The absence of molybdenum cofactor sulfuration is the primary cause of the flacca phenotype in tomato plants

• DOI: 10.1046/j.1365-313x.2002.01363.x
• Publication Date: 2003-03-12T22:07:27Z
• Authors: Moshe Sagi; Claudio Scazzocchio; Robert Fluhr
• Keywords: Molybdenum Cofactor; Aldehyde oxidase

Summary The molybdenum cofactor (MoCo)‐containing enzymes aldehyde oxidase (AO; EC 1.2.3.1) and xanthine dehydrogenase (XDH; 1.2.1.37) require for activity a sulfuration step that inserts terminal sulfur ligand into the MoCo. tomato flacca mutation was originally isolated as wilty phenotype due to lack of abscisic acid (ABA) is related simultaneous loss AO XDH activities. An expressed sequence tag candidate from selected on basis homology sulfurases animals, fungi recently Arabidopsis genes LOS5/ABA3 . homologue maps single gene bottom chromosome 7, consistent with genetic location mutation. structure FLACCA shows multidomain protein an N‐terminal NifS‐like sulfurase domain; mammal‐specific intermediate section; C‐terminus containing conserved motifs. Prominent among these are molybdopterin oxidoreductases thioredoxin redox‐active centre/iron–sulfur‐binding region signatures which may be relevant specific Indeed, molecular analysis identifies in highly motif located C‐terminus. Activity gel assays show throughout plant. Transient stable complementation aba3 mutants Aspergillus nidulans hxB yielded full, partial tissue‐specific types Mo‐hydroxylase Restoration root alone sufficient augment plant ABA content rectify wild‐type phenotype. Thus pleiotropic requiring sulfurated