Comparative analysis of the structural and functional features of endoglucanases with different temperature optima

Cellulases whose temperature optimum is shifted to extremely high or low values are of particular interest since they allow for greater flexibility in controlling the technological conditions of their industrial use. Nevertheless, the mechanisms that explain enzymatic adaptations to limiting temperatures are not fully established. The study was aimed at using bioinformatics methods to examine how the structure of microbial endoglucanases depends on two factors: the belonging of producers to different taxonomic groups of higher rank (bacteria, fungi, and archaea) and the temperature optimum of their habitat (psychro-, meso-, and thermophiles). Enzymes retrieved from Uniprot and GenBank were analyzed via pairwise and multiple sequence alignment, pairwise structural alignment, and comparison of amino acid profiles. It is shown that the sequences cluster according to the systematics of producers and do not contain patterns associated with adaptations to temperature conditions. However, the amino acid profile of proteins depends also on the temperature conditions of the microbial habitat: the frequencies of some amino acids (E, I, Y, D, and Q) differ significantly in enzymes with different temperature optima. The study also identified a set of enzymes with low sequence identity but high similarity of 3D structures. This set includes enzymes from related taxa but with different temperature optima, as well as endoglucanases from microorganisms that are systematically distant while living under similar temperature conditions. Among other things, the possible mechanisms of the observed differences between the identity scores of different structural levels of protein are discussed.

endoglucanases, psychrophiles, mesophiles, thermophiles, multiple alignment, amino acid composition