The chemoreceptor McpA mediates aerotaxis and redox taxis in Salmonella Typhimurium

McpA, the chemosensory zinc-binding receptor in Salmonella Typhimurium, mediates attraction to O2 and to biologically relevant HOCl, H2O2, and organic hydroperoxides.

• Why it matters: Oxidant and oxygen chemistry shapes bacterial survival, but how CZB-containing receptors sense specific ROS and whether they encode a distinct sensory logic in environmental bacteria is unclear.
• What they did: Using time-resolved video microscopy, the study directly visualized swimming and taxis behaviors and tested responses to O2 plus HOCl, H2O2, and organic hydroperoxides, alongside zinc availability and Zn2+ forms.
• The result: McpA-dependent taxis is controlled by Zn2+ availability, and exogenous OZn2 and ROS promote insoluble zinc precipitates that may create Zn2+ gradients sensed via the CZB domain.

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