G148-GA3: A streptococcal virulence module with atypical thermodynamics of folding optimally binds human serum albumin at physiological temperatures

被引：16

作者：

Rozak, DA ^{[1
]}

Orban, J ^{[1
]}

Bryan, PN ^{[1
]}

机构：

[1] Univ Maryland, Inst Biotechnol, Ctr Adv Res Biotechnol, Rockville, MD 20850 USA

来源：

BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS | 2005年 / 1753卷 / 02期

关键词：

streptococcus; Finegoldia magna; protein G; albumin binding; protein stability; calorimetry;

D O I：

10.1016/j.bbapap.2005.10.005

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

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 degrees C and exhibits marginal stability (15 kJ/mol) at 37 degrees C. G148-GA3 unfolding is characterized by small contributions to entropy from non-hydrophobic forces and a low Delta C-p (1.1 kJ/(deg mol)). Isothermal titration calorimetry reveals that the domain has evolved to optimally bind human serum albumin near 37 degrees C with a binding constant of 1.4 x 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. (c) 2005 Elsevier B.V. All rights reserved.

引用

页码：226 / 233

页数：8

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