Title: Structure and Function of -1,3-Glucanase from Streptomyces thermodiastaticus HF3-3

Biography:

Ph.D. student in biotechnology at Ritsumeikan University who has passion to innovate and to develop the new innovation and products by using microorganism. Research experiences include protein purification, production recombinant protein, protein crystallization, genetic engineering, isolation, screening, culture, and identification microorganisms.

Abstract

a-1,3-glucan (mutan) is a water-insoluble, linear a-1,3-linked homopolymer of glucose, which is the main component of extracellular polysaccharide, was synthesized from sucrose by Streptococcus mutans via glycosyltransferases (GTFs) that are cause of dental plague in human. It has also been found in fungi as a component of cell wall, carbon source and virulent factor of pathogenic fungi. Considering from this background, we have interested in studying a-1,3-glucanase (mutanase) that can hydrolyze a-1,3-glycosidic bond of a-1,3-glucan. In the previous study was determined the amino acid sequence of GH 87 a-1,3-glucanase from Streptomyces thermodiastaticus HF3-3 (Agl-ST2) which was categorized as a new group of a-1,3-glucanase, multi-domains enzyme including N-terminal binding domain, carbohydrate binding module family 35 (CBM35), C-terminal catalytic domain and discoidin domain (DS), respectively. The comparison of Agl-ST2 with the related enzymes revealed high similarity to mycodextranase (85%), whereas had low homology with the known a-1,3-glucanase. But the properties indicated that Agl-ST2 belongs to a-1,3-glucanase. Since Agl-ST1 is generated from Agl-ST2 by truncation of DS region, Agl-ST1 has the same multi-domain as Agl-ST2 but without DS. In this study to understand domain structure and function of Agl-ST (1&2), we determined each domain structure and function of the Agl-STs in the a-1,3-glucan binding and hydrolysis by constructing several domain deletions and site-directed mutation in catalytic domain. The results showed that Agl-ST with site-directed mutation at the critical amino residues had little activities of hydrolysis a-1,3-glucan, while the enzymes lacking catalytic domain lower binding activities than the wild type .