Evolution of a TRIM5-CypA splice isoform in old world monkeys

• Published in: PLoS pathogens Vol. 4; no. 2; p. e1000003
• Main Authors: Newman, Ruchi M, Hall, Laura, Kirmaier, Andrea, Pozzi, Lu-Ann, Pery, Erez, Farzan, Michael, O'Neil, Shawn P, Johnson, Welkin
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.02.2008; Public Library of Science (PLoS)
• Subjects: Amino Acid Sequence; Animals; Aotus; B-Lymphocytes - immunology; B-Lymphocytes - metabolism; Cercopithecidae; Cyclophilin A - genetics; Cyclophilin A - metabolism; DNA binding proteins; Evolution, Molecular; Evolutionary Biology/Evolutionary and Comparative Genetics; Experiments; Genetic aspects; Genetic transcription; Genotype; HIV infection; HIV Infections - genetics; HIV Infections - immunology; HIV Infections - metabolism; HIV-1; Homozygote; Human immunodeficiency virus 1; Immunity, Innate; Infections; Lentivirus; Leukocytes, Mononuclear - drug effects; Leukocytes, Mononuclear - immunology; Leukocytes, Mononuclear - metabolism; Lymphocytes; Macaca mulatta; Molecular Sequence Data; Monkey Diseases - genetics; Monkey Diseases - immunology; Monkey Diseases - metabolism; Mutant Chimeric Proteins - genetics; Mutation; Physiological aspects; Phytohemagglutinins - pharmacology; Plasmids; Polymorphism, Single Nucleotide; Primates; Protein Isoforms - genetics; Protein Isoforms - metabolism; Protein Structure, Tertiary; Proteins; Proteins - genetics; Proteins - metabolism; Retrovirus; Risk factors; Simian immunodeficiency virus; Virology; Virology/Animal Models of Infection; Virology/Immunodeficiency Viruses; Virology/Mechanisms of Resistance and Susceptibility, including Host Genetics; United States
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1000003

The TRIM family proteins share a conserved arrangement of three adjacent domains, an N-terminal RING domain, followed by one or two B-boxes and a coiled-coil, which constitutes the tripartite-motif for which the family is named. However, the C-termini of TRIM proteins vary, and include at least nine evolutionarily distinct, unrelated protein domains. Antiviral restriction factor TRIM5alpha has a C-terminal B30.2/SPRY domain, which is the major determinant of viral target specificity. Here, we describe the evolution of a cyclophilin-A encoding exon downstream of the TRIM5 locus of Asian macaques. Alternative splicing gives rise to chimeric transcripts encoding the TRIM motif fused to a C-terminal CypA domain (TRIM5-CypA). We detected TRIM5-CypA chimeric transcripts in primary lymphocytes from two macaque species. These were derived in part from a CypA pseudogene in the TRIM5 locus, which is distinct from the previously described CypA insertion in TRIM5 of owl monkeys. The CypA insertion is linked to a mutation in the 3' splice site upstream of exon 7, which may prevent or reduce expression of the alpha-isoform. All pig-tailed macaques (M. nemestrina) screened were homozygous for the CypA insertion. In contrast, the CypA-containing allele was present in 17% (17/101) of rhesus macaques (M. mulatta). The block to HIV-1 infection in lymphocytes from animals bearing the TRIM5-CypA allele was weaker than that in cells from wild type animals. HIV-1 infectivity remained significantly lower than SIV infectivity, but was not rescued by treatment with cyclosporine A. Thus, unlike owl monkey TRIMCyp, expression of the macaque TRIM5-CypA isoform does not result in increased restriction of HIV-1. Despite its distinct evolutionary origin, Macaca TRIM5-CypA has a similar domain arrangement and shares approximately 80% amino-acid identity with the TRIMCyp protein of owl monkeys. The independent appearance of TRIM5-CypA chimeras in two primate lineages constitutes a remarkable example of convergent evolution. Based on the presence of the CypA insertion in separate macaque lineages, and its absence from sooty mangabeys, we estimate that the Macaca TRIM5-CypA variant appeared 5-10 million years ago in a common ancestor of the Asian macaques. Whether the formation of novel genes through alternative splicing has played a wider role in the evolution of the TRIM family remains to be investigated.