FIGURE 2. The HIT-like fold in NSP2.

a, The region of the NSP2 structure which shows the HIT-like fold (above), along with a topology diagram (below). b, Corresponding domain in the PKCI (PDB entry code: 1KPF) structure (above), along with the topology diagram (below). The HIT fold typically has 32 configuration. The three His residues of the triad in the PKCI, and two of the histidines in NSP2 are also shown. Structural similarity was discovered using the DALI server¹⁹, which indicated statistically significant (Z-scores > 3.6) homology with three of the HIT proteins. The r.m.s. deviation in the matching C atoms ranged from 2.3 to 3.3 Å for these HIT proteins. The PKCI protein, despite having a lower r.m.s. value (3.3 Å for matching 71 C atoms), had a higher Z-score (4.2).