摘要
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 yucl yuc4 double mutants. Among the isolated mutants, five of them contained mutations in the YUC1 gene. Interestingly, the mutations identified in the new yucl 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 Ser139 to Phe conversion in yucl, a mutation that is located between the two nucleotide-binding sites. By analyzing a series of yucl mutants, we identified key residues and motifs essential for the functions of YUC1 FMO.
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 yucl yuc4 double mutants. Among the isolated mutants, five of them contained mutations in the YUC1 gene. Interestingly, the mutations identified in the new yucl 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 Ser139 to Phe conversion in yucl, a mutation that is located between the two nucleotide-binding sites. By analyzing a series of yucl mutants, we identified key residues and motifs essential for the functions of YUC1 FMO.
基金
supported by the National Natural Science Foundation of China (No. 30628012 to Y.Z and 30625002 to L.-J.Q)
National Institutes of Health (R01GM68631 to Y.Z.)
supported by a scholarship from the China Scholarship Council
