Opposing regulation of Gig2 by RecA and GlrK controls redox-linked desiccation tolerance in Cronobacter sakazakii

Abstract

Cronobacter sakazakii is a desiccation-tolerant foodborne pathogen that poses a serious threat to neonatal health through contamination of powdered infant formula. Despite its clinical relevance and exceptional persistence in dry environments, the molecular basis of its desiccation tolerance remains poorly defined. Here, we systematically investigated the genetic and physiological determinants of C. sakazakii survival under desiccation stress. A functional screen of gene knockout strains revealed intricate relationships between surface hydrophilicity and desiccation tolerance, suggesting the involvement of alternative protective pathways. Integrative proteomic analysis identified the DUF1479 family oxidase Gig2 as a previously unrecognized factor critical for survival during desiccation and oxidative stress. Loss of Gig2 results in a significant reduction in desiccation tolerance, as indicated by a 2.2-log CFU decrease after 21 days of desiccation, without impacting surface hydrophilicity or growth under normal conditions. Structure-based molecular docking further revealed that phloretin, a natural polyphenol, binds Gig2 with high affinity and significantly reduces bacterial survival under dry conditions. These findings reveal a hydrophilicity-independent mechanism of desiccation tolerance in C. sakazakii and highlight Gig2 as a promising molecular target for controlling its persistence in low-moisture foods.