Characterization of a unique pH-dependent amylosucrase from Deinococcus cellulosilyticus

• Published in: International journal of biological macromolecules 2024-06, Vol.269 (Pt 2), p.131834, Article 131834
• Main Authors: Lee, Chang-Young, So, Yun-Sang, Lim, Min-Cheol, Jeong, Soyoung, Yoo, Sang-Ho, Park, Choen-Seok, Jung, Jong-Hyun, Seo, Dong-Ho
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amylosucrase; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Cloning, Molecular; Deinococcus - enzymology; Deinococcus - genetics; Deinococcus cellulosilyticus; Disaccharides; Enzyme Stability; Glucosyltransferases - chemistry; Glucosyltransferases - genetics; Glucosyltransferases - metabolism; Hydrogen-Ion Concentration; Isomaltose - analogs & derivatives; Isomaltose - chemistry; Isomaltose - metabolism; Kinetics; Molecular Weight; Oligomeric state; Protein Structure, Secondary; Substrate Specificity; Sucrose - metabolism
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.131834

The amylosucrase (ASase, EC 2.4.1.4) utilizes sucrose as the sole substrate to catalyze multifunctional reactions. It can naturally synthesize α-1,4-linked glucans such as amylose as well as sucrose isomers with more favorable properties than sucrose with a lower intestinal digestibility and non-cariogenic properties. The amino acid sequence of the asase gene from Deinococcus cellulosilyticus (DceAS) exhibits low homology with those of other ASases from other Deinococcus species. In this study, we cloned and expressed DceAS and demonstrated its high activity at pH 6 and pH 8 and maintained stability. It showed higher polymerization activity at pH 6 than at pH 8, but similar isomerization activity and produced more turanose and trehalulose at pH 6 than at pH 8 and produced more isomaltulose at pH 8. Furthermore, the molecular weight of DceAS was 226.6 kDa at pH 6 and 145.5 kDa at pH 8, indicating that it existed as a trimer and dimer, respectively under those conditions. Additionally, circular dichroism spectra showed that the DceAS secondary structure was different at pH 6 and pH 8. These differences in reaction products at different pHs can be harnessed to naturally produce sucrose alternatives that are more beneficial to human health. •Evaluation of pH-dependent properties of amylosucrase from D. cellulosilyticus.•Understanding differences in product formation by DceAS at pH 6 and 8•High isomerization activity of DceAS in 50 mM sodium citrate buffer at pH 6•Increased trehalulose/insoluble glucan ratio in 50 mM sodium citrate buffer at pH 6