Crystal structure of a novel homodimeric l‐ribulose 3‐epimerase from Methylomonus sp. Issue 6 (1st May 2021)

• Record Type: Journal Article
• Authors: Yoshida, Hiromi; Yoshihara, Akihide; Kato, Shiro; Mochizuki, Susumu; Akimitsu, Kazuya; Izumori, Ken; Kamitori, Shigehiro
• Editors: Wlodawer, Alex
• Is Part Of: FEBS open bio. Volume 11:Issue 6(2021)
• Page Start: 1621
• Page End: 1637
• Publication Date: 2021-05-01
• Subjects: d‐allulose -- d‐allulose 3‐epimerase -- l‐ribulose 3 epimerase -- rare sugar -- X‐ray structure -- β/α‐barrel; Molecular biology -- Periodicals; Cytology -- Periodicals; Life sciences -- Periodicals; Biological Science Disciplines -- Periodicals; Molecular Biology -- Periodicals; Cell Biology -- Periodicals; Cytology; Life sciences; Molecular biology; Periodicals; 572.805
• DOI: 10.1002/2211-5463.13159
• Languages: English
• ISSNs: 2211-5463

Abstract

Abstract : d ‐Allulose has potential as a low‐calorie sweetener which can suppress fat accumulation. Several enzymes capable of d ‐allulose production have been isolated, including d ‐tagatose 3‐epimerases. Here, we report the isolation of a novel protein from Methylomonas sp. expected to be a putative enzyme based on sequence similarity to ketose 3‐epimerase. The synthesized gene encoding the deduced ketose 3‐epimerase was expressed as a recombinant enzyme in Escherichia coli, and it exhibited the highest enzymatic activity toward l ‐ribulose, followed by d ‐ribulose and d ‐allulose. The X‐ray structure analysis of l ‐ribulose 3‐epimerase from Methylomonas sp. (MetLRE) revealed a homodimeric enzyme, the first reported structure of dimeric l ‐ribulose 3‐epimerase. The monomeric structure of MetLRE is similar to that of homotetrameric l ‐ribulose 3‐epimerases, but the short C‐terminal α‐helix of MetLRE is unique and different from those of known l ‐ribulose 3 epimerases. The length of the C‐terminal α‐helix was thought to be involved in tetramerization and increasing stability; however, the addition of residues to MetLRE at the C terminus did not lead to tetramer formation. MetLRE is the first dimeric l ‐ribulose 3‐epimerase identified to exhibit high relative activity toward d ‐allulose. Abstract : d ‐Allulose has potential as a low‐calorie sweetener which can suppress fat accumulation. The enzymes capable of d ‐allulose production have attracted attention. Here, we report the X‐ray structure of a novel l ‐ribulose 3‐epimerase from Methylomonas sp. (MetLRE) which also has enzymatic activity towards d ‐allulose, showing that MetLRE is the first dimeric l ‐ribulose 3‐epimerase identified to exhibit high relative activity toward d ‐allulose. ​