Bioinformatics and functional selection of GH77 4- α-glucanotransferases for potato starch modification

N Biotechnol. 2023 Dec 12:S1871-6784(23)00070-5. doi: 10.1016/j.nbt.2023.12.002. Online ahead of print.ABSTRACT4-α-glucanotransferases (4αGTs, EC 2.4.1.25) from glycoside hydrolase family 77 (GH77) catalyze chain elongation of starch amylopectin chains and can be utilized to structurally modify starch to tailor its gelation properties. The potential relationship between the structural design of 4αGTs and functional starch modification is unknown. Here, family GH77 was mined in silico for enzyme candidates based on sub-grouping guided by Conserved Unique Peptide Patterns (CUPP) bioinformatics categorization. From +12,000 protein sequences a representative set of 27 4αGTs, representing four different domain architectures, different bacterial origins and diverse CUPP groups, was selected for heterologous expression and further study. Most of the enzymes catalyzed starch modification, but their efficacies varied substantially. Five of the 4αGTs were characterized in detail, and their action was compared to that of the industrial benchmark enzyme, Tt4αGT (CUPP 77_1.2), from Thermus thermophilus. Reaction optima of the five 4αGTs ranged from ∼40°C-60°C and pH 7.3-8.5. Several were stable for a minimum 4h at 70 °C. Domain architecture type A proteins, consisting only of a catalytic domain, had high thermal stability and high starch modification ability. All five novel 4αGTs (and Tt4αGT) induced enhanced gelling of potato starch. One, At4αGT from Azospirillum thermophi...

Source: New Biotechnology - December 14, 2023 Category: Biotechnology Authors: Stefan Jarl Christensen Michael Schmidt Madsen Signe Schram Zinck Christinne Hedberg Ole Bandsholm S ørensen Birte Svensson Anne S Meyer Source Type: research