Structural Organization and Dynamics of Homodimeric Cytohesin Family Arf GTPase Exchange Factors in Solution and on Membranes

Journal Article · Sun Dec 01 00:00:00 EST 2019 · Structure

DOI:https://doi.org/10.1016/j.str.2019.09.007· OSTI ID:1580152

Das, Sanchaita; Malaby, Andrew W.; Nawrotek, Agata; Zhang, Wenhua; Zeghouf, Mahel; Maslen, Sarah; Skehel, Mark; Chakravarthy, Srinivas; Irving, Thomas C.; Bilsel, Osman; Cherfils, Jacqueline; Lambright, David G.

Membrane dynamic processes require Arf GTPase activation by guanine nucleotide exchange factors (GEFs) with a Sec7 domain. Cytohesin family Arf GEFs function in signaling and cell migration through Arf GTPase activation on the plasma membrane and endosomes. In this study, the structural organization of two cytohesins (Grp1 and ARNO) was investigated in solution by size exclusion-small angle X-ray scattering and negative stain-electron microscopy and on membranes by dynamic light scattering, hydrogen-deuterium exchange-mass spectrometry and guanosine diphosphate (GDP)/guanosine triphosphate (GTP) exchange assays. The results suggest that cytohesins form elongated dimers with a central coiled coil and membrane-binding pleckstrin-homology (PH) domains at opposite ends. Here, the dimers display significant conformational heterogeneity, with a preference for compact to intermediate conformations. Phosphoinositide-dependent membrane recruitment is mediated by one PH domain at a time and alters the conformational dynamics to prime allosteric activation by Arf-GTP. A structural model for membrane targeting and allosteric activation of full-length cytohesin dimers is discussed.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division; National Institute Health (NIH)
• Grant/Contract Number: AC02-06CH11357; GM056324
• OSTI ID: 1580152
• Alternate ID(s): OSTI ID: 1576873; OSTI ID: 1578202
• Journal Information: Structure, Journal Name: Structure Vol. 27 Journal Issue: 12; ISSN 0969-2126
• Publisher: Elsevier
• Country of Publication: United Kingdom
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
GEF
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EM
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MS
autoinhibition
structure