of c