Staff View: Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans

Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans

Isoamylases are debranching enzymes that hydrolyze � -1,6 linkages in � -1,4/ � -1,6–linked glucan polymers. In plants, they have been shown to be required for the normal synthesis of amylopectin, although the precise manner in which they influence starch synthesis is still debated. cDNA clo...

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Main Authors:	Hasnain, Hussain, Alexandra, Mant, Robert, Seale, Sam, Zeeman, Edward, Hinchliffe, Anne, Edwards, Christopher, Hylton, Stephen, Bornemann, Alison, M. Smith, Cathie, Martin, Regla, Bustos
Format:	E-Article
Language:	English
Published:	US National Library of Medicine National Institutes of Health Search databaseSearch term Search 2003
Subjects:	S Agriculture (General)
Online Access:	http://ir.unimas.my/id/eprint/9985/1/Three%20isoforms%20of%20isoamylase%20contribute%20different%20catalytic%20properties%20for%20the%20debranching%20of%20potato%20glucans%20%28abstract%29.pdf http://ir.unimas.my/id/eprint/9985/ http://www.ncbi.nlm.nih.gov/pubmed/12509527
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spelling	my.unimas.ir.99852015-12-08T06:57:16Z http://ir.unimas.my/id/eprint/9985/ Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans Hasnain, Hussain Alexandra, Mant Robert, Seale Sam, Zeeman Edward, Hinchliffe Anne, Edwards Christopher, Hylton Stephen, Bornemann Alison, M. Smith Cathie, Martin Regla, Bustos S Agriculture (General) Isoamylases are debranching enzymes that hydrolyze � -1,6 linkages in � -1,4/ � -1,6–linked glucan polymers. In plants, they have been shown to be required for the normal synthesis of amylopectin, although the precise manner in which they influence starch synthesis is still debated. cDNA clones encoding three distinct isoamylase isoforms (Stisa1, Stisa2, and Stisa3) have been identified from potato. The expression patterns of the genes are consistent with the possibility that they all play roles in starch synthesis. Analysis of the predicted sequences of the proteins suggested that only Stisa1 and Stisa3 are likely to have hydrolytic activity and that there probably are differences in substrate specificity between these two isoforms. This was confirmed by the expression of each isoamylase in Escherichia coli and characterization of its activity. Partial purification of isoamylase activity from potato tubers showed that Stisa1 and Stisa2 are associated as a multimeric enzyme but that Stisa3 is not associated with this enzyme complex. Our data suggest that Stisa1 and Stisa2 act together to debranch soluble glucan during starch synthesis. The catalytic specificity of Stisa3 is distinct from that of the multimeric enzyme, indicating that it may play a different role in starch metabolism. US National Library of Medicine National Institutes of Health Search databaseSearch term Search 2003 E-Article NonPeerReviewed text en http://ir.unimas.my/id/eprint/9985/1/Three%20isoforms%20of%20isoamylase%20contribute%20different%20catalytic%20properties%20for%20the%20debranching%20of%20potato%20glucans%20%28abstract%29.pdf Hasnain, Hussain and Alexandra, Mant and Robert, Seale and Sam, Zeeman and Edward, Hinchliffe and Anne, Edwards and Christopher, Hylton and Stephen, Bornemann and Alison, M. Smith and Cathie, Martin and Regla, Bustos (2003) Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans. The Plant Cell, 15 (1). pp. 133-149. ISSN 1532-298X http://www.ncbi.nlm.nih.gov/pubmed/12509527 www.plantcell.org/cgi/doi/10.1105/tpc.006635.
institution	Universiti Malaysia Sarawak
building	Centre for Academic Information Services (CAIS)
collection	Institutional Repository
continent	Asia
country	Malaysia
content_provider	Universiti Malaysia Sarawak
content_source	UNIMAS Institutional Repository
url_provider	http://ir.unimas.my/
language	English
topic	S Agriculture (General)
spellingShingle	S Agriculture (General) Hasnain, Hussain Alexandra, Mant Robert, Seale Sam, Zeeman Edward, Hinchliffe Anne, Edwards Christopher, Hylton Stephen, Bornemann Alison, M. Smith Cathie, Martin Regla, Bustos Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans
description	Isoamylases are debranching enzymes that hydrolyze � -1,6 linkages in � -1,4/ � -1,6–linked glucan polymers. In plants, they have been shown to be required for the normal synthesis of amylopectin, although the precise manner in which they influence starch synthesis is still debated. cDNA clones encoding three distinct isoamylase isoforms (Stisa1, Stisa2, and Stisa3) have been identified from potato. The expression patterns of the genes are consistent with the possibility that they all play roles in starch synthesis. Analysis of the predicted sequences of the proteins suggested that only Stisa1 and Stisa3 are likely to have hydrolytic activity and that there probably are differences in substrate specificity between these two isoforms. This was confirmed by the expression of each isoamylase in Escherichia coli and characterization of its activity. Partial purification of isoamylase activity from potato tubers showed that Stisa1 and Stisa2 are associated as a multimeric enzyme but that Stisa3 is not associated with this enzyme complex. Our data suggest that Stisa1 and Stisa2 act together to debranch soluble glucan during starch synthesis. The catalytic specificity of Stisa3 is distinct from that of the multimeric enzyme, indicating that it may play a different role in starch metabolism.
format	E-Article
author	Hasnain, Hussain Alexandra, Mant Robert, Seale Sam, Zeeman Edward, Hinchliffe Anne, Edwards Christopher, Hylton Stephen, Bornemann Alison, M. Smith Cathie, Martin Regla, Bustos
author_facet	Hasnain, Hussain Alexandra, Mant Robert, Seale Sam, Zeeman Edward, Hinchliffe Anne, Edwards Christopher, Hylton Stephen, Bornemann Alison, M. Smith Cathie, Martin Regla, Bustos
author_sort	Hasnain, Hussain
title	Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans
title_short	Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans
title_full	Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans
title_fullStr	Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans
title_full_unstemmed	Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans
title_sort	three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans
publisher	US National Library of Medicine National Institutes of Health Search databaseSearch term Search
publishDate	2003
url	http://ir.unimas.my/id/eprint/9985/1/Three%20isoforms%20of%20isoamylase%20contribute%20different%20catalytic%20properties%20for%20the%20debranching%20of%20potato%20glucans%20%28abstract%29.pdf http://ir.unimas.my/id/eprint/9985/ http://www.ncbi.nlm.nih.gov/pubmed/12509527
_version_	1644510861942849536
score	13.211869

Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans

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