1qx2
|
X-ray Structure of Calcium-loaded Calbindomodulin (A Calbindin D9k Re-engineered to Undergo a Conformational Opening) at 1.44 A Resolution
OverviewOverview
The extent of conformational change that calcium binding induces in, EF-hand proteins is a key biochemical property specifying Ca(2+) sensor, versus signal modulator function. To understand how differences in amino, acid sequence lead to differences in the response to Ca(2+) binding, comparative analyses of sequence and structures, combined with model, building, were used to develop hypotheses about which amino acid residues, control Ca(2+)-induced conformational changes. These results were used to, generate a first design of calbindomodulin (CBM-1), a calbindin D(9k), re-engineered with 15 mutations to respond to Ca(2+) binding with a, conformational change similar to that of calmodulin. The gene for CBM-1, was synthesized, and the protein was expressed and purified. Remarkably, this protein did not exhibit any non-native-like molten globule properties, despite the large number of mutations and the nonconservative nature of, some of them. Ca(2+)-induced changes in CD intensity and in the binding of, the hydrophobic probe, ANS, implied that CBM-1 does undergo Ca(2+), sensorlike conformational changes. The X-ray crystal structure of, Ca(2+)-CBM-1 determined at 1.44 A resolution reveals the anticipated, increase in hydrophobic surface area relative to the wild-type protein. A, nascent calmodulin-like hydrophobic docking surface was also found, though, it is occluded by the inter-EF-hand loop. The results from this first, calbindomodulin design are discussed in terms of progress toward, understanding the relationships between amino acid sequence, protein, structure, and protein function for EF-hand CaBPs, as well as the, additional mutations for the next CBM design.
About this StructureAbout this Structure
1QX2 is a Single protein structure of sequence from Bos taurus with CA and ZN as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Designing sequence to control protein function in an EF-hand protein., Bunick CG, Nelson MR, Mangahas S, Hunter MJ, Sheehan JH, Mizoue LS, Bunick GJ, Chazin WJ, J Am Chem Soc. 2004 May 19;126(19):5990-8. PMID:15137763
Page seeded by OCA on Wed Nov 21 01:05:01 2007