This domain family is found in VraX proteins from Staphylococcus aureus. The vraX gene belongs to the vra operon together with the vraA gene encoding for a long chain fatty acid-CoA ligase, which is up-regulated in the VISA (vancomycin-intermediate S. aureus) [1]. The gene product, a 55-amino acids protein,is upregulated in the stress response to cell wall-active antibiotics and other surface-interactive molecules. VraX harbors a putative phosphorylation site, and could therefore be involved in regulatory processes within the cell. However, no exact function has been demonstrated [2].

1: Quantitative proteomic view associated with resistance to clinically important antibiotics in Gram-positive bacteria: a systematic review. Lee CR, Lee JH, Park KS, Jeong BC, Lee SH; Front Microbiol. 2015;6:828. PMID:26322035

2: Impact of space flight on bacterial virulence and antibiotic susceptibility. Taylor PW; Infect Drug Resist. 2015;8:249-262. PMID:26251622