Genetic organisation of the M protein region in human isolates of group C and G streptococci:: two types of multigene regulator-like (mgrC) regions
Genetic organisation of the M protein region in human isolates of group C and G streptococci:: two types of multigene regulator-like (mgrC) regions
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DOI：
10.1007/pl00008665
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发表时间：
2000-01-01
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影响因子：
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通讯作者：
Schmidt, KH
中科院分区：
文献类型：
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作者：
Geyer, A;Schmidt, KH
除了属于兰斯菲尔德A组（化脓性链球菌，GAS）的β-溶血性链球菌外，C组（GCS）和G组（GGS）链球菌（S.停乳亚种equisimilis）被认为是化脓性咽炎、伤口感染以及最近链球菌中毒性休克样综合征爆发的病原体。关于GCS和GCS的emm基因所在的基因组区域的组织知之甚少。我们已经调查了基因组序列侧翼的emm基因在GCS通过测序获得的反向PCR的相邻片段。我们对GCS菌株25287和H46 A的序列数据揭示了emm区域中的两种类型的排列，这与GAS中已知类型的mga调节子显著不同。我们将该基因组片段命名为mgrC（C组链球菌中的多基因调节子样片段）。在属于第一种mgrC型的菌株（原型菌株25287）中，emm基因上游侧接mgc，该基因与GAS的mga基因具有61%的同一性。推导的蛋白质序列的系统发育分析表明，Mgc相关的Mga蛋白的各种类型的GAS，但形成一个独特的集群。在emm的下游，mgrC序列区域与rel邻接。该基因编码一种蛋白质，该蛋白质在对氨基酸剥夺的严格调节反应期间在鸟苷3 '，5'二焦磷酸（ppGpp）的合成和降解中起作用。在第二种mgrC类型（原型菌株H46 A）中，基因mgc和emm如类型1中那样排列。但是在emm和rel之间以相反的方向插入额外的ORF（orf）。该ORF显示与cpdB的序列同源性，cpdB存在于各种微生物中并编码2 '，3'环核苷酸2 '-磷酸二酯酶。PCR分析表明，这两种mgrC排列也存在于GGS中。我们的序列和PCR数据进一步表明，GCS和GGS中的两种类型的mgrC区域通过rel与最近在菌株H46 A中表征的链激酶区域连接。GAS中存在于mga调节子3'端的编码C5 a肽酶的基因，在本文研究的GCS和GGS菌株中鉴定的mgrC区中未发现。
In addition to beta-haemolytic streptococci belonging to Lancefield group A (Streptococcus pyogenes, GAS), human isolates of group C (GCS) and group G (GGS) streptococci (S. dysgalactiae subsp. equisimilis:) have been implicated as causative agents in outbreaks of purulent pharyngitis, of wound infections and recently also of streptococcal toxic shock-like syndrome. Very little is known about the organisation of the genomic region in which the emm gene of GCS and GCS is located. We have investigated the genome sequences flanking the emm gene in GCS by sequencing neighbouring fragments obtained by inverse PCR. Our sequence data for GCS strains 25287 and H46A revealed two types of arrangement in the emm region, which differ significantly from the known types of mga regulon in GAS. We named this segment of the genome mgrC (for multigene regulon-like segment in group C streptococci). In strains belonging to the first mgrC type (prototype strain 25287) the emm gene is flanked upstream by mgc, a gene that is 61% identical to the mga gene of GAS. A phylogenetic analysis of the deduced protein sequences showed that Mgc is related to Mga proteins of various types of GAS but forms a distinct cluster. Downstream of emm, the mgrC sequence region is bordered by rel. This gene encodes a protein that functions in the synthesis and degradation of guanosine 3',5' bipyrophosphate (ppGpp) during the stringent regulatory response to amino acid deprivation. In the second mgrC type (prototype strain H46A), the genes mgc and emm are arranged as in type 1. But an additional ORF (orf) is inserted in opposite orientation between emm and rel. This orf shows sequence homology to cpdB, which is present in various microorganisms and encodes 2',3' cyclo-nucleotide 2'-phosphodiesterase. PCR analysis showed that these two mgrC arrangements also exist in GGS. Our sequence and PCR data further showed that both types of mgrC region in GCS and GGS are linked via rel to the streptokinase region characterised recently in strain H46A. A gene encoding C5a peptidase, which is present at the 3' end of the mga regulon in GAS, was not found in the mgrC region identified in the GCS and GGS strains investigated here.