Suzuki H, Seki M, Kobayashi T, Kaneko H, Kondo N, Harata M, Mizuno S, Masuko T, Enomoto T
Molecular Cell Biology Laboratory, Tohoku University, Sendai, Miyagi, 980-8578, Japan.
Biochem Biophys Res Commun. 2001 Aug 17;286(2):322-7. doi: 10.1006/bbrc.2001.5387.
Bloom Syndrome (BS) is a human autosomal genetic disorder characterized by a predisposition to a variety of malignant tumors. The gene responsible for BS encodes a protein (BLM) consisting of 1417 amino acids with a nuclear localization signal in the C-terminal region, which is a member of the RecQ helicase family. We previously showed, using a yeast two-hybrid system, that BLM interacted with Ubc9, which is the conjugating enzyme of SUMO-1 (small ubiquitin-related modifier-1). In the present study, we exogenously expressed a green fluorescent protein-tagged Bloom syndrome protein, GFP-BLM, in human 293EBNA cells and found that it formed dots/rod-like structures associated with SUMO-1 in the nucleus. Deletion experiments indicated that the region from amino acids 238 to 586 of BLM is required for the formation of dots/rod-like structures associated with SUMO-1, and the DNA helicase domain, but not the helicase activity itself, slightly affected the formation and/or stability of these structures. Expression of a GFP-BLM which contained the 238-586 region, but lacked the C-terminal nuclear localization signal, resulted in localization to the cytoplasm without the formation of dots/rod-like structures and association with SUMO-1, indicating that these events occur only in the nucleus.
布卢姆综合征（BS）是一种人类常染色体遗传病，其特征是易患多种恶性肿瘤。导致BS的基因编码一种由1417个氨基酸组成的蛋白质（BLM），在C端区域有一个核定位信号，它是RecQ解旋酶家族的成员。我们之前使用酵母双杂交系统表明，BLM与Ubc9相互作用，Ubc9是SUMO-1（小泛素相关修饰物-1）的缀合酶。在本研究中，我们在人293EBNA细胞中外源表达了绿色荧光蛋白标记的布卢姆综合征蛋白GFP-BLM，发现它在细胞核中形成了与SUMO-1相关的点状/棒状结构。缺失实验表明，BLM的238至586位氨基酸区域是形成与SUMO-1相关的点状/棒状结构所必需的，DNA解旋酶结构域而非解旋酶活性本身对这些结构的形成和/或稳定性有轻微影响。表达包含238 - 586区域但缺乏C端核定位信号的GFP-BLM，导致其定位于细胞质，不形成点状/棒状结构且不与SUMO-1结合，表明这些事件仅发生在细胞核中。
