RRC ID 1880
Author Muñoz FJ, Baroja-Fernández E, Morán-Zorzano MT, Alonso-Casajús N, Pozueta-Romero J.
Title Cloning, expression and characterization of a Nudix hydrolase that catalyzes the hydrolytic breakdown of ADP-glucose linked to starch biosynthesis in Arabidopsis thaliana.
Journal Plant Cell Physiol.
Abstract 'Nudix' hydrolases are widely distributed nucleotide pyrophosphatases that possess a conserved GX5EX7REUXEEXGU motif where U is usually isoleucine, leucine or valine. Among them, Escherichia coli ADP-sugar pyrophosphatase (ASPP) has been shown to catalyze the hydrolytic breakdown of ADP-glucose linked to bacterial glycogen biosynthesis. Comparisons of the 31 different Nudix-encoding sequences of the Arabidopsis genome with those coding for known bacterial and mammalian ASPPs identified one sequence possessing important divergences in the Nudix motif that, once expressed in E. coli, produced a protein with ASPP activity. This protein, designated as AtASPP, shares strong homology with hypothetical rice and potato proteins, indicating that ASPPs are widely distributed in both mono- and dicotyledonous plants. As a first step to test the possible involvement of plant ASPPs in regulating the intracellular levels of ADP-glucose linked to starch biosynthesis, we produced and characterized AtASPP-overexpressing Arabidopsis plants. Source leaves from these plants exhibited a large reduction in the levels of both ADP-glucose and starch, indicating that plant ASPPs catalyze the hydrolytic breakdown of a sizable pool of ADP-glucose linked to starch biosynthesis. No pleiotropic changes in maximum catalytic activities of enzymes closely linked to starch metabolism could be detected in AtASPP-overexpressing leaves. The overall information provides the first evidence for the existence of plant Nudix hydrolases that have access to an intracellular pool of ADP-glucose linked to starch biosynthesis.
Volume 47(7)
Pages 926-34
Published 2006-7
DOI 10.1093/pcp/pcj065
PII pcj065
PMID 16774931
MeSH Adenosine Diphosphate Glucose / metabolism* Amino Acid Motifs / genetics Amino Acid Sequence Arabidopsis / genetics* Arabidopsis / metabolism* Arabidopsis Proteins / genetics Arabidopsis Proteins / physiology Cloning, Molecular Escherichia coli Proteins / genetics Escherichia coli Proteins / physiology Gene Expression Profiling Gene Expression Regulation, Enzymologic Gene Expression Regulation, Plant Genes, Plant / genetics Glucose-1-Phosphate Adenylyltransferase / genetics Glucose-1-Phosphate Adenylyltransferase / physiology Molecular Sequence Data Plant Leaves / metabolism Pyrophosphatases / genetics* Pyrophosphatases / physiology Recombinant Proteins / genetics Starch / metabolism* Substrate Specificity Sucrose / metabolism
IF 4.059
Times Cited 18
Arabidopsis / Cultured plant cells, genes pda04474 pda03462