Gong L, Millas S, Maul G G, Yeh E T
Research Center for Cardiovascular Diseases, Institute of Molecular Medicine for the Prevention of Human Diseases, Division of Molecular Medicine, The University of Texas-Houston Health Science, Houston, USA.
J Biol Chem. 2000 Feb 4;275(5):3355-9. doi: 10.1074/jbc.275.5.3355.
Sentrin-1, also called SUMO-1, is a protein of 101 residues that is distantly related to ubiquitin and another ubiquitin-like protein, NEDD8. Here we report the cloning of a novel sentrin-specific protease, SENP1, which has no homology to the known de-ubiquitinating enzymes or ubiquitin C-terminal hydrolases. However, SENP1 is distantly related to the yeast Smt3-specific protease, Ulp1. A COS cell expression system was used to demonstrate the activity of SENP1 in vivo. When HA-tagged sentrin-1 was co-expressed with SENP1, the higher molecular weight sentrin-1 conjugates were completely removed. Surprisingly, the major sentrinized band at 90 kDa remained intact. The disappearance of the high molecular weight sentrin-1 conjugates also coincided with an increase in free sentrin-1 monomers. SENP1 is also active against proteins modified by sentrin-2, but not those modified by ubiquitin or NEDD8. In addition, sentrinized PML, a tumor suppressor protein that resides in the nucleus, was selectively affected by SENP1, whereas sentrinized RanGAP1, which is associated with the cytoplasmic fibrils of the nuclear pore complex, remained intact. The inability of SENP1 to process sentrinized RanGAP1 in vivo is most likely due to its nuclear localization because SENP1 is active against sentrinized RanGAP1 in vitro. The identification of a nuclear-localized, sentrin-specific protease will provide a unique tool to study the role of sentrinization in the biological function of PML and in the pathogenesis of acute promyelocytic leukemia.
Sentrin-1，也称为SUMO-1，是一种由101个氨基酸残基组成的蛋白质，与泛素以及另一种类泛素蛋白NEDD8有较远的亲缘关系。在此我们报告一种新型Sentrin特异性蛋白酶SENP1的克隆，它与已知的去泛素化酶或泛素C末端水解酶没有同源性。然而，SENP1与酵母Smt3特异性蛋白酶Ulp1有较远的亲缘关系。利用COS细胞表达系统在体内证实了SENP1的活性。当带有HA标签的Sentrin-1与SENP1共表达时，高分子量的Sentrin-1缀合物被完全去除。令人惊讶的是，90 kDa处的主要Sentrin化条带保持完整。高分子量Sentrin-1缀合物的消失也与游离Sentrin-1单体的增加相一致。SENP1对Sentrin-2修饰的蛋白质也有活性，但对泛素或NEDD8修饰的蛋白质无活性。此外，位于细胞核中的肿瘤抑制蛋白Sentrin化的PML受到SENP1的选择性影响，而与核孔复合体细胞质纤维相关的Sentrin化RanGAP1保持完整。SENP1在体内无法处理Sentrin化的RanGAP1很可能是由于其核定位，因为SENP1在体外对Sentrin化的RanGAP1有活性。鉴定一种核定位的Sentrin特异性蛋白酶将为研究Sentrin化在PML生物学功能及急性早幼粒细胞白血病发病机制中的作用提供一个独特的工具。
