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Structural Variabilities in β-Lactamase (blaA) of Different Biovars of Yersinia enterocolitica: Implications for β-Lactam Antibiotic and β-Lactamase Inhibitor Susceptibilities.

Singhal N, Srivastava A, Kumar M, Virdi JS - PLoS ONE (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi, India.

ABSTRACT
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.

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Related in: MedlinePlus

Multiple sequence alignment of the promoter region ofblaA ofY.enterocolitica biovar IA, 1B, 2 and4 strains.The transcription start site (TSS), -10 and -30 regions are shown. The -10region was conserved but variations were observed in the -30 region.
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pone.0123564.g004: Multiple sequence alignment of the promoter region ofblaA ofY.enterocolitica biovar IA, 1B, 2 and4 strains.The transcription start site (TSS), -10 and -30 regions are shown. The -10region was conserved but variations were observed in the -30 region.

Mentions: Mutations and insertions in the promoters of β-lactamase genes have also beenreported to be associated with differential expression of β-lactamases [5]. Thus, the nucleotidesequences of promoters of blaA of strains of different biovars wereanalyzed. The sequence of the -10 box of all biovars, TATAAT was identical in allbiovars and closely resembled the canonical E.colipromoter implying that the rate of transcription of blaA inY.enterocolitica was quite high. It is wellknown that the sequences in the -35 and -10 regions or sometimes the spacer betweenthese regions affect the transcription efficiency of bacterial promoters. Two singlenucleotide substitutions were observed in the -35 region and three in the ribosomalbinding region in biovars 1A and 1B (Fig 4). These substitutions might exert lesser influence on enzymeexpression, as mutations in the -10 region rather than in -35 regions have beenreported to be associated with drug resistance in several members of the familyEnterobacteriaceae such as Klebsiella oxytoca[16]. However, this mightbe proved by comparison of blaA expression levels in strains of different biovars byquantitative PCR (QPCR). Moreover, these nucleotide substitutions might have notbeen responsible for higher expression of blaAx which was observed in biovar 1Astrain because the same promoter sequence was present in blaAy which showedconsiderably lower MIC for AMX and AMC.


Structural Variabilities in β-Lactamase (blaA) of Different Biovars of Yersinia enterocolitica: Implications for β-Lactam Antibiotic and β-Lactamase Inhibitor Susceptibilities.

Singhal N, Srivastava A, Kumar M, Virdi JS - PLoS ONE (2015)

Multiple sequence alignment of the promoter region ofblaA ofY.enterocolitica biovar IA, 1B, 2 and4 strains.The transcription start site (TSS), -10 and -30 regions are shown. The -10region was conserved but variations were observed in the -30 region.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4414059&req=5

pone.0123564.g004: Multiple sequence alignment of the promoter region ofblaA ofY.enterocolitica biovar IA, 1B, 2 and4 strains.The transcription start site (TSS), -10 and -30 regions are shown. The -10region was conserved but variations were observed in the -30 region.
Mentions: Mutations and insertions in the promoters of β-lactamase genes have also beenreported to be associated with differential expression of β-lactamases [5]. Thus, the nucleotidesequences of promoters of blaA of strains of different biovars wereanalyzed. The sequence of the -10 box of all biovars, TATAAT was identical in allbiovars and closely resembled the canonical E.colipromoter implying that the rate of transcription of blaA inY.enterocolitica was quite high. It is wellknown that the sequences in the -35 and -10 regions or sometimes the spacer betweenthese regions affect the transcription efficiency of bacterial promoters. Two singlenucleotide substitutions were observed in the -35 region and three in the ribosomalbinding region in biovars 1A and 1B (Fig 4). These substitutions might exert lesser influence on enzymeexpression, as mutations in the -10 region rather than in -35 regions have beenreported to be associated with drug resistance in several members of the familyEnterobacteriaceae such as Klebsiella oxytoca[16]. However, this mightbe proved by comparison of blaA expression levels in strains of different biovars byquantitative PCR (QPCR). Moreover, these nucleotide substitutions might have notbeen responsible for higher expression of blaAx which was observed in biovar 1Astrain because the same promoter sequence was present in blaAy which showedconsiderably lower MIC for AMX and AMC.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi, India.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus