Mechanistic Role of TRIM26 in Viral Infection and Host Defense

Figure 1. TRIMs derived from Suf Scrofa (pigs) structures. TRIM sequences from pigs were examined and potential domains were inferred. TRIMs from pigs have a conservative N-terminal. The C-terminal, on the other hand, has a range of variable domains.

Figure 2. Phylogenetic analysis of TRIM26 depicting sequence divergences between different species. The amino acid sequences of 78 different species and porcine TRIM26 were compared using MEGA 11. Homologies above 90%, 80%, 70%, and 20% are shown above.

Figure 3. Predicted structural similarity between porcine TRIM26 and TRIM26 of Homo sapiens and Pan troglodytes. Porcine TRIM26 is shown by the color red, while Homo sapiens and Pan troglodytes TRIM26 are indicated by the color pale pink.

Figure 4. RING domain and B-Box domain comparsion of TRIM26 of Sus scrofa with 10 other species. ‘*’ shows a highly conserved residue, ‘:’ shows a residue that shares some similar biochemical properties, and ‘.’ shows little similarity between the aligned sequences.

Figure 5. SPRY domain comparison of TRIM26 of Sus scrofa with 10 other species. ‘*’ shows a highly conserved residue, ‘:’ shows a residue that shares some similar biochemical properties, and ‘.’ shows little similarity between the aligned sequences.

Figure 6. Overview of TRIM26 function. (A) E3 ligase ubiquitin, a tiny protein with 76 amino acids that is highly conserved in eukaryotic species, is a part of the structure of TRIM26. One of the seven lysine (K) residues on target proteins, such as 48 or 63, can be linked to E1 ubiquitin, which functions as a flag for endocytosis, DNA repair, and enzymatic activation, in addition to proteasome-mediated destruction. (B) The conjugation reaction of ubiquitin is catalyzed by the E1 ubiquitin-activating enzyme, E2 ubiquitin-conjugating enzymes, and E3 ubiquitin ligases. (C) E3 functions as a scaffold that mediates between E2 and the substrate, which is in charge of substrate recognition. This is the biochemical reaction of the ubiquitin proteasome activity. The 26S proteasome then finds the resultant polyubiquitinated conjugates and quickly breaks them down.

Figure 7. TRIM26 functions as a suppressor of immune responses during a viral infection. The ubiquitination of IRF3 or its upstream sensors by TRIM26 results in immune suppression during viral infection. Ultimately, the replication of viruses, such as HSV-2, PRV, SEV, VSV, HBV, HCV, and PRRSV, is facilitated in a TRIM26-dependent manner.

Figure 8. TRIM26 exerts a beneficial impact on the host immune responses during a viral infection. TRIM26 displays versatile roles across different viral infections, modulating the regulation of type I IFN during diverse viral challenges.