Deletion studies for elucidating the role of Streptomyces griseus ChiC non-catalytic residues
September 15-19, 2019
The soil bacterium, Streptomyces griseus, produces an antifungal chitinase (SgChiC) which has a smaller catalytic domain (in addition to a chitin binding domain) when compared with its counterparts from plants. Here, we carried out rational deletion of residues distant from the active site residues in the catalytic domain from 205 to 49 amino acid residues. The truncated residues were reconstructed and its 3-dimendional model predicted by homology modeling. In an insilico binding study, tri-N-acetyl glucosamine ((GlCNAc)3) was observed to bind to the active site of the truncated model similarly as in the wild type catalytic domain. This suggests that the variant model of SgChiC with a truncated catalytic domain possibly retains its chitinolytic properties. Further analysis of the simulation results revealed an increase in conformational space and flexibility of the reconstructed model over the less dynamic structure of the wild-type model. This suggests that the deleted residues played a role in the compactness and rigidity of the domain. Experimental assays to investigate the hydrolytic and kinetic properties of this truncated variant are currently been carried out. Outcomes of this study will reveal the relationship between the architecture of the ChiC domain and its function. This will guide future design studies for the enhancement of its functional properties and consequently its efficiency as a biocontrol agent.
Normi Mohd Yahaya, Adam Thean Chor Leow, Noor Baity Saidi, and Normi M. Yahaya, "Deletion studies for elucidating the role of Streptomyces griseus ChiC non-catalytic residues" in "Enzyme Engineering XXV", Huimin Zhao, University of Illinois at Urbana-Champaign, USA John Wong, Pfizer, USA Eds, ECI Symposium Series, (2019). https://dc.engconfintl.org/enzyme_xxv/3