Abstract
Yersinia enterocolitica is an enteric bacterium which can cause severe gastroenteritis. Beta-lactams are the most widely used antibiotics against Y. enterocolitica. Y. enterocolitica produces two chromosomal β-lactamases, BlaA and BlaB. BlaB is an Ambler Class C inducible broad spectrum cephlaosporinase which showed differential enzyme activity in different biotypes of Y. enterocolitica. The expression of blaB is mainly regulated by ampR- the transcriptional regulator and, ampD - which helps in peptidoglycan recycling. The aim of this study was to identify and characterize genetic determinants underlying differential enzyme activity of BlaB in Y. enterocolitica biotypes 1 A, IB, 2 and 4. Thus, ampR, blaB and ampD were PCR-amplified and modeled in silico. The intercistronic region containing promoters of ampR and blaB was also investigated. Our results indicated that blaB was more inducible in biotypes 2 and 4, than in biotypes 1 A and 1B. Superimposition of in silico modeled proteins suggested that variations in amino acid sequences of AmpR, BlaB and AmpD were not responsible for hyper-production of BlaB in biotypes 2 and 4. Analysis of promoter regions of ampR and blaB revealed variations at −30, −37 and −58 positions from blaB transcription start site. Studies on relative expression levels of blaB in different biotypes by qRT-PCR indicated that nucleotide variations at these positions might contribute to a higher enzyme activity of BlaB in biotypes 2 and 4. However, this is a preliminary study and further studies including more strains of each biotype are required to strengthen our findings. Nevertheless, to the best of our knowledge, this is the first study which has investigated the genetic determinants underlying differential inducible production of BlaB in different biotypes of Y. enterocolitica.
Highlights
Infections due to Yersinia enterocolitica have been reported from almost all the countries around the world
As reported for the AmpC enzymes present in other members of the family Enterobacteriaceae expression of “AmpC-type” enzymes in Y. enterocolitica is mainly regulated by ampR which is a transcriptional regulator of ampC and, ampD which participates in recycling of peptidoglycan[8]
multiple sequence alignment (MSA) of the intercistronic region containing the promoter sequences of blaB and ampR of strains of different biotypes revealed that the −10 and −35 regions of ampR and blaB promoters were similar in all biotypes
Summary
Infections due to Yersinia enterocolitica have been reported from almost all the countries around the world. As reported for the AmpC enzymes present in other members of the family Enterobacteriaceae expression of “AmpC-type” enzymes in Y. enterocolitica is mainly regulated by ampR which is a transcriptional regulator of ampC and, ampD which participates in recycling of peptidoglycan[8]. The un-recycled muropeptides bind to ampR and inhibits its normal activity This results in ampC de-repression i.e activation of ampC expression[10,11]. The aim of the present study was to identify and characterize genetic determinants underlying differential inducible expression of blaB in Y. enterocolitica strains of biotypes 1 A, IB, 2 and 4. To the best of our knowledge, this is the first study which has investigated the genetic determinants underlying differential inducible expression of blaB in Y. enterocolitica strains of different biotypes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
