Linked Life Data

15686515

Source:http://linkedlifedata.com/resource/pubmed/id/15686515

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2005-2-2
pubmed:abstractText
The heterotetrameric, allosterically regulated enzyme, adenosine-5'-diphosphoglucose pyrophosphorylase (AGPase) catalyzes the rate-limiting step in starch synthesis. Despite vast differences in allosteric properties and a long evolutionary separation, heterotetramers of potato small subunit and maize large subunit have activity comparable to either parent in an Escherichia coli expression system. In contrast, co-expression of maize small subunit with the potato large subunit produces little activity as judged by in vivo activity stain. To pinpoint the region responsible for differential activity, we expressed chimeric maize/potato small subunits in E. coli. This identified a 55-amino acid motif of the potato small subunit that is critical for glycogen production when expressed with the potato large subunit. Potato and maize small subunit sequences differ at five amino acids in this motif. Replacement experiments revealed that at least four amino acids of maize origin were required to reduce staining. An AGPase composed of a chimeric potato small subunit containing the 55-amino acid maize motif with the potato large subunit exhibited substantially less affinity for the substrates, glucose-1-phosphate and ATP and an increased Ka for the activator, 3-phosphoglyceric acid. Placement of the potato motif into the maize small subunit restored glycogen synthesis with the potato large subunit. Hence, a small polymorphic motif within the small subunit influences both catalytic and allosteric properties by modulating subunit interactions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0960-7412
pubmed:author
pubmed:issnType
Print
pubmed:volume
41
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
501-11
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
A polymorphic motif in the small subunit of ADP-glucose pyrophosphorylase modulates interactions between the small and large subunits.
pubmed:affiliation
Program in Plant Molecular and Cellular Biology and Horticultural Sciences, University of Florida, PO Box 110690, 2211 Fifield Hall, Gainesville, FL 32611, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't