马链球菌兽疫亚种中马链菌素A基因及其抗性基因的流行率与获得情况
Prevalence and acquisition of the genes for zoocin A and zoocin A resistance in Streptococcus equi subsp. zooepidemicus.
作者信息
Gargis Amy S, O'Rourke Anna-Lee D, Sloan Gary L, Simmonds Robin S
机构信息
Department of Biological Sciences, The University of Alabama, Box 870334, Tuscaloosa, AL 35487-0334, USA.
出版信息
J Mol Evol. 2009 May;68(5):498-505. doi: 10.1007/s00239-009-9221-x. Epub 2009 Apr 9.
Zoocin A is a streptococcolytic enzyme produced by Streptococcus equi subsp. zooepidemicus strain 4881. The zoocin A gene (zooA) and the gene specifying resistance to zoocin A (zif) are adjacent on the chromosome and are divergently transcribed. Twenty-four S. equi subsp. zooepidemicus strains were analyzed to determine the genetic difference among three previously characterized as zoocin A producers (strains 4881, 9g, and 9h) and the 21 nonproducers. LT-PCR and Southern hybridization studies revealed that none of the nonproducer strains possessed zooA or zif. RAPD and PFGE showed that the 24 strains were a genetically diverse population with eight RAPD profiles. S. equi subsp. zooepidemicus strains 9g and 9h appeared to be genetically identical to each other but quite different from strain 4881. Sequences derived from 4881 and 9g showed that zooA and zif were integrated into the chromosome adjacent to the gene flaR. A comparison of these sequences with the genome sequences of S. equi subsp. zooepidemicus strains H70 and MGCS10565 and S. equi subsp. equi strain 4047 suggests that flaR flanks a region of genome plasticity in this species.
马链菌素A是由马链球菌兽疫亚种4881菌株产生的一种链球菌溶解酶。马链菌素A基因（zooA）和赋予对马链菌素A抗性的基因（zif）在染色体上相邻，且转录方向相反。分析了24株马链球菌兽疫亚种菌株，以确定先前鉴定为马链菌素A产生菌的3株菌株（4881、9g和9h菌株）与21株非产生菌之间的遗传差异。长模板PCR（LT-PCR）和Southern杂交研究表明，非产生菌菌株均不具有zooA或zif。随机扩增多态性DNA（RAPD）和脉冲场凝胶电泳（PFGE）显示，这24株菌株是一个具有8种RAPD图谱的遗传多样性群体。马链球菌兽疫亚种9g和9h菌株似乎彼此基因相同，但与4881菌株有很大差异。来自4881和9g的序列表明，zooA和zif整合到与flaR基因相邻的染色体中。将这些序列与马链球菌兽疫亚种H70和MGCS10565菌株以及马链球菌马亚种4047菌株的基因组序列进行比较，表明flaR位于该物种基因组可塑性区域的侧翼。
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