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Allelic Analyses of the Arabidopsis YUC1 Locus Reveal Residues and Domains Essential for the Functions of YUC Family of Flavin Monooxygenases
Author(s) -
Hou Xianhui,
Liu Sainan,
Pierri Florencia,
Dai Xinhua,
Qu LiJia,
Zhao Yunde
Publication year - 2011
Publication title -
journal of integrative plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.734
H-Index - 83
eISSN - 1744-7909
pISSN - 1672-9072
DOI - 10.1111/j.1744-7909.2010.01007.x
Subject(s) - mutant , biology , arabidopsis , monooxygenase , flavin adenine dinucleotide , biochemistry , flavin group , cofactor , genetics , nicotinamide adenine dinucleotide phosphate , gene , enzyme , cytochrome p450 , oxidase test
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.