Unique features of TRIM5α among closely related human TRIM family members

The tripartite motif (TRIM) protein, TRIM5 alpha, restricts some retroviruses, including human immunodeficiency virus (HIV-1), from infecting the cells of particular species. TRIM proteins contain RING, B-box, coiled-coil and, in some cases, B30.2(SPRY) domains. We investigated the properties of human TRIM family members closely related to TRIM5. These TRIM proteins, like TRIM5 alpha, assembled into homotrimers and colocalized in the cytoplasm with TRIM5 alpha. TRIM5 alpha turned over more rapidly than related TRIM proteins. TRIM5 alpha, TRIM34 and TRIM6 associated with HIV-1 capsid-nucleocapsid complexes assembled in vitro; the TRIM5 alpha and TRIM34 interactions with these complexes were dependent on their B30.2(SPRY) domains. Only TRIM5 alpha potently restricted infection by the retroviruses studied; overexpression of TRIM34 resulted in modest inhibition of simian immunodeficiency virus (SIVmac) infection. In contrast to the other TRIM genes examined, TRIM5 exhibited evidence of positive selection. The unique features of TRIM5 alpha among its TRIM relatives underscore its special status as an antiviral factor. (c) 2006 Elsevier Inc. All rights reserved.