Alterations in penicillin-binding protein 2B from penicillin-resistant wild-type strains of Streptococcus pneumoniae.
AUTOR(ES)
Smith, A M
RESUMO
The 1.5-kb transpeptidase-encoding region (TER) of penicillin-binding protein (PBP) 2B was amplified and sequenced from 18 penicillin-resistant isolates of Streptococcus pneumoniae, with each isolate representing a different DNA fingerprint profile of the TER. PBP 2B TERs from penicillin-resistant isolates revealed extensive sequence divergence from the penicillin-susceptible R6 strain, differing by up to 170 nucleotide substitutions and resulting in up to 38 alterations in the amino acid sequence of the protein. All penicillin-resistant isolates showed sequence divergence within a +/- 300-bp area at the center of the PBP 2B TER. Although a number of amino acid substitutions were found within this central area of PBP 2B, only two substitutions were common to all resistant isolates, namely, Thr-252 replacement by Ala and Glu-282 replacement by Gly. These two substitutions appear to be essentially associated with a decreased affinity of PBP 2B for penicillin. A second block of divergent nucleotide sequence was prominent amongst isolates with high levels of resistance. This was a +/- 100-bp area of the TER around nucleotide 1300 and included the substitution of Gly for Asp-431, which was the only amino acid substitution within this area that was common to all isolates. These data may assist in the definition of the structural changes in the penicillin-binding site of PBP 2B associated with penicillin resistance in S. pneumoniae.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=162643Documentos Relacionados
- Penicillin-resistant viridans streptococci have obtained altered penicillin-binding protein genes from penicillin-resistant strains of Streptococcus pneumoniae.
- Alterations in kinetic properties of penicillin-binding proteins of penicillin-resistant Streptococcus pneumoniae.
- Directly repeated insertion of 9-nucleotide sequence detected in penicillin-binding protein 2B gene of penicillin-resistant Streptococcus pneumoniae.
- Horizontal transfer of penicillin-binding protein genes in penicillin-resistant clinical isolates of Streptococcus pneumoniae.
- Penicillin-Binding Protein 1A, 2B, and 2X Alterations in Canadian Isolates of Penicillin-Resistant Streptococcus pneumoniae