 |
PDBsum entry 3frr
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Protein binding
|
PDB id
|
|
|
|
3frr
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Structural basis for escrt-Iii protein autoinhibition.
|
|
|
Authors
|
|
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.
|
|
|
Ref.
|
|
Nat Struct Biol, 2009,
16,
754-762.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
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.
|
|
|
|
|
|
|
|
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.
|
|
|
|
|
|
|
