Tikhonova Evgeniya, Mariasina Sofia, Arkova Olga, Maksimenko Oksana, Georgiev Pavel, Bonchuk Artem
Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia.
Center for Magnetic Tomography and Spectroscopy, Faculty of Fundamental Medicine, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia.
Int J Mol Sci. 2022 Mar 31;23(7):3862. doi: 10.3390/ijms23073862.
In , CLAMP is an essential zinc-finger transcription factor that is involved in chromosome architecture and functions as an adaptor for the dosage compensation complex. Most of the known architectural proteins have structural N-terminal homodimerization domains that facilitate distance interactions. Because CLAMP performs architectural functions, we tested its N-terminal region for the presence of a homodimerization domain. We used a yeast two-hybrid assay and biochemical studies to demonstrate that the adjacent N-terminal region between 46 and 86 amino acids is capable of forming homodimers. This region is conserved in CLAMP orthologs from most insects, except Hymenopterans. Biophysical techniques, including nuclear magnetic resonance (NMR) and small-angle X-ray scattering (SAXS), suggested that this domain lacks secondary structure and has features of intrinsically disordered regions despite the fact that the protein structure prediction algorithms suggested the presence of beta-sheets. The dimerization domain is essential for CLAMP functions in vivo because its deletion results in lethality. Thus, CLAMP is the second architectural protein after CTCF that contains an unstructured N-terminal dimerization domain.
在[具体物种]中，CLAMP是一种重要的锌指转录因子，参与染色体结构构建，并作为剂量补偿复合体的衔接子发挥作用。大多数已知的染色体结构蛋白都具有结构性的N端同源二聚化结构域，有助于远距离相互作用。由于CLAMP具有染色体结构构建功能，我们检测了其N端区域是否存在同源二聚化结构域。我们利用酵母双杂交试验和生化研究来证明，46至86个氨基酸之间相邻的N端区域能够形成同源二聚体。除膜翅目昆虫外，该区域在大多数昆虫的CLAMP直系同源物中是保守的。包括核磁共振（NMR）和小角X射线散射（SAXS）在内的生物物理技术表明，尽管蛋白质结构预测算法提示存在β折叠，但该结构域缺乏二级结构，具有内在无序区域的特征。二聚化结构域对于CLAMP在体内的功能至关重要，因为其缺失会导致致死性。因此，CLAMP是继CTCF之后第二种含有无结构N端二聚化结构域的染色体结构蛋白。
