A Conserved Streptococcal Virulence Regulator Controls the Expression of a Distinct Class of M-Like Proteins
A Conserved Streptococcal Virulence Regulator Controls the Expression of a Distinct Class of M-Like Proteins
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保守的链球菌毒力调节因子控制一类独特的 M 样蛋白的表达
DOI：
10.1128/mbio.02500-19
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发表时间：
2019-09-01
期刊：
影响因子：
6.4
通讯作者：
Waldor, Matthew K.
中科院分区：
文献类型：
--
作者：
D'Gama, Jonathan D.;Ma, Zhe;Waldor, Matthew K.
M蛋白是人类病原体A群链球菌的表面锚定毒力因子。本文中，我们在马链球菌亚种动物流行病（SEZ）中鉴定出一种m样蛋白SzM及其阳性调节因子SezV， SEZ是家畜（包括马和猪）的重要病原体群。在所有SEZ和马链球菌亚种马链球菌和M18 A群链球菌的基因组中均发现了SzM和SezV同源物，但在其他链球菌中未发现。缺乏sezV或szM的突变SEZ菌株在小鼠感染模型中被高度减毒。总之，我们的研究结果表明，与sezv相关的调节因子和与之相关的m样蛋白的SzM家族定义了一个新的毒力链球菌亚群。马链球菌（Streptococcus equi zooepidemic， SEZ）是一种C群链球菌，是马、猪等经济动物的重要致病菌。在这里，我们发现许多SEZ分离物与识别聚n -乙酰氨基葡萄糖（PNAG）的单克隆抗体结合，PNAG是一种在多种微生物上发现的表面胶囊状结构的聚合物。采用基于荧光激活细胞分选的转座子插入测序（Tn-seq）筛选，结合全基因组测序，寻找PNAG生物合成基因。令人惊讶的是，编码m样蛋白szM和相邻转录因子sezV的基因突变使菌株PNAG呈阴性。szM的表达需要SezV，转录组分析表明SezV有一个小的调控子。在小鼠感染模型中，sezV或szM失活突变的SEZ菌株被高度减毒。比较基因组分析显示，sezV和szM同源物存在于数据库中的所有SEZ、马链球菌亚种马（SEE）和M18 A群链球菌（GAS）基因组中，但不存在于其他链球菌中。PNAG抗体与多种SEZ、SEE和M18 GAS菌株结合。免疫化学研究表明，虽然无法分离到完整的低聚糖取代基，但SzM蛋白可能被pnag样低聚糖修饰。总之，我们的研究结果表明，szM和sezV基因座定义了一种强毒链球菌亚型，PNAG抗体可能在由携带szM样蛋白的链球菌引起的动物和人类疾病中具有治疗应用。重要性M蛋白是人类病原体A群链球菌的表面锚定毒力因子。本文中，我们在马链球菌亚种动物流行病（SEZ）中鉴定出一种m样蛋白SzM及其阳性调节因子SezV， SEZ是家畜（包括马和猪）的重要病原体群。在所有SEZ和马链球菌亚种马链球菌和M18 A群链球菌的基因组中均发现了SzM和SezV同源物，但在其他链球菌中未发现。缺乏sezV或szM的突变SEZ菌株在小鼠感染模型中被高度减毒。总之，我们的研究结果表明，与sezv相关的调节因子和与之相关的m样蛋白的SzM家族定义了一个新的毒力链球菌亚群。
M proteins are surface-anchored virulence factors in group A streptococci, human pathogens. Here, we identified an M-like protein, SzM, and its positive regulator, SezV, in Streptococcus equi subspecies zooepidemicus (SEZ), an important group of pathogens for domesticated animals, including horses and pigs. SzM and SezV homologues were found in the genomes of all SEZ and S. equi subspecies equi and M18 group A streptococcal strains analyzed but not in other streptococci. Mutant SEZ strains lacking either sezV or szM were highly attenuated in a mouse model of infection. Collectively, our findings suggest that SezV-related regulators and the linked SzM family of M-like proteins define a new subset of virulent streptococci. ABSTRACT Streptococcus equi subspecies zooepidemicus (SEZ) are group C streptococci that are important pathogens of economically valuable animals such as horses and pigs. Here, we found that many SEZ isolates bind to a monoclonal antibody that recognizes poly-N-acetylglucosamine (PNAG), a polymer that is found as a surface capsule-like structure on diverse microbes. A fluorescence-activated cell sorting-based transposon insertion sequencing (Tn-seq) screen, coupled with whole-genome sequencing, was used to search for genes for PNAG biosynthesis. Surprisingly, mutations in a gene encoding an M-like protein, szM, and the adjacent transcription factor, designated sezV, rendered strains PNAG negative. SezV was required for szM expression and transcriptome analysis showed that SezV has a small regulon. SEZ strains with inactivating mutations in either sezV or szM were highly attenuated in a mouse model of infection. Comparative genomic analyses revealed that linked sezV and szM homologues are present in all SEZ, S. equi subspecies equi (SEE), and M18 group A streptococcal (GAS) genomes in the database, but not in other streptococci. The antibody to PNAG bound to a wide range of SEZ, SEE, and M18 GAS strains. Immunochemical studies suggest that the SzM protein may be decorated with a PNAG-like oligosaccharide although an intact oligosaccharide substituent could not be isolated. Collectively, our findings suggest that the szM and sezV loci define a subtype of virulent streptococci and that an antibody to PNAG may have therapeutic applications in animal and human diseases caused by streptococci bearing SzM-like proteins. IMPORTANCE M proteins are surface-anchored virulence factors in group A streptococci, human pathogens. Here, we identified an M-like protein, SzM, and its positive regulator, SezV, in Streptococcus equi subspecies zooepidemicus (SEZ), an important group of pathogens for domesticated animals, including horses and pigs. SzM and SezV homologues were found in the genomes of all SEZ and S. equi subspecies equi and M18 group A streptococcal strains analyzed but not in other streptococci. Mutant SEZ strains lacking either sezV or szM were highly attenuated in a mouse model of infection. Collectively, our findings suggest that SezV-related regulators and the linked SzM family of M-like proteins define a new subset of virulent streptococci.