Molecular recognition of the Tes LIM2-3 domains by the actin-related protein Arp7A.
Molecular recognition of the Tes LIM2-3 domains by the actin-related protein Arp7A.
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DOI：
10.1074/jbc.m110.171264
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发表时间：
2011-04-01
期刊：
影响因子：
--
通讯作者：
Way M
中科院分区：
文献类型：
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作者：
Boëda B;Knowles PP;Briggs DC;Murray-Rust J;Soriano E;Garvalov BK;McDonald NQ;Way M
肌动蛋白相关蛋白（Arps）是一个高度保守的蛋白质家族，与肌动蛋白具有广泛的序列和结构相似性。所有表征的Arps都是与染色质或细胞骨架相关的大的多聚体复合物的组分。此外，人类基因组编码五个保守的，但在很大程度上未表征的“孤儿”Arps，这似乎是大多数睾丸特异性。在这里，我们表明，Arp 7A，它有43%的序列同一性β-肌动蛋白，形成一个复合物与细胞骨架蛋白Tes和Mena在顶体下层的圆形精子细胞。Arp 7A的N-末端65个残基延伸到肌动蛋白样折叠直接与Tes相互作用。1- 65 Arp 7A·LIM 2 - 3 Tes·EVH 1 Mena复合物的晶体结构显示Arp 7A的28-49位残基与Tes的LIM 2 -3结构域接触。来自Arp 7A的两个丙氨酸残基占据两个LIM结构域中的等效非极性口袋以及结合LIM 2 -3连接的插入GPAK接头对于Arp 7A-Tes相互作用是关键的。在与不相关配体结合的LMO 4和Lhx 3的串联LIM结构域结构中也可以看到等效占据的非极性口袋。我们的研究结果表明，非极性口袋的相互作用是一个共同的特点串联LIM结构域的相互作用，但配体的特异性主要是由接头序列。
Actin-related proteins (Arps) are a highly conserved family of proteins that have extensive sequence and structural similarity to actin. All characterized Arps are components of large multimeric complexes associated with chromatin or the cytoskeleton. In addition, the human genome encodes five conserved but largely uncharacterized “orphan” Arps, which appear to be mostly testis-specific. Here we show that Arp7A, which has 43% sequence identity with β-actin, forms a complex with the cytoskeletal proteins Tes and Mena in the subacrosomal layer of round spermatids. The N-terminal 65-residue extension to the actin-like fold of Arp7A interacts directly with Tes. The crystal structure of the 1–65Arp7A·LIM2–3Tes·EVH1Mena complex reveals that residues 28–49 of Arp7A contact the LIM2–3 domains of Tes. Two alanine residues from Arp7A that occupy equivalent apolar pockets in both LIM domains as well as an intervening GPAK linker that binds the LIM2–3 junction are critical for the Arp7A-Tes interaction. Equivalent occupied apolar pockets are also seen in the tandem LIM domain structures of LMO4 and Lhx3 bound to unrelated ligands. Our results indicate that apolar pocket interactions are a common feature of tandem LIM domain interactions, but ligand specificity is principally determined by the linker sequence.