Molecular features governing the stability and specificity of functional complex formation by Mycobacterium tuberculosis CFP-10/ESAT-6 family proteins
Molecular features governing the stability and specificity of functional complex formation by Mycobacterium tuberculosis CFP-10/ESAT-6 family proteins
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DOI：
10.1074/jbc.m800123200
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发表时间：
2008-06-20
影响因子：
4.8
通讯作者：
Carr, Mark D.
中科院分区：
文献类型：
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作者：
Lightbody, Kirsty L.;Ilghari, Dariush;Carr, Mark D.
结核分枝杆菌复合体CFP-10/ESAT-6家族蛋白在结核病发病机制中发挥重要但定义不清的作用。在这篇文章中，我们报告的CFP 10/ESAT-6家庭的几个成员的详细光谱研究的结果。这项工作表明，CFP-10/ESAT-6相关蛋白Rv 0287和Rv 0288形成紧密的1：1复合物，其主要是螺旋结构，预计与CFP-10和ESAT-6形成的复合物非常相似。此外，发现Rv0287.Rv0288复合物对化学和温度诱导的变性都比CFP-10.ESAT-6显著更稳定。该方法证明，Rv0287.Rv0288和CFP-10.ESAT-6复合物在低pH（4.5）下均不稳定，表明即使在低pH环境中，例如成熟吞噬体，Rv0287.Rv0288和CFP-10.ESAT-6无疑都作为复合物而不是单独的蛋白质起作用。CFP-10.ESAT-6复合物的结构分析和M.对结核CFP-10/ESAT-6家族蛋白的研究表明，参与螺旋之间分子内接触的残基在CFP-10/ ESAT-6家族中是保守的，但不参与主要分子间接触的残基。该分析确定了CFP-10/ ESAT-6家族蛋白之间复合物形成的特异性和稳定性的分子基础，并表明在发病机制中具有关键作用的功能复合物的形成将限于基因组伴侣或非常密切相关的家族成员，如Rv 0287/Rv 0288和Rv 3019 c/Rv 3020 c。
The Mycobacterium tuberculosis complex CFP-10/ESAT-6 family proteins play essential but poorly defined roles in tuberculosis pathogenesis. In this article we report the results of detailed spectroscopic studies of several members of the CFP10/ESAT-6 family. This work shows that the CFP-10/ESAT-6 related proteins, Rv0287 and Rv0288, form a tight 1:1 complex, which is predominantly helical in structure and is predicted to closely resemble the complex formed by CFP-10 and ESAT-6. In addition, the Rv0287.Rv0288 complex was found to be significantly more stable to both chemical and temperature induced denaturation than CFP-10.ESAT-6. This approach demonstrated that neither Rv0287.Rv0288 nor the CFP-10.ESAT-6 complexes are destabilized at low pH (4.5), indicating that even in low pH environments, such as the mature phagosome, both Rv0287.Rv0288 and CFP-10.ESAT-6 undoubtedly function as complexes rather than individual proteins. Analysis of the structure of the CFP-10.ESAT-6 complex and optimized amino acid sequence alignments of M. tuberculosis CFP-10/ESAT-6 family proteins revealed that residues involved in the intramolecular contacts between helices are conserved across the CFP-10/ ESAT-6 family, but not those involved in primarily intermolecular contacts. This analysis identified the molecular basis for the specificity and stability of complex formation between CFP-10/ ESAT-6 family proteins, and indicates that the formation of functional complexes with key roles in pathogenesis will be limited to genome partners, or very closely related family members, such as Rv0287/Rv0288 and Rv3019c/Rv3020c.