The molecular basis of malonyl-CoA decarboxylase deficiency
The molecular basis of malonyl-CoA decarboxylase deficiency
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DOI：
10.1086/302492
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发表时间：
1999-08-01
影响因子：
9.8
通讯作者：
Christodoulou, L
中科院分区：
文献类型：
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作者：
FitzPatrick, DR;Hill, A;Christodoulou, L
我们鉴定了一个2.1 kb的人cDNA，其开放阅读框为1362 bp（454个氨基酸），与鹅丙二酰辅酶A脱羧酶（MCD）的氨基酸同源性为70.3%。我们已经确定了两个不同的纯合突变，在人类MCD（MCD）通过使用RT-PCR分析成纤维细胞RNA从两个先前报道的血缘苏格兰患者MCD缺乏症。第一个突变是442 C->G颠换，导致蛋白质N-末端一半中的提前终止密码子（S148 X）。第二个是在成熟RNA中插入13-bp，导致预测的蛋白质截短的移码。这种插入是内含子突变产生新的剪接受体序列（IVS 4 - 14 Ad-->G）的结果。这两种突变被发现在家庭中适当地分离，并且在100个正常的无关个体中没有发现。预测这些突变会导致MCD缺陷，从而确认该转录本为hMCD直系同源物。hMCD的肽序列显示C-末端过氧化物酶体靶向序列（-SKL）。这种靶向信号似乎在体内起作用，因为MCD酶活性在大鼠肝匀浆中的分布-通过亚细胞分级测定-强烈表明MCD除了在别处报告的线粒体定位外，还定位于过氧化物酶体。这些数据强烈支持该cDNA编码人MCD，一种重要的脂肪酸代谢调节因子。
We characterized a 2.1-kb human cDNA with a 1362-bp (454-amino acid) open reading frame showing 70.3% amino acid identity to goose malonyl-CoA decarboxylase (MCD). We have identified two different homozygous mutations in human MCD (MCD) by using RT-PCR analysis of fibroblast RNA from two previously reported consanguineous Scottish patients with MCD deficiency. The first mutation is a 442C-->G transversion resulting in a premature stop codon (S148X) in the N-terminal half of the protein. The second is a 13-bp insertion in the mature RNA, causing a frameshift with predicted protein truncation. This insertion is the result of an intronic mutation generating a novel splice acceptor sequence (IVS4-14Ad-->G). Both mutations were found to segregate appropriately within the families and were not found in 100 normal unrelated individuals. These mutations would be predicted to cause MCD deficiency, thus confirming this transcript as the hMCD ortholog. The peptide sequence of hMCD revealed a C-terminal peroxisomal targeting sequence (-SKL). This targeting signal appears to be functional in vivo, since the distribution of MCD enzymatic activity in rat liver homogenates-as measured by means of subcellular fractionation-strongly suggests that MCD is localized to peroxisomes in addition to the mitochondrial localization reported elsewhere. These data strongly support this cDNA as encoding human MCD, an important regulator of fatty acid metabolism.