Unique properties of Zika NS2B-NS3pro complexes as decoded by experiments and MD simulations

Amrita Roy; Liangzhong Lim; Shagun Srivastava; Jianxing Song

The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/078113 doi: bioRxiv preprint 7 We also collected spectra of the intrinsic UV fluorescence from Trp residues for both linked and unlinked NS2B-NS3pro complexes (Fig. 2D) , both of which have similar spectra with the emission maxima at ~344 nm, very similar to what were observed on the NS2B-NS3pro complexes of all four Dengue serotypes (348 nm) (16) . This suggests that in Zika NS2B-NS3pro, all 4 Trp residues are similarly buried as Dengue ones, as Trp residue in the unfolded proteins has an emission maximum wavelength > 352 nm (24) . Strikingly, however, both linked and unlinked Zika NS2B-NS3pro complexes have far-UV CD spectra with the maximal negative signal at the wavelength of ~201 nm and is lacking of any positive signal below 200 nm, which is very different from that of unlinked Dengue one of the same length (12) , which has the maximal negative signal at 217 nm and large positive signal at 192 nm ( Fig. 2E ). This strongly suggests that Zika NS2B-NS3pro complexes contain much more disordered regions than the Dengue, completely consistent with the NMR HSQC result of the 15 N-labeled NS2B (Fig. 2C) . Unfortunately, the low solubility and µs-ms conformational dynamics prevented us from conducting NMR assignments of Zika NS2B-NS3pro by triple-resonance NMR experiments.