Modulation of amylose content by structure‐based modification of OsGBSS1 activity in rice (Oryza sativa L.). Issue 9 (22nd July 2014)

• Record Type: Journal Article
• Authors: Liu, Derui; Wang, Wei; Cai, Xiuling
• Is Part Of: Plant biotechnology journal. Volume 12:Issue 9(2014:Dec.)
• Page Start: 1297
• Page End: 1307
• Publication Date: 2014-07-22
• Subjects: Plant biotechnology -- Periodicals; Plant genetic engineering -- Periodicals; 630.272
• DOI: 10.1111/pbi.12228
• Languages: English
• ISSNs: 1467-7644

Abstract

<abstract abstract-type="main" id="pbi12228-abs-0001"> <title>Summary</title> <p>The rice <italic>Waxy</italic> (<italic>Wx</italic>) gene encodes granule‐bound starch synthase 1 (EC 2.4.1.242), OsGBSS1, which is responsible for amylose synthesis in rice seed endosperm. In this study, we determined the functional contribution of eight amino acids on the activity of OsGBSS1 by introducing site‐directed mutated <italic>Wx</italic> gene constructs into the <italic>wx</italic> mutant glutinous rice. The eight amino acid residues are suspected to play roles in OsGBSS1 structure maintenance or function based on homologous enzyme sequence alignment and homology modelling. Both OsGBSS1 activity and amylose content were analysed in homozygous transgenic lines carrying the mutated <italic>OsGBSS1</italic> (<italic>Wx</italic>) genes. Our results indicate that mutations at diverse sites in OsGBSS1 reduces its activity by affecting its starch‐binding capacity, its ADP‐glucose‐binding capability or its protein stability. Our results shed new light on the structural basis of OsGBSS1 activity and the mechanisms of OsGBSS1 activity on amylose synthesis <italic>in vivo</italic>. This study also demonstrates that it is feasible to finely modulate amylose content in rice grains by modifying the OsGBSS1 activity.</p> </abstract>