Characterization of Citrus sinensis type 1 mitochondrial alternative oxidase

DAURELIO, L.D.; OTTADO, J.; ORELLANO, E.G.

Pinamar, Argentina.

Congreso; SAIB 41th Annual Meeting, SAN 20th Annual Meeting and PABMB 10th Congress.; 2005

Panamerican Association for Biochemistry and Molecular Biology

Mitochondrial alternative oxidase (AOX) is a quinol oxidase that catalizes cyanide-resistant reduction of O2 to water without translocation of protons. It is encoded by a nuclear gene family classified in two subfamilies: AOX1 and AOX2/3. AOX1 is known for its induction in biotic and abiotic stress stimuli. Our objective is to characterize the AOX type 1 in Citrus sinensis. Using a 440 bp region belonging to orange AOX1 as a probe, a Southern Blot with EcoRI enzyme was carried out. Two alleles (2.1 and 5.6 kbp) were detected. A sub-library was constructed using 2.1 kbp fragments in pBluescriptKS+ vector and screened with the same probe, detecting two positives clones which were sequenced. A 354 bp sequence belonged to promoter region and cis-acting elements were detected in-silico. The most relevant are TCA-Box (Salicilic Acid Response), WRKY (associated with pathogen defence), and PR-Box (Pathogen Response). The other 1749 bp completely cover the coding sequence (four exons and three introns), 5’UTR, and part of 3’UTR. Two highly conserved cysteine residues which are involved in homo-dimerization by S-S bond formation and two regions EXXH corresponding to the active site were found. Phylogenetic tree grouped AOX clone with dicots AOX1. C. sinensis may posses two AOX1 alleles, being one of them characterized. Its putative stress participation will be analyzed.