whcA gene plays a negative role in oxidative stress response of Corynebacterium glutamicum

• Published in: FEMS microbiology letters 2009, Vol.290 (1), p.32-38
• Main Authors: Choi, Woon-Woo, Park, Soo-Dong, Lee, Seok-Myung, Kim, Hyung-Bai, Kim, Younhee, Lee, Heung-Shick
• Format: Article
• Language: English
• Subjects: Alcohol dehydrogenase; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Clonal deletion; Corynebacterium glutamicum; Corynebacterium glutamicum - enzymology; Corynebacterium glutamicum - genetics; Corynebacterium glutamicum - metabolism; Corynebacterium glutamicum - physiology; Culture Media; Electrophoresis; Electrophoresis, Gel, Two-Dimensional; Fundamental and applied biological sciences. Psychology; Gel electrophoresis; Gene Deletion; Gene expression; Gene Expression Regulation, Bacterial; Genetics; Growth conditions; Heat-Shock Response; Homology; Hydrogen peroxide; Menadione; Microbiology; Molecular and cellular biology; Molecular genetics; Mutants; NADH; NADH oxidase; Nicotinamide adenine dinucleotide; Oxidants; Oxidative stress; Oxidative Stress - physiology; Oxidizing agents; Polyacrylamide; Proteins; Quinones; Reductase; Reductases; sigH; Sigma Factor - genetics; Sigma Factor - metabolism; stress; Stress response; Thioredoxin; Thioredoxin-Disulfide Reductase - genetics; Thioredoxin-Disulfide Reductase - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Up-Regulation; whcA
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1111/j.1574-6968.2008.01398.x

In this study, we analyzed the whcA gene from Corynebacterium glutamicum, which codes for a homologue of the WhiB-family of proteins. Deletion of the gene did not affect the growth of the mutant cells, indicating that the whcA gene was not essential under ordinary growth conditions. However, cells overexpressing the protein not only showed retarded growth as compared with the wild-type or the ΔwhcA mutant cells but also showed increased sensitivity to a variety of oxidants, such as diamide, menadione, and hydrogen peroxide. Thioredoxin reductase activity was repressed in the whcA-overexpressing cells, whereas its activity in the ΔwhcA mutant strain was derepressed regardless of the presence of oxidative stress. The whcA gene was constitutively expressed throughout the growth phase and its expression level was not affected by oxidative stress. A set of proteins under the control of whcA were identified by two-dimensional polyacrylamide gel electrophoresis and they were annotated as NADH oxidase, alcohol dehydrogenase, quinone reductase, and cysteine desulfurase. The corresponding genes encoding the identified proteins were not transcribed in ΔsigH mutant cells. Collectively, these data suggest that the whcA gene of C. glutamicum plays a negative role in the sigH-mediated stress response pathway.