Engineering bacillus subtilis lipase for thermostability

Abstract

Structural solutions adapted by proteins to withstand changes in temp~rature newlinehave basic importance in the understanding of protein structure-function newlinerelations and also in industrial enzymology. Adaptability of protein structure is newlineexemplified by the discovery of enzymes that function at extremes of newlineenvironment. Proteins from extremophiles have become important in newlinedeciphering the strategies adapted by proteins to retain their functionalities in newlineextremes of environment. The conventional approach taken to understand newlinethermostability in proteins is to compare the structures of homologous proteins newlineisolated from thermophiles, mesophiles and psychrophiles. Such approaches newlinehave yielded insights into the importance of hydrophobicity, surface loops, salt newlinebridges, packing interactions etc. in protein thermostability. Given that the newlineenzymes have evolved over long periods during which thermal stress might not newlinehave been the only condition the protein had to adapt to, information gathered newlineby this approach is confounded by the plural effect of acquired mutations and newlineby the presence of mutations that are either silent or do not contribute to newlinethermostability. Despite several studies understanding the structural basis of newlinethermostability has proven elusive and till date, there are no well-defined rules newlineto stabilize a protein at high temperatures. Strategies that enable us to evolve newlineenzymes under defined conditions and controlled physical stresses can help newlineisolate protein variants with changes directly affecting the property of interest, newlinefor example, thermostability. These primary sequence variations can then be newlineprecisely mapped onto the structure. In vitro evolution is one such strategy, newlinewhich attempts to simulate the natural evolution in vitro in generation of variants newlineby error prone replicative processes and screening, for variants with the desired newlineproperty. newlineChapter 1 newlineGeneral aspects of protein thermostability and the structural features that newlinecontribute to protein thermostability are discussed.