Use of Thallium to Identify Monovalent Cation Binding Sites in GroEL

Journal Article · Thu Jan 01 04:00:00 EST 2009 · Acta Crystallographica Section F: Structural Biology and Crystallization Communications

DOI:https://doi.org/10.1107/S1744309109032928· OSTI ID:980670

Kiser, P; Lorimer, G; Palczewski, K

GroEL is a bacterial chaperone protein that assembles into a homotetradecameric complex exhibiting D{sub 7} symmetry and utilizes the co-chaperone protein GroES and ATP hydrolysis to assist in the proper folding of a variety of cytosolic proteins. GroEL utilizes two metal cofactors, Mg{sup 2+} and K{sup +}, to bind and hydrolyze ATP. A K{sup +}-binding site has been proposed to be located next to the nucleotide-binding site, but the available structural data do not firmly support this conclusion. Moreover, more than one functionally significant K{sup +}-binding site may exist within GroEL. Because K{sup +} has important and complex effects on GroEL activity and is involved in both positive (intra-ring) and negative (inter-ring) cooperativity for ATP hydrolysis, it is important to determine the exact location of these cation-binding site(s) within GroEL. In this study, the K{sup +} mimetic Tl{sup +} was incorporated into GroEL crystals, a moderately redundant 3.94 {angstrom} resolution X-ray diffraction data set was collected from a single crystal and the strong anomalous scattering signal from the thallium ion was used to identify monovalent cation-binding sites. The results confirmed the previously proposed placement of K{sup +} next to the nucleotide-binding site and also identified additional binding sites that may be important for GroEL function and cooperativity. These findings also demonstrate the general usefulness of Tl{sup +} for the identification of monovalent cation-binding sites in protein crystal structures, even when the quality and resolution of the diffraction data are relatively low.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 980670
• Report Number(s): BNL--93588-2010-JA
• Journal Information: Acta Crystallographica Section F: Structural Biology and Crystallization Communications, Journal Name: Acta Crystallographica Section F: Structural Biology and Crystallization Communications Journal Issue: 10 Vol. 65
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ATP
CATIONS
CRYSTAL STRUCTURE
CRYSTALS
DATA
DIFFRACTION
FUNCTIONS
HYDROLYSIS
METALS
MONOCRYSTALS
PROTEINS
RESOLUTION
SCATTERING
SIGNALS
SUPPORTS
SYMMETRY
THALLIUM
THALLIUM IONS
USES
X-RAY DIFFRACTION
national synchrotron light source