EUKARYOTIC METHIONYL AMINOPEPTIDASES - 2 CLASSES OF COBALT-DEPENDENT ENZYMES
EUKARYOTIC METHIONYL AMINOPEPTIDASES - 2 CLASSES OF COBALT-DEPENDENT ENZYMES
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DOI：
10.1073/pnas.92.17.7714
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发表时间：
1995-08-15
影响因子：
11.1
通讯作者：
BRADSHAW, RA
中科院分区：
文献类型：
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作者：
ARFIN, SM;KENDALL, RL;BRADSHAW, RA
使用来源于猪甲硫氨酰氨基肽酶（MetAP;甲硫氨酰氨基肽酶，肽酶M; EC 3.4.11.18）的部分氨基酸序列数据，获得了同源人酶的全长克隆。该cDNA序列含有2569个核苷酸，具有一个开放阅读框，对应于478个氨基酸的蛋白质。代表催化结构域的C-末端部分显示与来自各种原核生物和酵母的MetAP序列的有限同一性，而N末端富含带电氨基酸，包括碱性和酸性残基的延伸串。这些高度极性的延伸可能导致观察到的虚假的高分子量（67 kDa）。该cDNA序列与称为p67的大鼠蛋白高度相似，p67被鉴定为起始因子eIF 2 α磷酸化的抑制剂，并且先前基于有限的序列同源性预测为金属肽酶。模型构建建立了人MetAP（p67）可以容易地容纳到大肠杆菌MetAP结构中，并且Co2+配体被完全保留。然而，发现人MetAP更类似于酵母开放阅读框架，其与先前报道的酵母MetAP显著不同。来自Methanothermus fervidus的类似部分序列表明，这种p67样序列也存在于原核生物中。这些发现表明，存在两个钴依赖性MetAP家族，目前由原核生物和酵母序列组成（并由E. coli结构）（I型），另一方面是人MetAP、酵母开放阅读框架和部分原核序列（II型）。
Using partial amino acid sequence data derived from porcine methionyl aminopeptidase (MetAP; methionine aminopeptidase, peptidase M; EC 3.4.11.18), a full-length clone of the homologous human enzyme has been obtained. The cDNA sequence contains 2569 nt with a single open reading frame corresponding to a protein of 478 amino acids. The C-terminal portion representing the catalytic domain shows limited identity with MetAP sequences from various prokaryotes and yeast, while the N terminus is rich in charged amino acids, including extended strings of basic and acidic residues. These highly polar stretches likely result in the spuriously high observed molecular mass (67 kDa). This cDNA sequence is highly similar to a rat protein, termed p67, which was identified as an inhibitor of phosphorylation of initiation factor eIF2 alpha and was previously predicted to be a metallopeptidase based on limited sequence homology. Model building established that human MetAP (p67) could be readily accommodated into the Escherichia coli MetAP structure and that the Co2+ ligands were fully preserved. However, human MetAP was found to be much more similar to a yeast open reading frame that differed markedly from the previously reported yeast MetAP. A similar partial sequence from Methanothermus fervidus suggests that this p67-like sequence is also found in prokaryotes. These findings suggest that there are two cobalt-dependent MetAP families, presently composed of the prokaryote and yeast sequences (and represented by the E. coli structure) (type I), on the one hand, and by human MetAP, the yeast open reading Frame, and the partial prokaryotic sequence (type II), on the other.