G148-GA3: a streptococcal virulence module with atypical thermodynamics of folding optimally binds human serum albumin at physiological temperatures.
G148-GA3: a streptococcal virulence module with atypical thermodynamics of folding optimally binds human serum albumin at physiological temperatures.
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G148-GA3：具有非典型折叠热力学的链球菌毒力模块，可在生理温度下最佳地结合人血清白蛋白。
DOI：
10.1016/j.bbapap.2005.10.005
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Bryan,PhilipN
中科院分区：
文献类型：
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作者：
Rozak,DavidA;Orban,John;Bryan,PhilipN
链球菌蛋白G菌株148的第三个白蛋白结合域（G148-GA3）属于一类新的原核白蛋白结合模块，被认为支持几种细菌的毒力。本文采用差示扫描量热法和等温滴定量热法对G148-GA3折叠和白蛋白结合进行了表征，以获得该医学意义模块中任何成员的最完整的热力学状态函数集。当pH 7.0缓冲时，46个氨基酸的α -螺旋结构域在72℃时熔化，在37℃时表现出边际稳定性（15 kJ/mol）。G148-GA3展开的特点是非疏水力对熵的贡献很小，并且具有较低的ΔCp（1.1 kJ/(deg mol)）。等温滴定量热法显示，该结构域已进化到最佳结合人血清白蛋白接近37°C，结合常数为1.4×10 7 M−1。G148-GA3的热力学分析表明，在折叠态和展开态之间过渡时，结构动力学和热容量的每残基变化都是非典型的小。
The third albumin binding domain of streptococcal protein G strain 148 (G148–GA3) belongs to a novel class of prokaryotic albumin binding modules that is thought to support virulence in several bacterial species. Here, we characterize G148–GA3 folding and albumin binding by using differential scanning calorimetry and isothermal titration calorimetry to obtain the most complete set of thermodynamic state functions for any member of this medically significant module. When buffered at pH 7.0 the 46-amino acid alpha-helical domain melts at 72 °C and exhibits marginal stability (15 kJ/mol) at 37 °C. G148–GA3 unfolding is characterized by small contributions to entropy from non-hydrophobic forces and a low ΔCp(1.1 kJ/(deg mol)). Isothermal titration calorimetry reveals that the domain has evolved to optimally bind human serum albumin near 37 °C with a binding constant of 1.4×10 7 M−1. Analysis of G148–GA3 thermodynamics suggests that the domain experiences atypically small per residue changes in structural dynamics and heat capacity while transiting between folded and unfolded states.