Structural Variabilities in β-Lactamase (blaA) of Different Biovars of Yersinia enterocolitica: Implications for β-Lactam Antibiotic and β-Lactamase Inhibitor Susceptibilities.
Yersiniosis caused by Yersinia enterocolitica has been reported from all continents. The bacterial species is divided into more than fifty serovars and six biovars viz. 1A, 1B, 2, 3, 4 and 5 which differ in geographical distribution, ecological niches and pathogenicity. Most Y.enterocolitica strains harbor chromosomal genes for two β-lactamases, blaA an Ambler class A penicillinase and blaB an Ambler class C inducible cephalosporinase. In the present study, susceptibility to b-lactam antibiotics and β-lactamase inhibitor was studied for Y. enterocolitica strains of biovars 1A, 1B, 2 and 4. We observed that β-lactamases were expressed differentially among strains of different biovars. To understand the molecular mechanisms underlying such differential expression, the sequences of genes and promoters of blaA were compared. Also, the variants of blaA present in different biovars were modeled and docked with amoxicillin and clavulanic acid. The mRNA secondary structures of blaA variants were also predicted in-silico. Our findings indicated that neither variations in the promoter regions, nor the secondary structures of mRNA contributed to higher/lower expression of blaA in different biovars. Analysis of H-bonding residues of blaA variants with amoxicillin and clavulanic acid revealed that if amino acid residues of a β-lactamase interacting with amoxicillin and the clavulanic acid were similar, clavulanic acid was effective in engaging the enzyme, accounting for a significant reduction in MIC of amoxicillin-clavulanate. This finding might aid in designing better β-lactamase inhibitors with improved efficiencies in future.
Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi, India.
Neelja
N
Singhal
Department of Biophysics, University of Delhi South Campus, Benito Juarez Road, New Delhi, India.
Abhishikha
A
Srivastava
Department of Biophysics, University of Delhi South Campus, Benito Juarez Road, New Delhi, India.
Manish
M
Kumar
Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi, India.
Jugsharan Singh
JS
Virdi
D019943:Amino Acid Substitution; D000658:Amoxicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics*; D019818:Clavulanic Acid / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial; D006860:Hydrogen Bonding / Q000187:drug effects; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012333:RNA, Messenger / Q000737:chemistry; D015008:Yersinia enterocolitica / Q000145:classification / Q000187:drug effects* / Q000201:enzymology*; D065093:beta-Lactamase Inhibitors / Q000494:pharmacology*; D047090:beta-Lactams / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D065093:beta-Lactamase Inhibitors; D047090:beta-Lactams; C074160:BlaA protein, Bacteria; D019818:Clavulanic Acid; D000658:Amoxicillin