title: Structural Rigidity and Protein Thermostability in Variants of Lipase A from Bacillus subtilis.
abstract: Understanding the origin of thermostability is of fundamental importance in protein biochemistry. Opposing views on increased or decreased structural rigidity of the folded state have been put forward in this context. They have been related to differences in the temporal resolution of experiments and computations that probe atomic mobility. Here, we find a significant (p = 0.004) and fair (R2 = 0.46) correlation between the structural rigidity of a well-characterized set of 16 mutants of lipase A from Bacillus subtilis (BsLipA) and their thermodynamic thermostability. We apply the rigidity theory-based Constraint Network Analysis (CNA) approach, analyzing directly and in a time-independent manner the statics of the BsLipA mutants. We carefully validate the CNA results on macroscopic and microscopic experimental observables and probe for their sensitivity with respect to input structures. Furthermore, we introduce a robust, local stability measure for predicting thermodynamic thermostability. Our results complement work that showed for pairs of homologous proteins that raising the structural stability is the most common way to obtain a higher thermostability. Furthermore, they demonstrate that related series of mutants with only a small number of mutations can be successfully analyzed by CNA, which suggests that CNA can be applied prospectively in rational protein design aimed at higher thermodynamic thermostability.
authors.affiliation: Institute of Pharmaceutical and Medical Chemistry, Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Prakash Chandra
authors.initials: PC
authors.lastname: Rathi
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-University, Düsseldorf, Germany; Institute of Bio- and Geosciences IBG-1: Biotechnology, Research Centre Jülich, Jülich, Germany.
authors.forename: Karl-Erich
authors.initials: KE
authors.lastname: Jaeger
authors.affiliation: Institute of Pharmaceutical and Medical Chemistry, Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Gohlke
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D004795:Enzyme Stability / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics*; D006358:Hot Temperature; D008049:Lipase / Q000235:genetics*; D056004:Molecular Dynamics Simulation; D009154:Mutation / Q000235:genetics; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D008049:Lipase