Fig. 3

Binding affinity of different signal sequences with SRP54M subunit and antigen expression levels of mRNA vaccines modified by different signal sequences. (A) Coding sequences (CDSs) of mRNA with different signal sequences (SS) employed in the study. (B) The affinity and paired energy of signal sequences with the SRP54M domain calculated by computational simulation. 2D eyelash chart and 3D dominant binding conformation of SRP54M subunit to the signal peptides of (C) origin, (D) tPA, and (E) IL-6 by computational simulation. As showed in the 2D diagram, the dashed line indicated hydrogen bonding, and the number next to it indicated the hydrogen bond length. The remaining eyelashes-like residues represented hydrophobic interactions, where the eyelashes pointed towards the key residues that produced hydrophobic interactions. The 3D diagram showed the overall and local conformation of the signal peptides binding with SRP54M subunit. Intracellular and culture supernatant RBD expression levels of the different signal sequence-modified RBD^WT mRNA transfected (F) DC2.4 and (G) 293T cells. The results were presented as the mean ± SEM, n = 3. ^*P < 0.05, ^**P < 0.01, ^***P < 0.001