DegS regulates the aerobic metabolism of Vibrio cholerae via the ArcA-isocitrate dehydrogenase pathway for growth and intestinal colonization.

Aerobic respiration is the key driver of Vibrio cholerae proliferation and infection. Our previous transcriptome results suggested that degS knockout downregulates a few genes involved in NADH and ATP synthesis in the aerobic respiratory pathway. In this study, non-targeted metabolomics results showed that the differential metabolites affected by degS knockout were associated with aerobic respiration. Further results suggested that the key products of aerobic respiration, NADH and ATP, were reduced upon degS deletion and were not dependent on the classical σ^E pathway. The two-component system response factor aerobic respiration control A (ArcA) is involved in regulating NADH and ATP levels. qRT-PCR demonstrated that DegS negatively regulates the transcription of the arcA gene, which negatively regulates the expression of isocitrate dehydrogenase (ICDH), a key rate-limiting enzyme of the tricarboxylic acid cycle. NADH and ATP levels were partially restored with the knockout of the arcA gene in the ΔdegS strain, while levels were partially restored with overexpression of ICDH in the ΔdegS strain. In a growth experiment, compared to the ΔdegS strain, the growth rates of ΔdegSΔarcA and ΔdegS-overexpressed icdh strains (ΔdegS+icdh) were partially restored during the logarithmic growth period. Colonization of the intestines of suckling mice showed a significant reduction in the colonizing ability of the ΔdegS strain, similar colonizing ability of the ΔdegS::degS strain and the wild-type strain, and a partial recovery of the colonizing ability of the ΔdegS+icdh strain. Overall, these findings suggest that the DegS protease regulates the expression of ICDH through ArcA, thereby affecting the NADH and ATP levels of V. cholerae and its growth and intestinal colonization ability.