PDBsum entry: 2byu

Chaperone

PDB id: 2byu

Contents

Protein chains

(+ 6 more) 101 a.a. *

* Residue conservation analysis

PDB id:

2byu

Name:

Chaperone

Title:

Negative stain em reconstruction of m.Tuberculosis acr1(hsp 16.3) fitted with wheat shsp dimer

Structure:

Heat shock protein 16.9b. Chain: a, b, c, d, e, f, g, h, i, j, k, l. Other_details: this entry contains the coordinates of wheat hsp 16.9 which have been fitted into the cryo-em reconstruction of hsp 16.3 from m.Tuberculosis. The compnd and source records give details of the protein represented by the coordinates, rather than the protein from which the em map was derived

Source:

Triticum aestivum. Wheat. Organism_taxid: 4565. Other_details: the protein model was obtained from PDB entry 1gme

Biol. unit:

Dodecamer (from PDB file)

Authors:

C.K.Kennaway,J.L.P.Benesch,U.Gohlke,L.Wang,C.V.Robinson, E.V.Orlova,H.R.Saibil,N.H.Keep

Key ref:

C.K.Kennaway et al. (2005). Dodecameric structure of the small heat shock protein Acr1 from Mycobacterium tuberculosis. J Biol Chem, 280, 33419-33425. PubMed id: 16046399 DOI: 10.1074/jbc.M504263200

Date:

05-Aug-05 Release date: 22-Aug-05

Protein chains

Q41560  (HS16B_WHEAT) -  16.9 kDa class I heat shock protein 2

Seq: 151 a.a.

Struc: 101 a.a.

DOI no: 10.1074/jbc.M504263200

J Biol Chem 280:33419-33425 (2005)

PubMed id: 16046399

Dodecameric structure of the small heat shock protein Acr1 from Mycobacterium tuberculosis.

C.K.Kennaway, J.L.Benesch, U.Gohlke, L.Wang, C.V.Robinson, E.V.Orlova, H.R.Saibil, H.R.Saibi, N.H.Keep.

ABSTRACT

Small heat shock proteins are a ubiquitous and diverse family of stress proteins that have in common an alpha-crystallin domain. Mycobacterium tuberculosis has two small heat shock proteins, Acr1 (alpha-crystallin-related protein 1, or Hsp16.3/16-kDa antigen) and Acr2 (HrpA), both of which are highly expressed under different stress conditions. Small heat shock proteins form large oligomeric assemblies and are commonly polydisperse. Nanoelectrospray mass spectrometry showed that Acr2 formed a range of oligomers composed of dimers and tetramers, whereas Acr1 was a dodecamer. Electron microscopy of Acr2 showed a variety of particle sizes. Using three-dimensional analysis of negative stain electron microscope images, we have shown that Acr1 forms a tetrahedral assembly with 12 polypeptide chains. The atomic structure of a related alpha-crystallin domain dimer was docked into the density to build a molecular structure of the dodecameric Acr1 complex. Along with the differential regulation of these two proteins, the differences in their quaternary structures demonstrated here supports their distinct functional roles.

Selected figure(s)

Figure 2.
FIGURE 2. A, Acr2 (+His) nanoelectrospray mass spectrometry spectrum showing a range of different sized complexes. Analysis of the individual peaks by argon collision-induced dissociation reveals homo-oligomers consisting of even numbers of subunits from 12 up to 28, as well as other larger assemblies. B, nanoelectrospray mass spectrometry of Acr1 reveals the protein to exist as a dodecamer. The individual charge states of the peaks are labeled.

Figure 6.
FIGURE 6. A, surface representation of the three-dimensional map of Acr1 contoured at 2.2 , viewed down a 2-fold axis. The black line beneath is a 100 Å scale bar. B, model of Acr1 using the wheat -crystallin dimers. N-terminal residues 1-42 are omitted because of their unknown structure and likely flexibility. C-terminal residues 146-151 containing the IXI motif are shown in magenta, positioned as they are in the wheat crystal structure. These 6 residues occupy bulges in the density along the outer edges, seen most clearly at the top and bottom of this view. C, contacts between dimers are formed by the C-terminal extensions. Residues 146-151 (magenta sticks) can be seen binding to the edges of -sheets 3 and 7 of an -crystallin domain in an adjacent dimer (blue). The surface of the Acr1 EM reconstruction is shown, and the truncated end (residue 137) of the green -crystallin domain is shown colored red. The general direction of the path of the omitted residues is shown as a yellow dashed line. Figures were produced with Pymol (www.pymol.org).

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2005, 280, 33419-33425) copyright 2005.

Figures were selected by the author.