Dataset Information

A3G-Vif-CBFB-CRL5 Cross-Linking with DSSO

ABSTRACT: Here we use an optimization cross-linking mass spectrometry (XL-MS) pipeline for the structural characterization of a dynamic HIV-host protein complex. Using DSSO-based XL-MS analysis, residue-protein proximity restraints based on functional genetics, and integrative modeling, we define the structure of the HIV-1 Vif protein bound to restriction factor APOBEC3G (A3G), the Cullin-5 E3 ring ligase (CRL5), and the cellular transcription factor Core Binding Factor Beta (CBFβ). Using a XL-MS3 methodology, we identify 132 inter-linked peptides and integrate the data with atomic structures of the subunits and mutagenesis data, and computed an integrative structure model of the heptameric A3G-CRL5-Vif-CBFβ complex. The resulting model ensemble quantifies the dynamic heterogenity of the A3G C-terminal domain, as well as CUL5 flexibility, and defines the interface between Vif and A3G. Our model can be used to rationalize previous structural, mutatagenesis, and functional data not included in modeling. The experimental and computational approach described here is generally applicable to other challenging host-pathogen protein complexes and provides new visualization tools for characterizing cross-linking data.

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Homo Sapiens (human) Human Immunodeficiency Virus

SUBMITTER: Robyn Kaake

LAB HEAD: Nevan J. Krogan

PROVIDER: PXD025391 | Pride | 2021-11-03

REPOSITORIES: Pride

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Publications

Characterization of an A3G-Vif<sub>HIV-1</sub>-CRL5-CBFβ Structure Using a Cross-linking Mass Spectrometry Pipeline for Integrative Modeling of Host-Pathogen Complexes.

Kaake Robyn M RM Echeverria Ignacia I Kim Seung Joong SJ Von Dollen John J Chesarino Nicholas M NM Feng Yuqing Y Yu Clinton C Ta Hai H Chelico Linda L Huang Lan L Gross John J Sali Andrej A Krogan Nevan J NJ

Molecular & cellular proteomics : MCP 20210811

Structural analysis of host-pathogen protein complexes remains challenging, largely due to their structural heterogeneity. Here, we describe a pipeline for the structural characterization of these complexes using integrative structure modeling based on chemical cross-links and residue-protein contacts inferred from mutagenesis studies. We used this approach on the HIV-1 Vif protein bound to restriction factor APOBEC3G (A3G), the Cullin-5 E3 ring ligase (CRL5), and the cellular transcription fact ...[more]

PMID: 34389466

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Project description:Mycobacterium polyketide synthase 13 (Pks13) is a protein complex comprised of a closely symmetric parallel dimer of chains, each encoding several enzymatic and transport functions. This module carries out the condensation of two different very long chain fatty acids to produce mycolic acids that are essential components of the mycobacterial cell wall. Here, we use cryo-EM, XL-MS, and integrative modeling to determine the structure and domain trajectories of the dimeric multi-enzyme Pks13 purified endogenously from mycobacteria under normal growth conditions. Structures of the multi-domain assembly revealed by cryogenic electron microscopy (cryoEM) define the ketosynthase (KS), linker, and acyltransferase (AT) domains, each at atomic resolution (1.8Å), with bound substrates defined at 2.4Å and 2.9Å resolution. Image classification reveals two distinct structures with alternate locations of the N-terminal acyl carrier protein (termed ACP1a, ACP1b) seen at 3.6Å and 4.6Å resolution respectively. These two structures suggest plausible intermediate states, related by a ~60Å movement of ACP1, on the pathway for substrate delivery from the fatty acyl-ACP ligase (FadD32) to the ketosynthase domain. The linking sequence between ACP1 and the KS includes an 11 amino acid sequence with 6 negatively charged side chains that lies in different positively charged grooves on the KS in ACP1a versus ACP1b structures. This charge complementarity between the extended chain and the grooves suggests some stabilization of these two distinct orientations. Other domains are visible at lower resolution and indicate flexibility relative to the KS-AT core. The chemical structures of three bound endogenous long chain fatty acid substrates with their proximal regions defined in the structures were determined by electrospray ionization mass spectrometry. The domain proximities were probed by chemical cross-linking and identified by mass spectrometry (XL-MS). These were incorporated into integrative structure modeling to define multiple domain configurations that transport the very long fatty acid chains throughout the multistep Pks13 mediated synthetic pathway.

Dataset Information

A3G-Vif-CBFB-CRL5 Cross-Linking with DSSO

Publications

Characterization of an A3G-Vif<sub>HIV-1</sub>-CRL5-CBFβ Structure Using a Cross-linking Mass Spectrometry Pipeline for Integrative Modeling of Host-Pathogen Complexes.

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