Meyer K, Cusumano J C, Somerville C, Chapple C C
Department of Biochemistry, Purdue University, West Lafayette, IN 47907-1153, USA.
Proc Natl Acad Sci U S A. 1996 Jul 9;93(14):6869-74. doi: 10.1073/pnas.93.14.6869.
The fah1 mutant of Arabidopsis is defective in the accumulation of sinapic acid-derived metabolites, including the guaiacyl-syringyl lignin typical of angiosperms. Earlier results indicated that the FAH1 locus encodes ferulate-5-hydroxylase (F5H), a cytochrome P450-dependent monooxygenase (P450) of the general phenylpropanoid pathway. We have cloned the gene encoding this P450 by T-DNA tagging and have confirmed the identity of the cloned gene by complementation of the mutant phenotype. F5H shows 34% amino acid sequence identity with the avocado ripening-induced P450 CYP71A1 and 32% identity with the flavonoid-3',5'-hydroxylases of Petunia hybrida. In contrast, it shares much less homology with cinnamate-4-hydroxylase, a P450 that catalyzes the hydroxylation of cinnamic acid three steps earlier in the general phenylpropanoid pathway. Since the highest degree of identity between F5H and previously sequenced P450s is only 34%, F5H identifies a new P450 subfamily that has been designated CYP84.
拟南芥的fah1突变体在芥子酸衍生代谢产物的积累方面存在缺陷，这些代谢产物包括被子植物特有的愈创木基-紫丁香基木质素。早期结果表明，FAH1基因座编码阿魏酸-5-羟化酶（F5H），它是一般苯丙烷类途径中一种细胞色素P450依赖性单加氧酶（P450）。我们通过T-DNA标签克隆了编码这种P450的基因，并通过突变体表型的互补作用证实了克隆基因的身份。F5H与鳄梨成熟诱导的P450 CYP71A1的氨基酸序列同一性为34%，与矮牵牛的类黄酮-3'，5'-羟化酶的同一性为32%。相比之下，它与肉桂酸-4-羟化酶的同源性要低得多，肉桂酸-4-羟化酶是一种在一般苯丙烷类途径中比阿魏酸早三步催化肉桂酸羟基化的P450。由于F5H与先前测序的P450之间的最高同一性仅为34%，F5H确定了一个新的P450亚家族，已将其命名为CYP84。
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