MULTIPLE ANTIBIOTIC RESISTANCE ACTIVATOR (MarA) OF THE FAMILY ENTEROBACTERIACEAE: STRUCTURE AND CONSERVATION IN Salmonella enterica SUBSP. enterica SEROVAR TYPHIMURIUM

Abstract

MarA (the multiple antibiotic resistance activator) is a regulatory protein that plays a significant role in multidrug resistance in bacteria and archaea where cellular mechanisms such as DNA and protein synthesis are inhibited during dormancy and subsequently cells evade a sudden antibiotic stress. MarAs (125–127 residues) of species selected from ten genera of the family Enterobacteriaceae were selected for analyses. MarA consists of seven α-helices where about 81 % of the residues in helices are conserved. The helices and folds in MarA of Salmonella enterica serovar typhimurium can be further divided into two structurally similar and interconnected subdomains, each containing a HTH DNA-binding motif. The recognition helices, H3 and H6 of the motifs are fully conserved, which are inserted into the adjacent major groove segments of DNA. The sequences show high similarity (83.4–100 %) with MarA of E. coli K-12 with fully resolved three-dimensional structure at 2.3 Å.