Hyperphosphorylation of the Group A Streptococcal Control of Virulence Regulator Increases Promoter Occupancy Specifically at Virulence Factor-Encoding Genes.
Hyperphosphorylation of the Group A Streptococcal Control of Virulence Regulator Increases Promoter Occupancy Specifically at Virulence Factor-Encoding Genes.
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DOI：
10.1128/jb.00118-23
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发表时间：
2023-06-27
影响因子：
3.2
通讯作者：
中科院分区：
文献类型：
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毒力双组分基因调控系统（CovRS）的调控在许多重要的链球菌致病过程中起着关键作用。在emm 1 A组链球菌（GAS）中，CovR直接结合许多GAS毒力因子编码基因的启动子。CovS磷酸酶活性的消除增加CovR磷酸化（CovR~P）水平并消除GAS毒力。鉴于CovRS功能的emm类型特异性多样性，在这项研究中，我们使用染色质免疫沉淀测序（ChIP-seq）来确定野生型emm 3菌株MGAS 10870（中等CovR~P）及其CovS磷酸酶阴性衍生物10870-CovS-T284 A（高CovR~P）中的总体CovR DNA占有率。在野生型emm 3菌株中，89%的先前确定的emm 1 CovR结合位点存在于emm 3基因组中也被富集;此外，我们确定了独特的CovR结合，主要与移动的遗传元件中的基因和菌株间染色体差异的其他位点结合。CovS磷酸酶活性的消除特异性地增加了CovR在广泛的CovR抑制的毒力因子编码基因的启动子处的占有率，包括编码关键GAS调节剂Mga和M蛋白的那些。然而，有限数量的启动子在低CovR~P水平下增强富集。使用高与低CovR~P水平富集的序列进行差异基序搜索，发现两种不同的结合模式。在高CovR~P下，确定了与CovR结合为二聚体一致的假白链AT丰富的共有序列（WTWTTATAAWAAAAWNATDA）。相反，在低CovR~P特异性富集的序列含有孤立的ATTARA基序，表明与单体的相互作用。这些数据扩展了对全球CovR DNA占有率的理解，超出了emm 1 GAS，并为先前关于CovS磷酸酶消除诱导的毒性降低的观察结果提供了一种机制。鉴于CovR在革兰氏阳性菌发病机制中的关键作用，CovR是OmpR/PhoB转录调节因子家族中最重要的成员之一。在此，我们将最近在emm 1中进行的GAS CovR全局结合分析扩展到非emm 1菌株，考虑到GAS CovRS功能中已知的emm类型间异质性，这一点很重要。我们的数据提供了对covRS功能变化的机制性理解，除了表明磷酸化和非磷酸化covR亚型在特定covR结合位点的差异靶向外，还表明了emm类型和covS磷酸酶阴性菌株的严重毒力低下之间的差异。这些发现推进了关于关键细菌毒力调节因子如何影响发病机制的知识，并增加了对非磷酸化OmpR/PhoB家族成员功能的日益认识。
The control of virulence two-component gene regulatory system (CovRS) is critical to the pathogenesis of many medically important streptococci. In emm1 group A streptococci (GAS), CovR directly binds the promoters of numerous GAS virulence factor-encoding genes. Elimination of CovS phosphatase activity increases CovR phosphorylation (CovR~P) levels and abrogates GAS virulence. Given the emm type-specific diversity of CovRS function, in this study we used chromatin immunoprecipitation sequencing (ChIP-seq) to define global CovR DNA occupancy in the wild-type emm3 strain MGAS10870 (medium CovR~P) and its CovS phosphatase-negative derivative 10870-CovS-T284A (high CovR~P). In the wild-type emm3 strain, 89% of the previously identified emm1 CovR binding sites present in the emm3 genome were also enriched; additionally, we ascertained unique CovR binding, primarily to genes in mobile genetic elements and other sites of interstrain chromosomal differences. Elimination of CovS phosphatase activity specifically increased CovR occupancy at the promoters of a broad array of CovR repressed virulence factor-encoding genes, including those encoding the key GAS regulator Mga and M protein. However, a limited number of promoters had augmented enrichment at low CovR~P levels. Differential motif searches using sequences enriched at high versus low CovR~P levels revealed two distinct binding patterns. At high CovR~P, a pseudopalindromic AT-rich consensus sequence (WTWTTATAAWAAAAWNATDA) consistent with CovR binding as a dimer was determined. Conversely, sequences specifically enriched at low CovR~P contained isolated ATTARA motifs suggesting an interaction with a monomer. These data extend understanding of global CovR DNA occupancy beyond emm1 GAS and provide a mechanism for previous observations regarding hypovirulence induced by CovS phosphatase abrogation. IMPORTANCE Given its key role in pathogenesis of Gram-positive bacteria, CovR is one of the most important members of the OmpR/PhoB family of transcriptional regulators. Herein we extend recent GAS CovR global binding analyses done in emm1 to a non-emm1 strain, which is important considering the known inter-emm-type heterogeneity in GAS CovRS function. Our data provide mechanistic understanding for variation in CovRS function between emm types and the profound hypovirulence of CovS phosphatase-negative strains in addition to indicating differential targeting by phosphorylated and nonphosphorylated CovR isoforms at specific CovR binding sites. These findings advance knowledge regarding how a key bacterial virulence regulator impacts pathogenesis and add to the growing appreciation of the function of nonphosphorylated OmpR/PhoB family members.
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