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PMID:19682296

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Citation

Schilmiller, AL, Stout, J, Weng, JK, Humphreys, J, Ruegger, MO and Chapple, C (2009) Mutations in the cinnamate 4-hydroxylase gene impact metabolism, growth and development in Arabidopsis. Plant J. 60:771-82

Abstract

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.

Links

PubMed Online version:10.1111/j.1365-313X.2009.03996.x

Keywords

Arabidopsis/enzymology; Arabidopsis/genetics; Arabidopsis/growth & development; Arabidopsis Proteins/chemistry; Arabidopsis Proteins/genetics; Arabidopsis Proteins/physiology; Chromosome Mapping; Escherichia coli/genetics; Fertility/genetics; Lignin/metabolism; Malates/metabolism; Mutation, Missense; Pollen/enzymology; Pollen/genetics; Pollen/growth & development; Protein Folding; Trans-Cinnamate 4-Monooxygenase/chemistry; Trans-Cinnamate 4-Monooxygenase/genetics; Trans-Cinnamate 4-Monooxygenase/physiology

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

ARATH:TCMO

acts_upstream_of_or_within

GO:0009555: pollen development

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:TCMO

acts_upstream_of_or_within

GO:0009698: phenylpropanoid metabolic process

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:TCMO

acts_upstream_of_or_within

GO:0009808: lignin metabolic process

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:TCMO

acts_upstream_of_or_within

GO:0032502: developmental process

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete


See also

References

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