The ArcAB two-component system is associated with the susceptibility of Aggregatibacter actinomycetemcomitans to superoxide and hydrogen peroxide
Year: 2025
Type: dissertation
Abstract: Aggregatibacter actinomycetemcomitans is a Gram-negative facultative anaerobe and is associated with periodontal disease. This bacterium is exposed to environmental stresses, such as osmotic pressure, temperature shifts, pH shifts, and antimicrobial substances, including reactive oxygen species (ROS), in the human oral cavity. The bacterial two-component system ArcAB modulates gene expression in response to environmental changes, primarily by sensing oxygen pressure in several pathogens belonging to the γ-proteobacteria. It is also known to provide adaptation to ROS stress; however, its function in A. actinomycetemcomitans remains unclear. In this study, we found that the expression of sod, which encodes superoxide dismutase, was increased in the inactivated mutant of arcA, which encodes a response regulator. The mutant exhibited reduced susceptibility to superoxide and hydrogen peroxide (H2O2). Additionally, this strain showed reduced susceptibility to H2O2 from Streptococcus sanguinis and increased survival in macrophages. Since ArcB is the cognate histidine kinase of ArcA, the inactivated mutant of arcB was analyzed for its phenotypes. The arcB mutant exhibited reduced susceptibility to superoxide and H2O2. Compared to wild type, the phosphorylation level of ArcA in the arcB mutant was decreased. These results suggest that the ArcA response regulator receives phosphate groups from ArcB histidine kinase and negatively regulates the expression of sod, thereby affecting bacterial survival in response to ROS produced by oral commensals and host immune cells.
Source: Kagoshima University Repository
Authors: RATMAN FARID MOHAMMAD, 145069
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7112491552
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