title: Allelic analyses of the Arabidopsis YUC1 locus reveal residues and domains essential for the functions of YUC family of flavin monooxygenases.
abstract: Flavin monooxygenases (FMOs) play critical roles in plant growth and development by synthesizing auxin and other signaling molecules. However, the structure and function relationship within plant FMOs is not understood. Here we defined the important residues and domains of the Arabidopsis YUC1 FMO, a key enzyme in auxin biosynthesis. We previously showed that simultaneous inactivation of YUC1 and its homologue YUC4 caused severe defects in vascular and floral development. We mutagenized the yuc4 mutant and screened for mutants with phenotypes similar to those of yuc1 yuc4 double mutants. Among the isolated mutants, five of them contained mutations in the YUC1 gene. Interestingly, the mutations identified in the new yuc1 alleles were concentrated in the two GXGXXG motifs that are highly conserved among the plant FMOs. One such motif presumably binds to flavin adenine dinucleotide (FAD) cofactor and the other binds to nicotinamide adenine dinucleotide phosphate (NADPH). We also identified the Ser(139) to Phe conversion in yuc1, a mutation that is located between the two nucleotide-binding sites. By analyzing a series of yuc1 mutants, we identified key residues and motifs essential for the functions of YUC1 FMO.
authors.affiliation: National Laboratory for Protein Engineering and Plant Genetic Engineering, Peking-Yale Joint Research Center for Plant Molecular Genetics and AgroBiotechnology, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Xianhui
authors.initials: X
authors.lastname: Hou
authors.forename: Sainan
authors.initials: S
authors.lastname: Liu
authors.forename: Florencia
authors.initials: F
authors.lastname: Pierri
authors.forename: Xinhua
authors.initials: X
authors.lastname: Dai
authors.forename: Li-Jia
authors.initials: LJ
authors.lastname: Qu
authors.forename: Yunde
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000483:Alleles; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018548:Cotyledon / Q000254:growth & development; D004742:Enhancer Elements, Genetic; D035264:Flowers / Q000254:growth & development; D008969:Molecular Sequence Data; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D058526:Plant Vascular Bundle / Q000254:growth & development; D017354:Point Mutation; D013329:Structure-Activity Relationship
chemical_list: D029681:Arabidopsis Proteins; D010105:Oxygenases; C422746:YUC protein, Arabidopsis