The prevalence of unusual intramolecular thioester cross-link on the surface proteins of Enterococci

• Main Authors: Su-yin, Kan, Nabilah Huda, Abdul Halim
• Format: Article
• Language: English
• Published: 2017
• Subjects: Q Science (General); QH426 Genetics
• Online Access: http://eprints.unisza.edu.my/5804/1/FH02-FSK-18-13124.pdf; http://eprints.unisza.edu.my/5804/

The emergence of nosocomial infections caused by multi-drug resistant enterococci is becoming a cause for concern. According to the 2015 National Surveillance of Antibiotic Resistance (NSAR) report by the Ministry of Health Malaysia, Enterococcus faecium was found to be resistant to a variety of antibiotics especially to vancomycin which recorded an increased resistant rate. Recent studies showed that many clinically significant Grampositive human pathogens possess a unique covalent intramolecular thioester bond on at least one of their surface 24dhesion proteins which may serve as potential therapeutic targets, an alternative to antibiotics. Sequence search based on the protein query of thioester-containing domain (TED) of Streptococcus pyogenes were performed using the Basic Local Alignment Search Tool (BLAST) against non-redundant protein sequences (nr) and UniProt Knowledgebase (UniProtKB) databases. The protein BLAST followed by multiple sequence alignment revealed that a total of 54 strains of E. faecium and 75 strains of E. faecalis were predicted to contain a thioester bond on their surface protein, whereby the critical cysteine and glutamine residues were found to be perfectly conserved. These predicted TEDs showed low sequence homology (about 35 % similarity) to known streptococcal TED and many of which functions are unknown. However, the high prevalence of TEDs across enterococcal strains is astonishing. Therefore, the biochemical function of thioester bond in these proteins contributing to enterococcal pathogenicity needs to be further assessed experimentally, which may serve as a new drug target or diagnostic tool for enterococcal infections.