Functional Analysis of a Predicted Flavonol Synthase Gene Family in Arabidopsis

• Published in: Plant physiology (Bethesda) Vol. 147; no. 3; pp. 1046 - 1061
• Main Authors: Owens, Daniel K, Alerding, Anne B, Crosby, Kevin C, Bandara, Aloka B, Westwood, James H, Winkel, Brenda S.J
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01-07-2008; American Society of Plant Physiologists
• Subjects: Amino Acid Sequence; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis thaliana; Biochemical Processes and Macromolecular Structures; Biological and medical sciences; Biosynthesis; Complementary DNA; Enzymes; Flavonoids; Flavonols; Flavonols - biosynthesis; Fundamental and applied biological sciences. Psychology; Gene Duplication; Gene Expression; Genes; Genes. Genome; Genomes; Isoenzymes - genetics; Isoenzymes - metabolism; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Multigene Family; Oxidoreductases - genetics; Oxidoreductases - metabolism; Phenotype; Plant Proteins - genetics; Plant Proteins - metabolism; Plant roots; Plants; Seedlings; Two-Hybrid System Techniques; Spermatophyta; Gene; Cruciferae; Arabidopsis; Dicotyledones; Angiospermae
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.108.117457

The genome of Arabidopsis (Arabidopsis thaliana) contains five sequences with high similarity to FLAVONOL SYNTHASE1 (AtFLS1), a previously characterized flavonol synthase gene that plays a central role in flavonoid metabolism. This apparent redundancy suggests the possibility that Arabidopsis uses multiple isoforms of FLS with different substrate specificities to mediate the production of the flavonols, quercetin and kaempferol, in a tissue-specific and inducible manner. However, biochemical and genetic analysis of the six AtFLS sequences indicates that, although several of the members are expressed, only AtFLS1 encodes a catalytically competent protein. AtFLS1 also appears to be the only member of this group that influences flavonoid levels and the root gravitropic response in seedlings under nonstressed conditions. This study showed that the other expressed AtFLS sequences have tissue- and cell type-specific promoter activities that overlap with those of AtFLS1 and encode proteins that interact with other flavonoid enzymes in yeast two-hybrid assays. Thus, it is possible that these "pseudogenes" have alternative, noncatalytic functions that have not yet been uncovered.