New genetic element carrying the erythromycin resistance determinant erm (TR) in Streptococcus pneumoniae
New genetic element carrying the erythromycin resistance determinant erm (TR) in Streptococcus pneumoniae
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DOI：
10.1128/aac.01081-07
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发表时间：
2008-02-01
影响因子：
4.9
通讯作者：
Pantostil, Annalisa
中科院分区：
文献类型：
--
作者：
Carnilli, Rornina;Del Grosso, Maria;Pantostil, Annalisa
在临床分离的1株肺炎链球菌中发现了一种常见的大环内酯类抗生素耐药决定簇-β（A）亚类β（TR）。pneumoniae分离意大利（AP 200）。在该分离物中，发现包含在大小约56 kb的遗传元件中，该遗传元件似乎不是接合的，但可以通过转化转移。对一个约10 kb的含TR的DNA片段进行测序，鉴定出12个开放阅读框（ORF）。结果表明，在TR 1（TR）的上游存在TOR家族的调节蛋白和ABC型外排泵的两个组分，在TR 2（TR）的下游存在与壮观霉素磷酸转移酶、转座酶和松弛酶同源的ORF。由于S.当携带β-内酰胺酶（TR）的化脓性链球菌MGAS 10750变得可用时，在AP 200和MGAS 10750中的含β-内酰胺酶（TR）的遗传元件之间进行比较。MGAS 10750中的12个ORF中有10个与AP 200的侧翼区（TR）相同。使用针对MGAS 10750序列设计的引物进行的PCR作图证实，AP 200携带与MGAS 10750相似的遗传元件。在AP 200中，该基因被插入到与S. pneumoniae R6，编码I型限制性修饰系统。AP 200和MGAS 10750中插入位点之间的同源性由8个保守核苷酸组成，其中3个是重复的，可能代表靶位点重复。携带转座子（TR）的遗传元件的结构显示转座子/原噬菌体残余嵌合体的特征。在AP 200中，这个基因元件被命名为Tn 1806。
erm(A) subclass erm(TR), a common macrolide resistance determinant in Streptococcus pyogenes but quite rare in Streptococcus pneumoniae, was found in a clinical S. pneumoniae isolate (AP200) from Italy. In this isolate, erm(TR) was found included in a genetic element approximately 56 kb in size that did not appear to be conjugative but could be transferred by transformation. An erm (TR)-containing DNA fragment of approximately 10 kb was sequenced and 12 open reading frames (ORFs) were identified. Upstream of erm(TR), a regulatory protein of the TOR family and the two components of an efflux pump of the ABC type were found. Downstream of erm(TR), there were ORFs homologous to a spectinomycin phosphotransferase, transposases, and a relaxase. Since the genomic sequence of S. pyogenes MGAS10750 carrying erm(TR) became available, comparison between the erm (TR) -containing genetic elements in AP200 and in MGAS10750 was performed. The region flanking erm(TR) in MGAS10750 showed identity with AP200 for 10 ORFs out of 12. PCR mapping using primers designed on the sequence of MGAS10750 confirmed that AP200 carries a genetic element similar to that of MGAS10750. In AP200 the genetic element was inserted inside an ORF homologous to spr0790 of S. pneumoniae R6, coding for a type I restriction modification system. Homologies between the insertion sites in AP200 and MGAS10750 consisted of eight conserved nucleotides, of which three were duplicated, likely representing target site duplication. The structure of the erm (TR)-carrying genetic element shows characteristics of a transposon/prophage remnant chimera. In AP200 this genetic element was designated Tn1806.