Bradshaw R E, Dixon S W, Raitt D C, Pillar T M
Leicester Biocentre, University of Leicester, UK.
Curr Genet. 1993 May-Jun;23(5-6):501-7. doi: 10.1007/BF00312642.
The structural gene for 5-aminolevulinate (ALA) synthase has been cloned and sequenced from the filamentous fungus Aspergillus nidulans using an oligonucleotide probe based on a highly conserved-amino-acid sequence found in ALA synthase genes of a wide range of species. The cloned gene, hemA, has a 5' untranslated mRNA of 92 nucleotides (nt) and one intron (64 nt). The deduced protein sequence (648 amino acids) shows 64% identity to the yeast ALA synthase in the C-terminal region of 453 amino acids. The N-terminal region is typical of ALA synthase proteins in that the specific amino-acid sequence is not conserved but consists of a "leader" region rich in basic amino acids, believed to be involved in mitochondrial targeting, followed by a stretch of largely hydrophobic residues which may allow interaction with the inner mitochondrial membrane. Under the conditions used the transcription of hemA was unaffected by dextrose repression, heat shock, or oxygen levels.
利用基于在多种物种的δ-氨基-γ-酮戊酸（ALA）合酶基因中发现的高度保守氨基酸序列的寡核苷酸探针，从丝状真菌构巢曲霉中克隆并测序了ALA合酶的结构基因。克隆的基因hemA有一段92个核苷酸（nt）的5'非翻译mRNA和一个内含子（64 nt）。推导的蛋白质序列（648个氨基酸）在453个氨基酸的C末端区域与酵母ALA合酶显示出64%的同一性。N末端区域是ALA合酶蛋白的典型特征，即特定的氨基酸序列不保守，而是由富含碱性氨基酸的“前导”区域组成，据信该区域参与线粒体靶向，随后是一段主要为疏水残基的序列，这可能允许与线粒体内膜相互作用。在所使用的条件下，hemA的转录不受葡萄糖阻遏、热休克或氧气水平的影响。
