title: A folate independent role for cytosolic HPPK/DHPS upon stress in Arabidopsis thaliana.
abstract: Cytosolic HPPK/DHPS (cytHPPK/DHPS) in Arabidopsis is a functional enzyme with activity similar to its mitochondrial isoform. Genomic complementation of the cytHPPK/DHPS knockout mutant with the wild type gene led to a complete rescue of the stress sensitive mutant phenotype in seed germination tests under abiotic stress conditions. Moreover, over-expression of the gene resulted in higher germination rate under stress as compared to the wild-type, confirming its role in stress resistance. Analysis of folates in seedlings, inflorescence and dry seeds showed unchanged levels in the wild-type, mutant and over-expressor line, upon stress and normal conditions, suggesting a role for cytHPPK/DHPS distinct from folate biosynthesis and a folate-independent stress resistance mechanism. This apparently folate-independent mechanism of stress resistance points towards a possible role of pterins, since the product of HPPK/DHPS is dihydropteroate.
authors: Laboratory of Functional Plant Biology, Department of Physiology, Ghent University, KL Ledeganckstraat 35, B-9000 Gent, Belgium. oscar.navarrete@ugent.be
authors: Oscar
authors: O
authors: Navarrete
authors: Jeroen
authors: J
authors: Van Daele
authors: Christophe
authors: C
authors: Stove
authors: Willy
authors: W
authors: Lambert
authors: Dominique
authors: D
authors: Van Der Straeten
authors: Sergei
authors: S
authors: Storozhenko
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D005492:Folic Acid / Q000737:chemistry / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000235:genetics; D015394:Molecular Structure; D009097:Multienzyme Complexes / Q000378:metabolism*; D012639:Seeds / Q000235:genetics / Q000378:metabolism
chemical_list: C105176:6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase-7,8-dihydropteroate synthase; D009097:Multienzyme Complexes; D005492:Folic Acid