苯丙素
生物
拟南芥
突变体
生物化学
基因
次生代谢
遗传学
酶
生物合成
作者
Anthony L. Schilmiller,Jake Stout,Jing‐Ke Weng,John F. Humphreys,Max O. Ruegger,Clint Chapple
出处
期刊:Plant Journal
[Wiley]
日期:2009-11-25
卷期号:60 (5): 771-782
被引量:259
标识
DOI:10.1111/j.1365-313x.2009.03996.x
摘要
The initial reactions of the phenylpropanoid pathway convert phenylalanine to p-coumaroyl CoA, a branch point metabolite from which many phenylpropanoids are made. Although the second enzyme of this pathway, cinnamic acid 4-hydroxylase (C4H), is well characterized, a mutant for the gene encoding this enzyme has not yet, to our knowledge, been identified, presumably because knock-out mutations in this gene would have severe phenotypes. This work describes the characterization of an allelic series of Arabidopsis reduced epidermal fluorescence 3 (ref3) mutants, each of which harbor mis-sense mutations in C4H (At2g30490). Heterologous expression of the mutant proteins in Escherichia coli yields enzymes that exhibit P420 spectra, indicative of mis-folded proteins, or have limited ability to bind substrate, indicating that the mutations we have identified affect protein stability and/or enzyme function. In agreement with the early position of C4H in phenylpropanoid metabolism, ref3 mutant plants accumulate decreased levels of several different classes of phenylpropanoid end-products, and exhibit reduced lignin deposition and altered lignin monomer content. Furthermore, these plants accumulate a novel hydroxycinnamic ester, cinnamoylmalate, which is not found in the wild type. The decreased C4H activity in ref3 also causes pleiotropic phenotypes, including dwarfism, male sterility and the development of swellings at branch junctions. Together, these observations indicate that C4H function is critical to the normal biochemistry and development of Arabidopsis.
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