標題: Protein Thermal Stability Enhancement by Designing Salt Bridges: A Combined Computational and Experimental Study
作者: Lee, Chi-Wen
Wang, Hsiu-Jung
Hwang, Jenn-Kang
Tseng, Ching-Ping
生物資訊及系統生物研究所
生醫工程研究所
Institude of Bioinformatics and Systems Biology
Institute of Biomedical Engineering
公開日期: 13-十一月-2014
摘要: Protein thermal stability is an important factor considered in medical and industrial applications. Many structural characteristics related to protein thermal stability have been elucidated, and increasing salt bridges is considered as one of the most efficient strategies to increase protein thermal stability. However, the accurate simulation of salt bridges remains difficult. In this study, a novel method for salt-bridge design was proposed based on the statistical analysis of 10,556 surface salt bridges on 6,493 X-ray protein structures. These salt bridges were first categorized based on pairing residues, secondary structure locations, and C alpha-C alpha distances. Pairing preferences generalized from statistical analysis were used to construct a salt-bridge pair index and utilized in a weighted electrostatic attraction model to find the effective pairings for designing salt bridges. The model was also coupled with B-factor, weighted contact number, relative solvent accessibility, and conservation prescreening to determine the residues appropriate for the thermal adaptive design of salt bridges. According to our method, eight putative salt-bridges were designed on a mesophilic beta-glucosidase and 24 variants were constructed to verify the predictions. Six putative salt-bridges leaded to the increase of the enzyme thermal stability. A significant increase in melting temperature of 8.8, 4.8, 3.7, 1.3, 1.2, and 0.7 degrees C of the putative salt-bridges N437K-D49, E96R-D28, E96K-D28, S440K-E70, T231K-D388, and Q277E-D282 was detected, respectively. Reversing the polarity of T231K-D388 to T231D-D388K resulted in a further increase in melting temperatures by 3.6 degrees C, which may be caused by the transformation of an intra-subunit electrostatic interaction into an inter-subunit one depending on the local environment. The combination of the thermostable variants (N437K, E96R, T231D and D388K) generated a melting temperature increase of 15.7 degrees C. Thus, this study demonstrated a novel method for the thermal adaptive design of salt bridges through inference of suitable positions and substitutions.
URI: http://dx.doi.org/10.1371/journal.pone.0112751
http://hdl.handle.net/11536/124278
ISSN: 1932-6203
DOI: 10.1371/journal.pone.0112751
期刊: PLOS ONE
Issue: 11
顯示於類別:期刊論文


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