title: Evolution of a TRIM5-CypA splice isoform in old world monkeys.
abstract: 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.
authors.affiliation: Department of Microbiology and Molecular Genetics, New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts, United States of America.
authors.forename: Ruchi M
authors.initials: RM
authors.lastname: Newman
authors.forename: Laura
authors.initials: L
authors.lastname: Hall
authors.forename: Andrea
authors.initials: A
authors.lastname: Kirmaier
authors.forename: Lu-Ann
authors.initials: LA
authors.lastname: Pozzi
authors.forename: Erez
authors.initials: E
authors.lastname: Pery
authors.forename: Michael
authors.initials: M
authors.lastname: Farzan
authors.forename: Shawn P
authors.initials: SP
authors.lastname: O'Neil
authors.forename: Welkin
authors.initials: W
authors.lastname: Johnson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002520:Cercopithecidae; D021984:Cyclophilin A / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D005838:Genotype; D015658:HIV Infections / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D015497:HIV-1; D006720:Homozygote; D007113:Immunity, Innate; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D008992:Monkey Diseases / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D050506:Mutant Chimeric Proteins / Q000235:genetics; D010835:Phytohemagglutinins / Q000494:pharmacology; D020641:Polymorphism, Single Nucleotide; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases
chemical_list: D050506:Mutant Chimeric Proteins; D010835:Phytohemagglutinins; D020033:Protein Isoforms; D011506:Proteins; C482587:TRIM5(alpha) protein, rhesus monkey; D044767:Ubiquitin-Protein Ligases; D021984:Cyclophilin A