Popinako A, Antonov M, Dibrova D, Chemeris A, Sokolova O S
A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of RAS, 33 Leninsky Ave, bld. 2, Moscow, 119071, Russia.
M.K. Ammosov North-Eastern Federal University, 58 Belinskiy str, suite 312, Yakutsk, 677980, Republic of Sakha (Yakutia), Russia.
Biochem Biophys Res Commun. 2018 Feb 5;496(2):529-535. doi: 10.1016/j.bbrc.2018.01.080. Epub 2018 Jan 12.
The Arp2/3 complex plays a key role in nucleating actin filaments branching. The glia maturation factor (GMF) competes with activators for interacting with the Arp2/3 complex and initiates the debranching of actin filaments. In this study, we performed a comparative analysis of interactions between GMF and the Arp2/3 complex and identified new amino acid residues involved in GMF binding to the Arp2/3 complex at two separate sites, revealed by X-ray and single particle EM techniques. Using molecular dynamics simulations we demonstrated the quantitative and qualitative changes in hydrogen bonds upon binding with GMF. We identified the specific amino acid residues in GMF and Arp2/3 complex that stabilize the interactions and estimated the mean force profile for the GMF using umbrella sampling. Phylogenetic and structural analyses of the recently defined GMF binding site on the Arp3 subunit indicate a new mechanism for Arp2/3 complex inactivation that involves interactions between the Arp2/3 complex and GMF at two binding sites.
Arp2/3复合物在肌动蛋白丝分支成核过程中起关键作用。神经胶质成熟因子（GMF）与激活剂竞争与Arp2/3复合物相互作用，并启动肌动蛋白丝的去分支。在本研究中，我们对GMF与Arp2/3复合物之间的相互作用进行了比较分析，并通过X射线和单颗粒电子显微镜技术确定了GMF在两个不同位点与Arp2/3复合物结合所涉及的新氨基酸残基。使用分子动力学模拟，我们展示了与GMF结合时氢键的定量和定性变化。我们确定了GMF和Arp2/3复合物中稳定相互作用的特定氨基酸残基，并使用伞形采样估计了GMF的平均力分布。对Arp3亚基上最近定义的GMF结合位点的系统发育和结构分析表明，Arp2/3复合物失活的新机制涉及Arp2/3复合物与GMF在两个结合位点之间的相互作用。
