EXPRESSION, ORGANIZATION AND STRUCTURE OF THE GENES ENCODING THE WAXYPROTEIN (GRANULE-BOUND STARCH SYNTHASE) IN WHEAT

Citation
C. Ainsworth et al., EXPRESSION, ORGANIZATION AND STRUCTURE OF THE GENES ENCODING THE WAXYPROTEIN (GRANULE-BOUND STARCH SYNTHASE) IN WHEAT, Plant molecular biology, 22(1), 1993, pp. 67-82
Citations number
43
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences",Biology
Journal title
ISSN journal
0167-4412
Volume
22
Issue
1
Year of publication
1993
Pages
67 - 82
Database
ISI
SICI code
0167-4412(1993)22:1<67:EOASOT>2.0.ZU;2-F
Abstract
A full-length cDNA clone representing the waxy protein (GBSSI) isolate d from a hexaploid wheat developing grain cDNA library has been used t o characterise the organisation and expression of the waxy genes in wh eat. The genes are organised as a triplicate set of single copy homeol oci on chromosome arms 4AL, 7AS and 7DS. The genes are active througho ut grain filling where the main 2.3 kb transcript accumulates to high levels. The 2.3 kb transcript is not expressed in leaves where the pre sence of a related, but less homologous, transcript of 1.6 kb suggests that a different set of genes operates. Gel analysis and purification of the waxy protein isolated from starch granules, followed by N-term inal amino acid sequencing in conjunction with data from hybrid select translation experiments and sequence analysis of the cDNA, shows that the mature protein has a molecular weight of 60kDa (615 amino acids) and that the preprotein includes a chloroplast/amyloplast transit pept ide of 7kDa (75 amino acids). Analysis of the derived amino acid seque nce and alignment with five other plant waxy proteins shows that they exhibit substantial homology. The wheat protein differs from all other s in that it contains an 11 amino acid insertion towards the N-terminu s. The protein contains the conserved motif KTGGL found in other waxy proteins and which has been implicated as the active site in glycogen synthase.