1g03
From Proteopedia
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NMR STRUCTURE OF N-TERMINAL DOMAIN OF HTLV-I CA1-134
Overview
The N-terminal domain of the retroviral capsid (CA) protein is one of the, least conserved regions encoded in the genome. Surprisingly, the, three-dimensional structures of the CA from different genera exhibit, alpha-helical structural features that are highly conserved. The, N-terminal residues of the human immunodeficiency virus type 1 (HIV-1) and, Rous sarcoma virus (RSV) capsid proteins form a beta-hairpin. To determine, if this feature is conserved in the retroviral family, we cloned, expressed, purified, and solved the structure of a N-terminal 134 amino, acid fragment (CA(134)) from the human T-cell leukemia virus type 1, (HTLV-I) using high resolution nuclear magnetic resonance (NMR), spectroscopy. The CA(134) fragment contains an N-terminal beta-hairpin and, a central coiled-coil-like structure composed of six alpha-helices. The, N-terminal Pro1 residue contacts Asp54 in the helical cluster through a, salt bridge. Thus, the beta-hairpin is conserved and the helical cluster, is structurally similar to other retroviral CA domains. However, although, the same Asp residue defines the orientation of the hairpin in both the, HTLV-1 and HIV-1 CA proteins, the HTLV-I hairpin is oriented away, rather, than towards, the helical core. Significant differences were also detected, in the spatial orientation and helical content of the long centrally, located loop connecting the helices in the core. It has been proposed that, the salt bridge allows the formation of a CA-CA interface that is, important for the assembly of the conical cores that are characteristic of, HIV-1. As HTLV-I forms spherical cores, the salt-bridge feature is, apparently not conserved for this function although its role in, determining the orientation of the beta-hairpin may be critical, along, with the central loop. Comparison of three-dimensional structures is, expected to elucidate the relationships between the retroviral capsid, protein structure and its function.
About this Structure
1G03 is a Single protein structure of sequence from Human t-lymphotropic virus 1. Full crystallographic information is available from OCA.
Reference
Structural analysis of the N-terminal domain of the human T-cell leukemia virus capsid protein., Cornilescu CC, Bouamr F, Yao X, Carter C, Tjandra N, J Mol Biol. 2001 Mar 2;306(4):783-97. PMID:11243788
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