TRIM5α association with cytoplasmic bodies is not required for antiretroviral activity

The tripartite motif (TRIM) protein, TRIN15 alpha, restricts infection by particular retroviruses. Many TRIM proteins form cytoplasmic bodies of unknown function. We investigated the relationship between cytoplasmic body formation and the structure and antiretroviral activity of TRIM5 alpha. In addition to diffuse cytoplasmic staining, the TRIM5 alpha proteins from several primate species were located in cytoplasmic bodies of different sizes; by contrast, TRIM5 alpha from spider monkeys did not form cytoplasmic bodies. Despite these differences, all of the TRIM5 alpha proteins exhibited the ability to restrict infection by particular retroviruses. Treatment of cells with geldanamycin, an Hsp90 inhibitor, resulted in disappearance or reduction of the TRIM5 alpha-associated cytoplasmic bodies, yet exerted little effect on the restriction of retroviral infection. Studies of green fluorescent protein-TRIM5 alpha fusion proteins indicated that no TRIM5a domain is specifically required for association with cytoplasmic bodies. Apparently, the formation of cytoplasmic bodies is not required for the antiretroviral activity of TRIM5 alpha. (c) 2005 Elsevier Inc. All rights reserved.