当前位置： SCI文献检索 > PLANT MOLECULAR BIOLOGY期刊下所有文献 > Heterologous co-expression in E. coli of isoamylase genes from cassava Manihot esculenta Crantz 'KU50' achieves enzyme-active heteromeric complex formation.

Heterologous co-expression in E. coli of isoamylase genes from cassava Manihot esculenta Crantz 'KU50' achieves enzyme-active heteromeric complex formation.

Abstract：

KEY MESSAGE:Cloning of two isoamylase genes, MeISA1 and MeISA2, from cassava (Manihot esculenta Crantz) tubers, accompanied by their co-expression in E. coli demonstrates a requirement for heteromeric complex formation to achieve debranching activity. Starch debranching enzyme (DBE) or isoamylase (ISA) (EC.3.2.1.68), an important enzyme in starch metabolism, catalyses the hydrolysis of α-1,6 glycosidic linkages of amylopectin. Isoforms of ISAs have been reported in higher plants and algae (Fujita et al. in Planta 208:283-293, 1999; Hussain et al. in Plant Cell 15:133-149, 2003; Ishizaki et al. in Agric Biol Chem 47:771-779, 1983; Mouille et al. in Plant Cell 8:1353-1366, 1996). In the current work, cassava ISA genes were isolated from cDNA generated from total RNA from tubers of Manihot esculanta Crantz cultivar KU50. MeISA1 and MeISA2 were successfully amplified and cloned into a pETDuet1 vector. The putative MeISA1 and MeISA2 proteins comprised 763 and 882 amino acids, with substantial similarity to StISA1 and StISA2 from potato (84.4% and 68.9%, respectively). Recombinant MeISA1 and MeISA2 were co-expressed in Escherichia coli SoluBL21 (DE3). HistrapTM-Purified rMeISA1 and rMeISA2 showed approximate molecular weights of 87 and 99 kDa, respectively, by SDS-PAGE. Debranching activity was only detectable in the column fractions where both recombinant ISA isoforms were present. The heteromeric DBE from crude extracts of 4-5 h induced cultures analysed by gel filtration chromatography and western blot showed combinations of rMeISA1 and rMeISA2 at ratios of 1:1 to 4:1. Pooled fractions with DBE activity were used for enzyme characterisation, which showed that the enzyme was specific for amylopectin, with optimum activity at 37 °C and pH 7.0. Enzyme activity was enhanced by Co2+, Mg2+ and Ca2+, but was strongly inhibited by Cu2+. Debranched amylopectin products showed chain length distributions typical of plant DBE.

journal_name

Plant Mol Biol

journal_title

Plant molecular biology

authors

Panpetch P,Field RA,Limpaseni T

doi

10.1007/s11103-018-0707-z

subject

Has Abstract

pub_date

2018-03-01 00:00:00

pages

417-427

issue

4-5

eissn

0167-4412

issn

1573-5028

pii

10.1007/s11103-018-0707-z

journal_volume

pub_type

杂志文章

在线工具

Heterologous co-expression in E. coli of isoamylase genes from cassava Manihot esculenta Crantz 'KU50' achieves enzyme-active heteromeric complex formation.