Comparative Structural Analysis of the SCF E3 Ligase Component Hrt1p and its Mutant (C81Y) of S.cerevisiae by Homology Modelling

The ubiquitin proteasome degradation mechanism (UPS) is one of the finest cellular processes which are essential in driving biological processes in the unidirectional manner such as cell division, DNA replication, and DNA repair. The mechanism ensures that the proteins recycling are achieved efficiently after attaining the crucial function. The UPS involved the marking of the proteins by Ub (71 AA residue chain) ligation and channelizing into the 26S proteasome for degradation. The tagging of target protein is achieved by sequential reaction by the E1, E2, E3 ligases where E3 ligase recruits the target protein for marked destruction. The Hrt1 protein of the S. cerevisiae is the catalytic subunit of the SKP1-Cul-Fbox E3 ligase (SCF) and essential in nature. Here in this study we carried out the 3D structure prediction analysis of the Hrt1p and one of its mutants (C81Y), defective in substrate recruitment, by homology modelling. We report that WT Hrt1p and mutant Hrt1p (C81Y) differs in their structural aspect of alpha helix and -sheets, which might explain the functional heterogeneity in the WT and mutant.