Functional Replacement of the RING, B-Box 2, and Coiled-Coil Domains of Tripartite Motif 5α (TRIM5α) by Heterologous TRIM Domains

Abstract

ABSTRACT Tripartite motif 5α (TRIM5α) restricts some retroviruses, including human immunodeficiency virus type 1 (HIV-1), from infecting the cells of particular species. TRIM5α is a member of the TRIM family of proteins, which contain RING, B-box, coiled-coil (CC), and, in some cases, B30.2(SPRY) domains. Here we investigated the abilities of domains from TRIM proteins (TRIM6, TRIM34, and TRIM21) that do not restrict HIV-1 infection to substitute for the domains of rhesus monkey TRIM5α (TRIM5α rh ). The RING, B-box 2, and CC domains of the paralogous TRIM6 and TRIM34 proteins functionally replaced the corresponding TRIM5α rh domains, allowing HIV-1 restriction. By contrast, similar chimeras containing the components of TRIM21, a slightly more distant relative of TRIM5, did not restrict HIV-1 infection. The TRIM21 B-box 2 domain and its flanking linker regions contributed to the functional defectiveness of these chimeras. All of the chimeric proteins formed trimers. All of the chimeras that restricted HIV-1 infection bound the assembled HIV-1 capsid complexes. These results indicate that heterologous RING, B-box 2, and CC domains from related TRIM proteins can functionally substitute for TRIM5α rh domains.