시베리아 철갑상어(Acipenser baerii) gulono-gamma-lactone oxidase (GULO)의 유전자 구조 및 발현특징

Abstract

Genomic structure and full-length cDNA of gulonolactone oxidase (GULO), a key enzyme for ascorbic acid biosynthesis were characterized in Siberian sturgeon (Acipenser baerii). Sturgeon GULO gene consists of twelve exons interrupted by 11 introns with the conserved gt/ag rule in the exon-intron boundary regions. Deduced amino acid sequence represents highly conserved motifs in both FAD binding domain and ALO domain. Molecular phylogeny of GULO gene revealed that vertebrate GULO genes formed a monophyletic group and clustered in the pattern which is in accordance with known taxonomic appraisal. Various putative binding sites of transcription factors were predicted on the GULO gene promoter region. They included several stress-response and/or detoxification process such as HSF, CREB, AhR and AP1. In particular, HFH-3 and Gfi-1 were also predicted which have been proposed to serve as the potential transcription factors to regulate kidney-specific gene expression in mouse uromodulin promoter to target production of recombinant proteins into urine of transgenic animals. Tissue distribution of Siberian sturgeon GULO mRNA was kidney-predominant but a weak expression was also detectable in a few tissues. Such minor expression was found in the brain, intestine, liver and muscle. During embryonic development GULO mRNA expression began to appear at the time of rudimentary heart formation and significantly reduced expression was observed after the beginning of exogenous feeding. Potential modulation of GULO gene expression was examined by using RT-PCR in response to heat shock, dietary hormone administration and bacterial challenge. As a result, their possible effects on the modulated transcription of GULO gene toward up-regulation were examined.