1HPM

HOW POTASSIUM AFFECTS THE ACTIVITY OF THE MOLECULAR CHAPERONE HSC70. II. POTASSIUM BINDS SPECIFICALLY IN THE ATPASE ACTIVE SITE

• PDB DOI: https://doi.org/10.2210/pdb1HPM/pdb

• Classification: HYDROLASE (ACTING ON ACID ANHYDRIDES)
• Organism(s): Bos taurus
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 1995-03-24 Released: 1995-07-31 
• Deposition Author(s): Wilbanks, S.M., Mckay, D.B.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.70 Å
• R-Value Work: 0.205 
• R-Value Observed: 0.205 

Literature

How potassium affects the activity of the molecular chaperone Hsc70. II. Potassium binds specifically in the ATPase active site.

Wilbanks, S.M., McKay, D.B.

(1995) J Biol Chem 270: 2251-2257

• PubMed: 7836458 
• DOI: https://doi.org/10.1074/jbc.270.5.2251
• Primary Citation of Related Structures:  
  1HPM


• PubMed Abstract: 
  

  Crystallographic anomalous scattering from potassium at 1.7 A resolution reveals two monovalent ions that interact with MgADP and P(i) in the nucleotide binding cleft of wild-type recombinant bovine Hsc70 ATPase fragment. K+ at site 1 interacts with oxygens of the beta-phosphate of ADP, whereas K+ at site 2 interacts with an oxygen of P(i). Both K+ ions also interact with specific H2O molecules in the first hydration shell of the octahedrally coordinated Mg2+ ion and with specific protein ligands. In crystals that have Na+ present, K+ is replaced by a Na+ ion at site 1 and by a Na(+)-H2O pair at site 2. The K+ ions are positioned where they could stabilize binding of a beta,gamma-bidentate MgATP complex with Hsc70, as well as a transition state during ATP hydrolysis, suggesting that monovalent ions act as specific metal cofactors in the ATPase reaction of Hsc70.

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Organizational Affiliation: 

Beckman Laboratories for Structural Biology, Stanford University School of Medicine, California 94305.

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 43.21 kDa 
• Atom Count: 3,360 
• Modelled Residue Count: 378 
• Deposited Residue Count: 386 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
44K ATPASE FRAGMENT (N-TERMINAL) OF 7O kD HEAT-SHOCK COGNATE PROTEIN	A	386	Bos taurus	Mutation(s): 0  EC: 3.6.1.3 (PDB Primary Data), 3.6.4.10 (UniProt)
UniProt
Find proteins for P19120 (Bos taurus) Explore P19120  Go to UniProtKB:  P19120

Small Molecules

Ligands 5 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
ADP	H [auth A]	ADENOSINE-5'-DIPHOSPHATE C10 H15 N5 O10 P2 XTWYTFMLZFPYCI-KQYNXXCUSA-N
PO4	C [auth A]	PHOSPHATE ION O4 P NBIIXXVUZAFLBC-UHFFFAOYSA-K
K	D [auth A], E [auth A]	POTASSIUM ION K NPYPAHLBTDXSSS-UHFFFAOYSA-N
CL	F [auth A], G [auth A]	CHLORIDE ION Cl VEXZGXHMUGYJMC-UHFFFAOYSA-M
MG	B [auth A]	MAGNESIUM ION Mg JLVVSXFLKOJNIY-UHFFFAOYSA-N

Binding Affinity Annotations
ID	Source	Binding Affinity
ADP	BindingDB:  1HPM	Kd: min: 320, max: 324 (nM) from 2 assay(s)
		IC50: 280 (nM) from 1 assay(s)

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.70 Å
• R-Value Work: 0.205 
• R-Value Observed: 0.205 
• Space Group: P 2₁ 2₁ 2₁

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 143.9	α = 90
b = 63.7	β = 90
c = 46.2	γ = 90

Software Package:

Software Name	Purpose
X-PLOR	model building
X-PLOR	refinement
X-PLOR	phasing

Structure Validation

Entry History 

Deposition Data

• Released Date: 1995-07-31 
Deposition Author(s): Wilbanks, S.M., Mckay, D.B.

Revision History  

• Version 1.0: 1995-07-31
  Type: Initial release
  
• Version 1.1: 2008-03-24
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2024-02-07
  Changes: Data collection, Database references, Derived calculations, Other