Kurimoto Kazuki, Kuwasako Kanako, Sandercock Alan M, Unzai Satoru, Robinson Carol V, Muto Yutaka, Yokoyama Shigeyuki
RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan.
Proteins. 2009 May 1;75(2):360-72. doi: 10.1002/prot.22246.
The human AU RNA binding protein/enoyl-Coenzyme A hydratase (AUH) is a 3-hydroxy-3-methylglutaconyl-CoA dehydratase in the leucine degradation pathway. It also possesses an RNA-binding activity to AUUU repeats, which involves no known conserved RNA-binding domains and is seemingly unrelated to the enzymatic activity. In this study, we performed mass spectrometric analyses to elucidate the oligomeric states of AUH in the presence and absence of RNA. With a short RNA (AUUU) or without RNA, AUH mainly exists as a trimer in solution. On the other hand, the AUH trimer dimerizes upon binding to one molecule of a long RNA containing 24 repeats of the AUUU motif, (AUUU)(24)A. AUH was crystallized with the long RNA. Although the RNA was disordered in the crystalline lattice, the AUH structure was determined as an asymmetric dimer of trimers with a kink in the alignment of the trimer axes, resulting in the formation of two clefts with significantly different sizes.
人类AU RNA结合蛋白/烯酰辅酶A水合酶（AUH）是亮氨酸降解途径中的一种3-羟基-3-甲基戊二酰辅酶A脱水酶。它还具有与AUUU重复序列的RNA结合活性，该活性不涉及已知的保守RNA结合结构域，且似乎与酶活性无关。在本研究中，我们进行了质谱分析，以阐明在有RNA和无RNA的情况下AUH的寡聚状态。在存在短RNA（AUUU）或无RNA的情况下，AUH在溶液中主要以三聚体形式存在。另一方面，AUH三聚体在与一分子含有24个AUUU基序重复序列（AUUU）(24)A的长RNA结合时会二聚化。AUH与长RNA一起结晶。尽管RNA在晶格中无序，但AUH的结构被确定为三聚体的不对称二聚体，三聚体轴的排列有一个扭结，导致形成两个大小显著不同的裂隙。
