1K91

Solution Structure of Calreticulin P-domain subdomain (residues 221-256)

Summary for 1K91

• Entry DOI: 10.2210/pdb1k91/pdb
• Related: 1HHN 1K9C
• NMR Information: BMRB: 5205
• Descriptor: CALRETICULIN (1 entity in total)
• Functional Keywords: hairpin, metal transport
• Biological source: Rattus norvegicus (Norway rat)
• Cellular location: Endoplasmic reticulum lumen: P18418
• Total number of polymer chains: 1
• Total formula weight: 4308.62

Authors

Ellgaard, L.,Bettendorff, P.,Braun, D.,Herrmann, T.,Fiorito, F.,Guntert, P.,Helenius, A.,Wuthrich, K. (deposition date: 2001-10-26, release date: 2002-10-12, Last modification date: 2024-05-22)

Primary citation

Ellgaard, L.,Bettendorff, P.,Braun, D.,Herrmann, T.,Fiorito, F.,Jelesarov, I.,Guntert, P.,Helenius, A.,Wuthrich, K.
NMR Structures of 36 and 73-residue Fragments of the Calreticulin P-domain
J.Mol.Biol., 322:773-784, 2002

PubMed Abstract: Calreticulin (CRT) is an abundant, soluble molecular chaperone of the endoplasmic reticulum. Similar to its membrane-bound homolog calnexin (CNX), it is a lectin that promotes the folding of proteins carrying N-linked glycans. Both proteins cooperate with an associated co-chaperone, the thiol-disulfide oxidoreductase ERp57. This enzyme catalyzes the formation of disulfide bonds in CNX and CRT-bound glycoprotein substrates. Previously, we solved the NMR structure of the central proline-rich P-domain of CRT comprising residues 189-288. This structure shows an extended hairpin topology, with three short anti-parallel beta-sheets, three small hydrophobic clusters, and one helical turn at the tip of the hairpin. We further demonstrated that the residues 225-251 at the tip of the CRT P-domain are involved in direct contacts with ERp57. Here, we show that the CRT P-domain fragment CRT(221-256) constitutes an autonomous folding unit, and has a structure highly similar to that of the corresponding region in CRT(189-288). Of the 36 residues present in CRT(221-256), 32 form a well-structured core, making this fragment one of the smallest known natural sequences to form a stable non-helical fold in the absence of disulfide bonds or tightly bound metal ions. CRT(221-256) comprises all the residues of the intact P-domain that were shown to interact with ERp57. Isothermal titration microcalorimetry (ITC) now showed affinity of this fragment for ERp57 similar to that of the intact P-domain, demonstrating that CRT(221-256) may be used as a low molecular mass mimic of CRT for further investigations of the interaction with ERp57. We also solved the NMR structure of the 73-residue fragment CRT(189-261), in which the tip of the hairpin and the first beta-sheet are well structured, but the residues 189-213 are disordered, presumably due to lack of stabilizing interactions across the hairpin.

PubMed: 12270713
DOI: 10.1016/S0022-2836(02)00812-4

Experimental method

SOLUTION NMR