Cloning and characterization of two rhamnose synthases from Sorbus aucuparia
10.16438/j.0513-4870.2020-1247
- VernacularTitle:欧洲花楸中鼠李糖合成酶基因SaRHMs的克隆及鉴定
- Author:
Liang-yun ZHOU
1
;
Jia-xing LI
1
,
2
;
Jian YANG
3
;
Sheng WANG
3
;
Chao-geng LÜ
3
;
Lan-ping GUO
3
Author Information
1. Comprehensive Experimental Station of Guangzhou, Chinese Materia Medica, China Agriculture Research System, School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, China
2. State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China
3. State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China
- Publication Type:Research Article
- Keywords:
italic>Sorbus aucuparia;
rhamnose synthase;
UDP-Rha;
function characterization
- From:
Acta Pharmaceutica Sinica
2021;56(1):328-335
- CountryChina
- Language:Chinese
-
Abstract:
Rhamnose synthase (RHM) is a key enzyme in the biosynthesis of uridine diphosphate rhamnose (UDP-Rha), reversibly converting uridine diphosphate-glucose (UDP-Glc) into UDP-Rha in the presence of NADH or NADPH. In this research, yeast extract (YE) was used to stimulate Sorbus aucuparia suspension cells. Based on a previous study of the transcriptome database of S. aucuparia suspension cells, two RHMs were cloned from S. aucuparia and named SaRHM1 (GenBank No.: MK213340) and SaRHM2 (GenBank No.: MK213341). The SaRHM1 gene contained a 2 007 bp open reading frame (ORF) encoding a polypeptide of 668 amino acids with a molecular weight of 75.25 kD, and a theoretical isoelectric point (pI) of 7.24. The SaRHM2 gene contained a 2 040 bp ORF encoding a polypeptide of 679 amino acids with a molecular weight of 76.26 kD and pI of 6.41. Bioinformatic analysis indicated that SaRHM1 and SaRHM2 contained two special sequences of GxxGxxG/A and YxxxK. Multiple sequence alignments and phylogenetic trees show that SaRHM1 and SaRHM2 have high sequence similarity with other plant species of RHMs. The results of enzyme activity assays in vitro revealed that both recombinant SaRHM1 and SaRHM2 are able to convert UDP-Glc into UDP-Rha. SaRHMs displayed maximum activity at 40 ℃ and a pH of 8 and 9, respectively. The Km values of SaRHM1 and SaRHM2 for UDP-Glc were 212.4 ± 56.70 and 361.0 ± 63.74 μmol·L-1, respectively, with Vmax values of 235.5 ± 18.98 and 516.5 ± 22.30 nmol·min-1·μg-1, respectively. This study reports the cloning and sequencing of RHMs from S. aucuparia and verifies their function, which likely provide rhamnose donors for the subsequent biosynthesis of rhamnosides.
