期刊名称:Proceedings of the National Academy of Sciences
印刷版ISSN:0027-8424
电子版ISSN:1091-6490
出版年度:1989
卷号:86
期号:22
页码:8842-8846
DOI:10.1073/pnas.86.22.8842
语种:English
出版社:The National Academy of Sciences of the United States of America
摘要:Resistance to penicillin in clinical isolates of Streptococcus pneumoniae has occurred by the development of altered penicillin-binding proteins (PBPs) that have greatly decreased affinity for the antibiotic. We have investigated the origins of penicillin-resistant strains by comparing the sequences of the transpeptidase domain of PBP2B from 6 penicillin-sensitive and 14 penicillin-resistant strains. In addition we have sequenced part of the amylomaltase gene from 2 of the sensitive and 6 of the resistant strains. The sequences of the amylomaltase gene of all of the strains and of the PBP2B gene of the penicillin-sensitive strain show that S. pneumoniae is genetically very uniform. In contrast the PBP2B genes of the penicillin-resistant strains show approximately equal to 14% sequence divergence from those of the penicillin-sensitive strains and the development of penicillin resistance has involved the replacement, presumably by transformation, of the original PBP2B gene by a homologous gene from an unknown source. This genetic event has occurred on at least two occasions, involving different sources, to produce the two classes of altered PBP2B genes found in penicillin-resistant strains of S. pneumoniae. There is considerable variation among the PBP2B genes of the resistant strains that may have arisen by secondary transformation events accompanied by mismatch repair subsequent to their original introductions into S. pneumoniae.