2K2X
Solution Structure of Tick Carboxypeptidase Inhibitor at pH 3.5
Summary for 2K2X
| Entry DOI | 10.2210/pdb2k2x/pdb |
| Related | 2K2Y 2K2Z |
| NMR Information | BMRB: 15729 |
| Descriptor | Carboxypeptidase inhibitor (1 entity in total) |
| Functional Keywords | tci, blood coagulation, fibrinolysis, metalloenzyme inhibitor, metalloprotease inhibitor, secreted, hydrolase inhibitor |
| Biological source | Rhipicephalus bursa (Tick) |
| Total number of polymer chains | 1 |
| Total formula weight | 7945.10 |
| Authors | Pantoja-Uceda, D.,Blanco, F. (deposition date: 2008-04-15, release date: 2009-01-27, Last modification date: 2024-11-20) |
| Primary citation | Arolas, J.L.,Pantoja-Uceda, D.,Ventura, S.,Blanco, F.J.,Aviles, F.X. The NMR structures of the major intermediates of the two-domain tick carboxypeptidase inhibitor reveal symmetry in its folding and unfolding pathways. J.Biol.Chem., 283:27110-27120, 2008 Cited by PubMed Abstract: There is a lack of experimental structural information about folding intermediates of multidomain proteins. Tick carboxypeptidase inhibitor (TCI) is a small, disulfide-rich protein consisting of two domains that fold and unfold autonomously through the formation of two major intermediates, IIIa and IIIb. Each intermediate contains three native disulfide bonds in one domain and six free cysteines in the other domain. Here we have determined the NMR structures of these two intermediates trapped and isolated at acidic pH in which they are stable and compared their structures with that of the native protein analyzed under the same conditions. Both IIIa and IIIb were found to contain a folded region that corresponds to the N- and C-terminal domains of TCI, respectively, with structures very similar to the corresponding regions of the native protein. The remainder of the polypeptide chains of the intermediates was shown to be unfolded in a random coil conformation. Solvent exchange measurements further indicated that the two protein domains are not completely independent, but affect each other in terms of dynamics and stability, in agreement with reported inhibitory activity data. The derived results provide structural evidence for symmetric TCI folding and unfolding mechanisms that converge in IIIa and IIIb and reveal the structural basis that accounts for the strong and simultaneous accumulation of both intermediates. Altogether, this work has important implications for a better understanding of the folding mechanisms of multidomain, disulfide-rich proteins. PubMed: 18640980DOI: 10.1074/jbc.M803978200 PDB entries with the same primary citation |
| Experimental method | SOLUTION NMR |
Structure validation
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