Nucleotide-Dependent Conformational Changes and Assembly of the AAA ATPase SKD1/VPS4B
Nucleotide-Dependent Conformational Changes and Assembly of the AAA ATPase SKD1/VPS4B
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DOI：
10.1111/j.1600-0854.2008.00831.x
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发表时间：
2008-12-01
期刊：
影响因子：
4.5
通讯作者：
Kawasaki, Masato
中科院分区：
文献类型：
--
作者：
Inoue, Michio;Kamikubo, Hironari;Kawasaki, Masato
SKD1/VPS4B属于与多种细胞活动相关的腺苷三磷酸酶（AAA）家族，并调节多泡体（MVB）的生物发生。SKD1在atp酶周期中改变其寡聚体状态，随后在MVBs形成过程中从内体释放运输所需的内体分选复合物（ESCRT）复合物。在本研究中，我们描述了单体SKD1中ATP和ADP结合的结构域运动。核苷酸结合在SKD1的α / β和α -螺旋结构域之间，诱导类似于20度的结构域旋转和结合位点的关闭，这与AAA+ atp酶HslU中观察到的变化相似。凝胶过滤和小角度x射线散射实验表明，SKD1的atp结合形式在溶液中寡聚，而SKD1的ADP结合形式和载脂蛋白形式作为单体存在，尽管ADP和atp结合形式的构象几乎相同。核苷酸结合的SKD1结构与六聚体环排列相容，类似于AAA atp酶p97 D1环。在SKD1的六聚环模型中，来自邻近分子的Arg290与ATP的γ -磷酸结合，促进ATP结合形式的低聚化。ATP水解会消除这种相互作用，随后的核苷酸释放导致结构域旋转，这共同导致SKD1低聚物的分解。
SKD1/VPS4B belongs to the adenosine triphosphatases associated with diverse cellular activities (AAA) family and regulates multivesicular body (MVB) biogenesis. SKD1 changes its oligomeric state during the ATPase cycle and subsequently releases endosomal sorting complex required for transport (ESCRT) complexes from endosomes during the formation of MVBs. In this study, we describe domain motions in monomeric SKD1 on ATP and ADP binding. Nucleotides bind between the alpha/beta and the alpha-helical domains of SKD1, inducing a similar to 20 degrees domain rotation and closure of the binding site, which are similar to the changes observed in the AAA+ ATPase, HslU. Gel filtration and small-angle X-ray scattering experiments showed that the ATP-bound form of SKD1 oligomerizes in solution, whereas ADP-bound and apo forms of SKD1 exist as monomers, even though the conformations of the ADP- and ATP-bound forms are nearly identical. Nucleotide-bound SKD1 structures are compatible with a hexameric ring arrangement reminiscent of the AAA ATPase p97 D1 ring. In the hexameric ring model of SKD1, Arg290 from a neighboring molecule binds to the gamma-phosphate of ATP, which promotes oligomerization of the ATP-bound form. ATP hydrolysis would eliminate this interaction and subsequent nucleotide release causes the domains to rotate, which together lead to the disassembly of the SKD1 oligomer.