Structural Dynamics Control Allosteric Activation of Cytohesin Family Arf GTPase Exchange Factors.

• 影响指数: 5.871
• 发表时间: 01 2018 2
• 来源期刊: Structure
• DOI: 10.1016/j.str.2017.11.019
• PMID: 29276036
• 文章类型: Journal Article
• 中科院分区: Q1
• 方向: 生物
• 作者列表: Malaby AW,Das S,Chakravarthy S,Irving TC,Bilsel O,Lambright DG

关键词: Arf; GTPase; Grp1; PH domain; Sec7 domain; autoinhibition; cytohesin; electron microscopy; guanine nucleotide exchange factor; small-angle X-ray scattering

Mesh: ADP-Ribosylation Factor 6; ADP-Ribosylation Factors / chemistry genetics metabolism; Allosteric Regulation; Allosteric Site; Amino Acid Sequence; Animals; Cloning, Molecular; Escherichia coli / genetics metabolism; Gene Expression; Genetic Vectors / chemistry metabolism; Guanine Nucleotide Exchange Factors / chemistry genetics metabolism; Guanosine Triphosphate / chemistry metabolism; Humans; Kinetics; Mice; Molecular Dynamics Simulation; Pleckstrin Homology Domains; Protein Binding; Protein Conformation, alpha-Helical; Protein Conformation, beta-Strand; Receptors, Cytoplasmic and Nuclear / chemistry genetics metabolism; Recombinant Fusion Proteins / chemistry genetics metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Substrate Specificity

Abstract

Membrane dynamic processes including vesicle biogenesis depend on Arf guanosine triphosphatase (GTPase) activation by guanine nucleotide exchange factors (GEFs) containing a catalytic Sec7 domain and a membrane-targeting module such as a pleckstrin homology (PH) domain. The catalytic output of cytohesin family Arf GEFs is controlled by autoinhibitory interactions that impede accessibility of the exchange site in the Sec7 domain. These restraints can be relieved through activator Arf-GTP binding to an allosteric site comprising the PH domain and proximal autoinhibitory elements (Sec7-PH linker and C-terminal helix). Small-angle X-ray scattering and negative-stain electron microscopy were used to investigate the structural organization and conformational dynamics of cytohesin-3 (Grp1) in autoinhibited and active states. The results support a model in which hinge dynamics in the autoinhibited state expose the activator site for Arf-GTP binding, while subsequent C-terminal helix unlatching and repositioning unleash conformational entropy in the Sec7-PH linker to drive exposure of the exchange site.