Abstract
BackgroundThe TRIM family is composed of multi-domain proteins that display the Tripartite Motif (RING, B-box and Coiled-coil) that can be associated with a C-terminal domain. TRIM genes are involved in ubiquitylation and are implicated in a variety of human pathologies, from Mendelian inherited disorders to cancer, and are also involved in cellular response to viral infection.ResultsHere we defined the entire human TRIM family and also identified the TRIM sets of other vertebrate (mouse, rat, dog, cow, chicken, tetraodon, and zebrafish) and invertebrate species (fruitfly, worm, and ciona). By means of comparative analyses we found that, after assembly of the tripartite motif in an early metazoan ancestor, few types of C-terminal domains have been associated with this module during evolution and that an important increase in TRIM number occurred in vertebrate species concomitantly with the addition of the SPRY domain. We showed that the human TRIM family is split into two groups that differ in domain structure, genomic organization and evolutionary properties. Group 1 members present a variety of C-terminal domains, are highly conserved among vertebrate species, and are represented in invertebrates. Conversely, group 2 is absent in invertebrates, is characterized by the presence of a C-terminal SPRY domain and presents unique sets of genes in each mammal examined. The generation of independent sets of group 2 genes is also evident in the other vertebrate species. Comparing the murine and human TRIM sets, we found that group 1 and 2 genes evolve at different speeds and are subject to different selective pressures.ConclusionWe found that the TRIM family is composed of two groups of genes with distinct evolutionary properties. Group 2 is younger, highly dynamic, and might act as a reservoir to develop novel TRIM functions. Since some group 2 genes are implicated in innate immune response, their evolutionary features may account for species-specific battles against viral infection.
Highlights
The TRIM family is composed of multi-domain proteins that display the Tripartite Motif (RING, B-box and Coiled-coil) that can be associated with a C-terminal domain
By means of comparative analyses we found that, after assembly of the tripartite motif in an early metazoan ancestor, few types of C-terminal domains have been associated with this module during evolution and that an important increase in TRIM number occurred in vertebrate species concomitantly with the addition of the SPRY domain
We showed that the human TRIM family is split into two groups that differ in domain structure, genomic organization and evolutionary properties
Summary
The TRIM family is composed of multi-domain proteins that display the Tripartite Motif (RING, B-box and Coiled-coil) that can be associated with a C-terminal domain. Different C-terminal domains are associated with the tripartite motif in the TRIM family [1,2,3,4] Both RING and B-boxes are cysteine-rich zinc-binding domains. A limited choice of C-terminal domains is found in association with the tripartite motif and determined the recent classification of the TRIM proteins in subfamilies [4]. This conserved multi-domain structure appears to behave as an integrated module, rather than a collection of separate motifs, suggesting a possible common function [1,6]
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