PDBsum entry 3frs

Protein binding

PDB id: 3frs

Contents

Protein chain

175 a.a. *

Ligands

GOL

Waters ×35

* Residue conservation analysis

PDB id:

3frs

Name:

Protein binding

Title:

Structure of human ist1(ntd) (residues 1-189)(p43212)

Structure:

Uncharacterized protein kiaa0174. Chain: a. Fragment: unp residues 1-189. Synonym: putative mapk-activating protein pm28. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: ist1, kiaa0174. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.61Å R-factor: 0.261 R-free: 0.298

Authors:

H.L.Schubert,C.P.Hill,M.Bajorek,W.I.Sundquist

Key ref:

M.Bajorek et al. (2009). Structural basis for ESCRT-III protein autoinhibition. Nat Struct Biol, 16, 754-762. PubMed id: 19525971 DOI: 10.1038/nsmb.1621

Date:

08-Jan-09 Release date: 30-Jun-09

Protein chain

P53990  (IST1_HUMAN) -  IST1 homolog from Homo sapiens

Seq: 364 a.a.

Struc: 175 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1038/nsmb.1621

Nat Struct Biol 16:754-762 (2009)

PubMed id: 19525971

Structural basis for ESCRT-III protein autoinhibition.

M.Bajorek, H.L.Schubert, J.McCullough, C.Langelier, D.M.Eckert, W.M.Stubblefield, N.T.Uter, D.G.Myszka, C.P.Hill, W.I.Sundquist.

ABSTRACT

Endosomal sorting complexes required for transport-III (ESCRT-III) subunits cycle between two states: soluble monomers and higher-order assemblies that bind and remodel membranes during endosomal vesicle formation, midbody abscission and enveloped virus budding. Here we show that the N-terminal core domains of increased sodium tolerance-1 (IST1) and charged multivesicular body protein-3 (CHMP3) form equivalent four-helix bundles, revealing that IST1 is a previously unrecognized ESCRT-III family member. IST1 and its ESCRT-III binding partner, CHMP1B, both form higher-order helical structures in vitro, and IST1-CHMP1 interactions are required for abscission. The IST1 and CHMP3 structures also reveal that equivalent downstream alpha5 helices can fold back against the core domains. Mutations within the CHMP3 core-alpha5 interface stimulate the protein's in vitro assembly and HIV-inhibition activities, indicating that dissociation of the autoinhibitory alpha5 helix from the core activates ESCRT-III proteins for assembly at membranes.

Selected figure(s)

Figure 1.
(a–c) Equilibrium sedimentation distributions of recombinant CHMP3 (a), CHMP3[8–222] (b) and IST1[NTD] (c) (above), and residual differences (below), with data points shown in open symbols and the single species models shown as solid lines. Rotor speeds were 20,000 r.p.m. and the initial subunit protein concentrations are shown. Data sets were also collected at 24,000 r.p.m. (not shown) and all of the data were globally fit to single species models in which the molecular weights were allowed to float during the refinement. Estimated molecular weights were: CHMP3, 25,840 Da (molecular weight of the monomer (MW[monomer]) = 25,267 Da, M[obs]/M[calc] = 1.02); CHMP3[8–222], 24,390 Da (MW[monomer] = 24,663 Da, M[obs]/M[calc] = 0.99); IST1[NTD], 20,520 Da (MW[monomer] = 21,791 Da, M[obs]/M[calc] = 0.94).

Figure 2.
(a) Ribbon diagram and helix-labeling scheme for IST1[NTD]. (b) Overlay of the ordered regions of IST1[NTD] and CHMP3[8–183]. (c) Ribbon diagram of CHMP3[8–222]. (d) Space-filling model of IST1[NTD], color coded to show the surface charge distribution (blue, basic; red, acidic; 7 kV)^35 (created using PyMOL (http://pymol.sourceforge.net)). The molecule is shown in the same orientation as in a. (e) Same as d with the view toward 1. Figure generated from d by rotation about the horizontal so that the bottom edge of d faces the viewer. (f) Space-filling model of CHMP3[8–222] shown in an equivalent orientation to the view of IST1[NTD] shown in e, emphasizing the basicity of the 1 surface of CHMP3 (ref.

The above figures are reprinted from an Open Access publication published by Macmillan Publishers Ltd: Nat Struct Biol (2009, 16, 754-762) copyright 2009.

Figures were selected by an automated process.