Species-Specific Gene Expansion and Expressional Regulation of the Serine Protease Gene Family in Staphylococcus aureus from chronic wounds

Abstract

Background Chronic wounds caused by pressure ulcers, diabetes foot ulcers, lower extremity arteriovenous ulcers, etc., not only increase the pain and mortality of patients, but also increase the social medical burden. The formation of bacterial biofilm is an important reason for the difficulty in healing chronic wounds. Staphylococcus aureus biofilm is an important pathogenic factor leading to the spread of infection in chronic wounds.Results Through comparative genomic analysis of S. aureus isolated from wounds and environmental samples, it was found that the unique genes of the wound isolate were enriched in the serine type peptidase activity, as well as metabolic pathways such as quorum sensing, signal transduction, and two component system. According to the analysis of the serine protease family of S. aureus, it was found that most of S. aureus strains isolated from the wound contains six serine protease-like proteins (SplA, SplB, SplC, SplD, SplE, SplF). The Staphylococcus phase UPMK1 may horizontally transfer the six serine protease-like protein genes to S. aureus in wounds and spread within the species. Through the transcriptome analysis of wild strain JE2 and its gltS knockout strains, it was found that the expression of serine protease genes (S1C, SspA, SplA and SplF) was significantly up-regulated when gltS mutant strains were cultured for 48 h in biofilm formation, which may play an important role in biofilm formation and pathogenicity.Conclusions Staphylococcus phase expand the genome of S. aureus in wounds. The spl serine protease gene of the S. aureus strain from the wound was obtained through horizontal gene transfer. The significant upregulation of gene expression of serine proteases (S1C, SspA, SplA, and SplF) is closely related to the formation of wound biofilm of S. aureus.