# Global Proteomic Analysis Reveals the Roles of MicX in Biofilm Formation and Quorum Sensing in Vibrio alginolyticus

## TL;DR

This study explores how the sRNA MicX affects biofilm formation and communication in Vibrio alginolyticus, a seafood-borne pathogen, using proteomic analysis.

## Contribution

The study reveals the regulatory role of MicX in biofilm and quorum sensing through a novel proteomic analysis in Vibrio alginolyticus.

## Key findings

- The ΔmicX mutant showed reduced biofilm formation and exopolysaccharide synthesis.
- Proteomic analysis identified 900 differentially expressed proteins, with significant changes in quorum sensing and biofilm-related proteins.
- MicX influences type VI secretion and MSHA proteins, which are crucial for virulence and adhesion.

## Abstract

Vibrio alginolyticus is a foodborne pathogen commonly found in seafood and freshwater products, causing human illness through the consumption of tainted seafood. Small non-coding RNAs (sRNAs) take effect on the stability and translation of their target mRNAs by base-pairing, thereby quickly altering bacterial physiology and pathogenicity at the post-transcriptional level. This work constructed a label-free in-frame deletion mutant and a complement strain of micX, a cell-density-associated sRNA in V. alginolyticus. The ΔmicX mutant exhibited reduced growth and a reduction in the synthesis of exopolysaccharides, biofilm, and alkaline serine protease. A TMT-based quantitative proteomic analysis comparing ΔmicX with the wild-type strain identified 900 differentially expressed proteins, comprising 376 that were upregulated and 524 that were downregulated. The upregulated proteins are primarily associated with porin activity, transmembrane signaling receptor function, and the two-component system. The downregulated proteins are mainly engaged in processes including biofilm formation, cellular communication, and transmembrane transport activity. Of note, the expression levels of proteins involved in the type VI secretion system, exopolysaccharide synthesis, mannose-sensitive hemagglutinin type IV pili (MSHA), and biofilm formation were significantly reduced in the absence of micX. Furthermore, the expression levels of proteins associated with quorum sensing (particularly LuxR and AphA) changed significantly in the ΔmicX vs. WT comparison. These findings strengthened comprehension of the novel sRNA regulatory network and established a theoretical foundation for additional investigations into the virulence of V. alginolyticus.