Hybrid modeling of large targets
When modeling a large protein complex templates might be available just for some parts of it. During CASP14 this was the case for heteromeric targets H1060 and H1097. For both of these targets more accurate models were generated for those parts that had templates.
H1060 was a viral protein complex containing 27 subunits (5 homomeric rings bound to each other, A6B3C12D6, Fig. 4). We found templates for all the rings, and generated models of medium accuracy for all of them using either comparative modeling or template-based docking methods. Next, we tried to do template-based docking of the ring models to each other using another viral template, but for such a large complex the docking was complicated. As a result, the accuracy of hetero-complex (H1060v1) model is lower.
Similar situation was observed with hetero-pentamer H1097, where we tried to dock the domains of the 5th subunit to a homology model of a hetero-tetramer albeit with limited success (Supplementary Table S2).