Abstract
BackgroundLike all tripartite motif (TRIM) proteins, the retroviral restriction factor TRIM5α consists of RING, B-box 2 and coiled-coil domains, with a C-terminal B30.2(SPRY) domain. Although structures have been determined for some individual TRIM domains, the structure of an intact TRIM protein is unknown.ResultsHere, we express and characterize a protease-resistant 29-kD core fragment containing the B-box 2, coiled coil and adjacent linker (L2) region of TRIM5α. This BCCL2 protein formed dimers and higher-order oligomers in solution. Approximately 40% of the BCCL2 secondary structure consisted of alpha helices. Partial loss of alpha-helical content and dissociation of dimers occurred at 42°C, with the residual alpha helices remaining stable up to 80°C.ConclusionsThese results indicate that the B-box 2, coiled-coil and linker 2 regions of TRIM5α form a core dimerization motif that exhibits a high level of alpha-helical content.
Highlights
Like all tripartite motif (TRIM) proteins, the retroviral restriction factor TRIM5a consists of RING, B-box 2 and coiled-coil domains, with a C-terminal B30.2(SPRY) domain
The BCCL2 protein consists of an Nterminal His6 tag and a vector-derived spacer fused to the B-box 2 domain, the coiled-coil domain and the linker 2 (L2) region of TRIM5arh
The BCCL2 protein lacks a B30.2(SPRY) domain, which is needed for human immunodeficiency virus (HIV)-1 capsid binding and virus restriction [7,19,28,29], it retains the other TRIM5a domains required for
Summary
Like all tripartite motif (TRIM) proteins, the retroviral restriction factor TRIM5a consists of RING, B-box 2 and coiled-coil domains, with a C-terminal B30.2(SPRY) domain. Soon after entry into the cells of certain mammalian species, some retroviruses encounter blocks mediated by the restriction factor TRIM5a. Human immunodeficiency virus (HIV-1), the causative agent of acquired immunodeficiency syndrome (AIDS), can infect human and chimpanzee cells, but is blocked in cells of Old World monkeys [1,2,3,4,5]. TRIM5a, a member of the tripartite motif (TRIM) family of proteins, mediates these early infection blocks [7,8,9,10,11,12]. TRIM5a has been shown to bind and promote the premature uncoating of incoming retroviral capsids [13,14,15,16,17,18,19]
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