PDBsum entry: 1i6z

Chaperone

PDB id: 1i6z

Contents

Protein chain

135 a.a. *

* Residue conservation analysis

PDB id:

1i6z

Name:

Chaperone

Title:

Bag domain of bag1 cochaperone

Structure:

Bag-family molecular chaperone regulator-1. Chain: a. Fragment: bag domain. Synonym: bcl-2 binding athanogene-1, bag-1. Engineered: yes

Source:

Mus musculus. House mouse. Organism_taxid: 10090. Gene: bag1. Expressed in: escherichia coli. Expression_system_taxid: 562.

NMR struc:

25 models

Authors:

K.Briknarova,S.Takayama,L.Brive,M.L.Havert,D.A.Knee, J.Velasco,S.Homma,E.Cabezas,J.Stuart,D.W.Hoyt, A.C.Satterthwait,M.Llinas,J.C.Reed,K.R.Ely

Key ref:

K.Briknarová et al. (2001). Structural analysis of BAG1 cochaperone and its interactions with Hsc70 heat shock protein. Nat Struct Biol, 8, 349-352. PubMed id: 11276257 DOI: 10.1038/86236

Date:

06-Mar-01 Release date: 06-Sep-01

Protein chain

Q60739  (BAG1_MOUSE) -  BAG family molecular chaperone regulator 1

Seq: 355 a.a.

Struc: 135 a.a.*

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

 Gene Ontology (GO) functional annotation 

• Biochemical function: chaperone binding (1 term)

DOI no: 10.1038/86236

Nat Struct Biol 8:349-352 (2001)

PubMed id: 11276257

Structural analysis of BAG1 cochaperone and its interactions with Hsc70 heat shock protein.

K.Briknarová, S.Takayama, L.Brive, M.L.Havert, D.A.Knee, J.Velasco, S.Homma, E.Cabezas, J.Stuart, D.W.Hoyt, A.C.Satterthwait, M.Llinás, J.C.Reed, K.R.Ely.

ABSTRACT

BAG-family proteins share a conserved protein interaction region, called the 'BAG domain', which binds and regulates Hsp70/Hsc70 molecular chaperones. This family of cochaperones functionally regulates signal transducing proteins and transcription factors important for cell stress responses, apoptosis, proliferation, cell migration and hormone action. Aberrant overexpression of the founding member of this family, BAG1, occurs in human cancers. In this study, a structure-based approach was used to identify interacting residues in a BAG1--Hsc70 complex. An Hsc70-binding fragment of BAG1 was shown by multidimensional NMR methods to consist of an antiparallel three-helix bundle. NMR chemical shift experiments marked surface residues on the second (alpha 2) and third (alpha 3) helices in the BAG domain that are involved in chaperone binding. Structural predictions were confirmed by site-directed mutagenesis of these residues, resulting in loss of binding of BAG1 to Hsc70 in vitro and in cells. Molecular docking of BAG1 to Hsc70 and mutagenesis of Hsc70 marked the molecular surface of the ATPase domain necessary for interaction with BAG1. The results provide a structural basis for understanding the mechanism by which BAG proteins link molecular chaperones and cell signaling pathways.

Selected figure(s)

Figure 3.
Figure 3. Contact regions of the BAG1 -Hsc70 ATPase complex. The proteins are represented by red C traces and transparent surfaces of BAG1 on the left and Hsc70 ATPase domain15 on the right. An ADP molecule that binds in the cleft between the two lobes of the ATPase domain is shown in red as van der Waal's spheres. The complex has been 'opened up' by a 180° rotation of BAG1 to reveal the contact surfaces predicted from mutagenesis and molecular docking. The sites of mutation that abolish binding are colored yellow and adjacent contact sites suggested from molecular docking are colored cyan. This image was produced with the program SPOCK35.

Figure 4.
Figure 4. BAG domain is necessary for transactivation of AR by BAG1L. Mutant BAG1L proteins containing Ala substitutions within the BAG domain that ablated Hsc70 binding in vitro and a BAG1L truncation mutant lacking 3 of the BAG domain ( C) were tested. Mutant proteins are H2B (E157A, K161A in 2) and H3B (D197A, Q201A in 3). (These sites are numbered 283, 287, 323 and 327 in human BAG1L). Cos-7 cells were transfected with fixed amounts of pSG5-AR, pLCl, pCMV- Gal and increasing amounts of pcDNA3-BAG1L, wild type and mutants. Cell extracts were prepared and assayed for CAT and -galactosidase activity at 40 h after transfection. Data are expressed as fold transactivation relative to cells transfected with reporter gene alone (mean S.E.; n = 2).

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Struct Biol (2001, 8, 349-352) copyright 2001.

Figures were selected by an automated process.