The CrdRS two‐component system in Helicobacter pylori responds to nitrosative stress

• Published in: Molecular microbiology Vol. 97; no. 6; pp. 1128 - 1141
• Main Authors: Hung, Chiu‐Lien, Cheng, Hsin‐Hung, Hsieh, Wan‐Chen, Tsai, Zing Tsung‐Yeh, Tsai, Huai‐Kuang, Chu, Chia‐Han, Hsieh, Wen‐Ping, Chen, Yi‐Fan, Tsou, Yu, Lai, Chih‐Ho, Wang, Wen‐Ching
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.09.2015
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Base Sequence; Copper - metabolism; DNA-Binding Proteins - metabolism; Gene expression; Gene Expression Profiling; Gene Knockout Techniques; Gram-negative bacteria; Helicobacter pylori - genetics; Helicobacter pylori - metabolism; Molecular Sequence Data; Nitric oxide; Nitric Oxide - metabolism; Promoter Regions, Genetic; Proteins; Stress, Physiological
• DOI: 10.1111/mmi.13089
• ISSN: 0950-382X

Summary Helicobacter pylori inhabits the gastric mucosa where it senses and responds to various stresses via a two‐component systems (TCSs) that enable its persistent colonization. The aim of this study was to investigate whether any of the three paired TCSs (ArsRS, FleRS and CrdRS) in H. pylori respond to nitrosative stress. The results showed that the expression of crdS was significantly increased upon exposure to nitric oxide (NO). crdS‐knockout (ΔcrdS) and crdR/crdS‐knockout (ΔcrdRS) H. pylori, but not arsS‐knockout (ΔarsS) or fleS‐knockout (ΔfleS) H. pylori, showed a significant loss of viability upon exposure to NO compared with wild‐type strain. Knockin crdS (ΔcrdS‐in) significantly restored viability in the presence of NO. Global transcriptional profiling analysis of wild‐type and ΔcrdS H. pylori in the presence or absence of NO showed that 101 genes were differentially expressed, including copper resistance determinant A (crdA), transport, binding and envelope proteins. The CrdR binding motifs were investigated by competitive electrophoretic mobility shift assay, which revealed that the two AC‐rich regions in the crdA promoter region are required for binding. These results demonstrate that CrdR–crdA interaction enables H. pylori to survive under nitrosative stress. Helicobacter pylori successfully responds and adapts to various stresses from gastric environment via its three‐pair two‐component systems (TCSs). This report shows that a unique TCS, CrdRS, functions as a sensor for nitrosative stress. Nitrosative challenge differentially upregulates the expression of resistance determinant A (crdA). Further, CrdR binds to the proximal promoter region of crdA that consists of a two AC‐rich region. These findings demonstrate that CrdR‐crdA interaction enables H. pylori to survive under nitrosative stress.