The Cloning And Expression Of Gene Steroleosin Of Brassica Napus

Steroleosin is a sterol-binding dehydrogenase in seed oil bodies, these two homologous proteins tentatively named steroleosin-A and steroleosin-B is distinguished by their molecular weight. We have summit the sequence of these gene steroleosin-A and steroleosin-B mRNA in Brassic napus into genebank, their accession number is EF198071 and DQ648784.These two genes have 1224 and 1608 basepair, both have include complete CDS and also 3'-untranslated region. The ORF of steroleosin-A have 1047bp from 43 to 1092, the steroleosin-B is 1386bp from 83 to 1468, so the protein they coded are 349 and 461 amino acid residues.The corresponding genomic sequence (1808 nucleotides) of this putative steroleosin-A gene was also obtained by PCR cloning (accession no. EF473268 in GenBank). Rape genomic sequence of steroleosin-A gene comprises six exons with five introns conservatively inserted in their coding regions. The splicing model of introns accords with the GT/AG rule in Eukaryotes.Steroleosin protein landed GenBand with accession no. ABM90633 and AAM46847 is a kind of protein associated with rapeseed oil bodies. The deduced polypeptide of the rape clone comprises 349 amino acid residues of Mr 39kDa and PI 6.06 and 461 amino acid residues of Mr 51kDa and PI 6.29 with all commonly kinds of amino acid include. The similarity of these two steroleosin is 43% and they both belong to SDR family.Steroleosin-A expression are expressed in a spatially co-cordinated and temporally regulated manner and appears to be highly regulated through embryogenesis. RT-PCR demonstrated that steroleosin-A mRNA was detected in the earliest embryos, even in the petal, and also present in maturing rapeseeds. Steroleosin-A expression increased dramatically in the latter stages of embryogenesis, and this mRNA maintained a substantial level thereafter until the rapeseeds started to desiccate in a mode similar to oleosin mRNA. It is presumably revealed that the steroleosin-A gene is transcribed along with oleosin and caleosin genes during seed maturation when oil bodies are actively assembled in diverse species. Steroleosin-A was detected in cotyledon root and stem impermanently of budding seed. Steroleosin-A gene was transcribed in cotyledon in 2-10 days after imbibitions and the 4d is the most. The transcribe is weaken later.also transcribe in stem of 4-6 DAI and root of 2 DAI.