The Two-Component Signal Transduction System CopRS of Corynebacterium glutamicum Is Required for Adaptation to Copper-Excess Stress

Abstract

Copper is an essential cofactor for many enzymes but at high concentrations it is toxic for the cell. Copper ion concentrations ≥50 µM inhibited growth of Corynebacterium glutamicum. The transcriptional response to 20 µM Cu2+ was studied using DNA microarrays and revealed 20 genes that showed a ≥ 3-fold increased mRNA level, including cg3281-cg3289. Several genes in this genomic region code for proteins presumably involved in the adaption to copper-induced stress, e. g. a multicopper oxidase (CopO) and a copper-transport ATPase (CopB). In addition, this region includes the copRS genes (previously named cgtRS9) which encode a two-component signal transduction system composed of the histidine kinase CopS and the response regulator CopR. Deletion of the copRS genes increased the sensitivity of C. glutamicum towards copper ions, but not to other heavy metal ions. Using comparative transcriptome analysis of the ΔcopRS mutant and the wild type in combination with electrophoretic mobility shift assays and reporter gene studies the CopR regulon and the DNA-binding motif of CopR were identified. Evidence was obtained that CopR binds only to the intergenic region between cg3285 (copR) and cg3286 in the genome of C. glutamicum and activates expression of the divergently oriented gene clusters cg3285-cg3281 and cg3286-cg3289. Altogether, our data suggest that CopRS is the key regulatory system in C. glutamicum for the extracytoplasmic sensing of elevated copper ion concentrations and for induction of a set of genes capable of diminishing copper stress.

3-Amino-4-hydroxybenzoic acid production from sweet sorghum juice by recombinant Corynebacterium glutamicum

“…2C). To our knowledge, the presence of a fermentation inhibitor in sweet sorghum juice has not been reported, although heavy metal stress induced by high concentrations of copper, but not manganese or zinc, has been reported in C. glutamicum (Schelder et al, 2011). Consistent with this finding, 3,4-AHBA production from sweet sorghum juice was reduced by 28% in CGX II medium supplemented with trace metals including copper, iron, manganese, nickel, and zinc (Fig.…”

Copper-responsive gene regulation in bacteria

“…Upon exposure to copper, C. glutamicum strongly induces expression of the divergently transcribed copR-copS-cg3283-cg3282-copB and cg3286-copO-cg3288-cg3289 operons, which encode the twocomponent system CopRS, the copper-ATPase CopB, and the extracellular MCO CopO (Schelder et al, 2011). In contrast to its E. coli counterpart, CusR, which binds a dyad-symmetrical sequence, CopR binds the direct repeat sequence TGAAGATTT-N 2 -TGAAGATTT within the copR-cg3286 intergenic region, which is the only CopR target in the entire C. glutamicum genome.…”

“…Although MCOs function in the periplasm, there is no apparent preference for CusRS systems, which sense periplasmic copper concentrations, over CueR sensors, which respond to the cytoplasmic copper status. It is worth noting that the copper-inducible MCO in the Gram-positive bacterium C. glutamicum contains a cysteine residue, thought to serve as a lipid anchor, immediately downstream of the signal peptide cleavage site (Palmer & Berks, 2012;Schelder et al, 2011).…”

The two-component system ChrSA is crucial for haem tolerance and interferes with HrrSA in haem-dependent gene regulation in Corynebacterium glutamicum

“…In total, 13 TCSs are encoded in the C. glutamicum genome (Kocan et al, 2006), several of which have been studied in more detail Bott & Brocker, 2012;Schaaf & Bott, 2007;Schelder et al, 2011). In a recent study, we demonstrated that the TCS HrrSA exhibits a central function in the control of haem homeostasis and haem utilization in C. glutamicum.…”