Disease relevance of ETR1

• To study the link between FAS and cell respiration further, we also created a yeast strain that has FabI enoyl-ACP (acyl-carrier protein) reductase gene from Escherichia coli engineered to carry a mitochondrial targeting sequence in the genome, replacing the endogenous ETR1 gene [1].

High impact information on ETR1

• Saturable binding sites for [14C]ethylene were detected in transgenic yeast expressing the ETR1 protein, whereas control yeast lacking ETR1 showed no detectable ethylene binding [2].
• Yeast expressing a mutant form of ETR1 (etr1-1) also showed no detectable ethylene binding, which provides an explanation for the ethylene-insensitive phenotype observed in plants carrying this mutation [2].
• Mutations in the ETR1 gene of Arabidopsis thaliana confer insensitivity to ethylene, which indicates a role for the gene product in ethylene signal transduction [2].
• Starting with markers flanking the self-incompatibility genes in Brassica, we identified the homeologous region in Arabidopsis as a previously uncharacterized segment of chromosome 1 in the immediate vicinity of the ethylene response gene ETR1 [3].
• Triclosan that is used as an antibacterial agent against fatty acid synthesis type II 2-enoyl thioester reductases inhibited growth of FabI overexpressing mutant yeast cells but was not able to inhibit respiratory growth of the ETR2- or ETR1-complemented mutant yeast cells [4].

Biological context of ETR1

• The 5'- and 3'-flanking (coding) regions of ETR2 and ETR1 are about 90% (97%) identical, indicating that the genes have evolved via gene duplication [4].
• Identification of an ethylene-dependent phenotype for a loss-of-function receptor mutant gave a unique opportunity for genetic and biochemical analysis of upstream events in ethylene signaling, including demonstration that the dominant ethylene-insensitive phenotype of etr2-1 is partially dependent on ETR1 [5].
• Mutagenesis of Tyr73 in Mrf1p, corresponding to Tyr79 in Etr1p, produced similar results [6].

Anatomical context of ETR1

• Analysis of two of these genes that have been cloned reveals that ethylene signalling involves a combination of a protein (ETR1) with similarity to bacterial histidine kinases and a protein (CTR1) with similarity to Raf-1, a protein kinase involved in multiple signalling cascades in eukaryotic cells [7].
• In a mrf1 null mutant the absorption spectra of cytochromes b, a, and a3 were undetectable, although mitochondrial DNA and protein synthesis in mitochondria were intact [8].
• Our data indicate that the mitochondrial reductase activity is indispensable for respiratory function in yeast, emphasizing the significance of Mrf1p (Etr1p) and mitochondrial FAS for the integrity of the respiratory competent organelle [6].

Associations of ETR1 with chemical compounds

• Like the situation with ETR1, expression of ETR2 in respiration-deficient Saccharomyces cerevisiae mutant cells devoid of Ybr026p/Etr1p was able to restore growth on glycerol [4].
• Candida tropicalis enoyl thioester reductase Etr1p and the Saccharomyces cerevisiae homologue Mrf1p catalyse the NADPH-dependent reduction of trans-2-enoyl thioesters in mitochondrial fatty acid synthesis (FAS) [6].

Analytical, diagnostic and therapeutic context of ETR1

• Quantitative PCR analysis and reverse transcriptase-PCR indicated that both genes were expressed about equally in fermenting and ETR1 predominantly respiring yeast cells [4].
• Etr1p (enoyl thioester reductase) was identified via purification of the protein followed by molecular cloning [1].

References