Hare TRIM5α Restricts Divergent Retroviruses and Exhibits Significant Sequence Variation from Closely Related Lagomorpha TRIM5 Genes

Abstract

TRIM5␣ proteins recruit and restrict incoming cytoplasmic retroviruses. Primate TRIM5␣ sequence diversity underlies species-specific restriction and is likely caused by selective pressure from ancient pathogenic infections. Here we show that TRIM5␣ from the European brown hare restricts diverse retroviruses. Furthermore, it differs significantly in sequence from TRIM5␣ from the closely related rabbit, suggesting evolutionary changes in the last 12 million years since these species diverged. We propose that, like primates, lagomorphs have been subject to selective pressure from TRIM5-sensitive viruses, possibly related to the endogenous lentivirus RELIK found in both rabbits and hares.TRIM5␣ proteins are cytoplasmic restriction factors (38) that are upregulated in response to viral infection (30, 32), bind to retroviral capsid protein (CA) (16,25,49), and inhibit retroviral infectivity in a species-specific way (31,42,48). TRIM5␣ belongs to the tripartite motif family of proteins, so named because of their RING-B-box-coiled-coil structure (RBCC), consisting of an N-terminal RING domain, often with E3 ubiquitin ligase activity (23), one or two B-box domains, and a coiled-coil (CC) domain.The TRIM5␣ isoform contains a C-terminal PRYSPRY domain, a ␤-sheet fold (46) whose nonstructured interconnecting loops, the "variable loops" v1, v2, v3, and v4, form the surfaces that make contact with retroviral CA (11,25,37). Residues in these loops contribute directly to primate TRIM5␣ species specificity (12,16,22) and have undergone strong positive selection during primate evolution (21,33,36). The sequence identity in the RBCC of primate TRIM5␣ orthologues between Old World monkeys (OWM), New World monkeys (NWM) and hominoids is high, but the sequence identity in the PRYSPRY is low, particularly in the variable loops (33,37,39). It is thought that this is due to differential exposures to TRIM5␣-sensitive pathogens since speciation (13,21,33,34). The identity of the pathogens applying selection pressure on TRIM5␣ is unclear, but the primate phylogeny suggests selection over long periods of time that predate lentiviruses (33). However, the difficulty in ageing retroviruses, and particularly lentiviruses, which do not appear to endogenize readily, makes it difficult to gauge whether they are old enough to have provided selection pressure on TRIM5␣. Recently, endogenous lentiviruses have been identified in rabbits, hares, and lemurs (5,6,14,15). RELIK, the lentivirus found in rabbits and hares, is at least 12 million years old (15). We previously identified a TRIM5␣ orthologue in rabbits (35), and in order to consider whether there has been adaptive change in Lagomorpha TRIM5␣ over the last 12 million years, we here identify and characterize an active TRIM5␣ from hares. We show that there are striking differences in the PRYSPRY sequences of rabbit and hare TRIM5␣s, suggesting adaptive change since these species split 12 million years ago.

TRIM 5α requires Ube2W to anchor Lys63‐linked ubiquitin chains and restrict reverse transcription

“…The strongest hits from the siRNA screen were validated by individually depleting Ube2W, Ube2N, and Ube2V2 from restrictive human TE671 cells using shRNA stably expressed from retroviral vectors (Fletcher et al , 2010). E2-depleted cells were infected with equivalent doses of N- or B-MLV, and viral DNA synthesis and infectivity were measured 6 and 48 h postinfection, respectively.…”

“…The Ube2V1 22mer sequence was previously described (Pertel et al , 2011). TE671 cells were transduced at an MOI ∼1 and selected in 2.5 μg/ml puromycin (Fletcher et al , 2010). …”

Ovine TRIM5α Can Restrict Visna/Maedi Virus

“…This interaction, involving amino acid 332 of TRIM5␣ in humans (15) and 334 in monkeys, may explain the high relative rates of nonsynonymous changes of the primate TRIM5␣ gene (13). TRIM5␣ has been described in primates and several mammals (3,6,30,33,41) but not in sheep or goats, both of which are infected by SRLV, their own lentivirus. This study aimed to identify and characterize the ovine and caprine TRIM5␣ proteins and explore the possible restrictive role of ovine TRIM5␣ on VMV infection.…”

Virus-Specific Effects of TRIM5α rh RING Domain Functions on Restriction of Retroviruses

“…In 2004, TRIM5␣ was identified as the major host factor that mediates this block (3). Since this discovery, the TRIM5 proteins of multiple mammalian species have been characterized, and the range of restricted viruses has expanded to include a variety of retroviruses (lentiviruses, a betaretrovirus, a gammaretrovirus, and spumaviruses) (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). A TRIM5 variant, TRIMCyp, which arose as a result of retrotransposition events involving TRIM5 and cyclophilin A, exhibits distinct restriction activities and has been identified in New World owl monkeys and some Old World macaque species (17)(18)(19)(20)(21)(22).…”