Two anthranilate synthase genes in Arabidopsis: defense-related regulation of the tryptophan pathway.
AUTOR(ES)
Niyogi, K K
RESUMO
Arabidopsis thaliana has two genes, ASA1 and ASA2, encoding the alpha subunit of anthranilate synthase, the enzyme catalyzing the first reaction in the tryptophan biosynthetic pathway. As a branchpoint enzyme in aromatic amino acid biosynthesis, anthranilate synthase has an important regulatory role. The sequences of the plant genes are homologous to their microbial counterparts. Both predicted proteins have putative chloroplast transit peptides at their amino termini and conserved amino acids involved in feedback inhibition by tryptophan. ASA1 and ASA2 cDNAs complement anthranilate synthase alpha subunit mutations in the yeast Saccharomyces cerevisiae and in Escherichia coli, confirming that both genes encode functional anthranilate synthase proteins. The distributions of ASA1 and ASA2 mRNAs in various parts of Arabidopsis plants are overlapping but nonidentical, and ASA1 mRNA is approximately 10 times more abundant in whole plants. Whereas ASA2 is expressed at a constitutive basal level, ASA1 is induced by wounding and bacterial pathogen infiltration, suggesting a novel role for ASA1 in the production of tryptophan pathway metabolites as part of an Arabidopsis defense response. Regulation of key steps in aromatic amino acid biosynthesis in Arabidopsis appears to involve differential expression of duplicated genes.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=160168Documentos Relacionados
- Defense-related emotions in humans
- Tryptophan mutants in Arabidopsis: the consequences of duplicated tryptophan synthase beta genes.
- Use of Arabidopsis thaliana defense-related mutants to dissect the plant response to pathogens.
- Plant homeodomain protein involved in transcriptional regulation of a pathogen defense-related gene.
- Arabidopsis thaliana defense-related protein ELI3 is an aromatic alcohol:NADP+ oxidoreductase