ABSTRACT
Leucyl-tRNA synthetases (LRS) catalyze the linkage of leucine with tRNALeu. A large insertion CP1 domain(Connective Polypeptide 1) in LRS is responsible for post-transfer editing of mis-charged aminoacyl-tRNAs.Here, we characterized the CP1 domain of Leishmania donovani, a protozoan parasite, and its role in editingactivity and interaction with broad spectrum anti-fungal, AN2690. The deletion mutant of LRS, devoid of CP1domain (LRS-CP1D) was constructed, followed by determination of its role in editing and aminoacylation.Binding of AN2690 and different amino acids with CP1 deletion mutant and full length LRS was evaluatedusing isothermal titration calorimetry (ITC) and molecular dynamics simulations. The recombinant LRS-CP1Dprotein did not catalyze the aminoacylation and the editing reaction when compared to full-length LRS. Thus,indicating that CP1 domain was imperative for both aminoacylation and editing activities of LRS. Bindingstudies with different amino acids indicated selectivity of isoleucine by CP1 domain over other amino acids.These studies also indicated high affinity of AN2690 with the editing domain. Molecular docking studiesindicated that AN2690-CP1 domain complex was stabilized by hydrogen bonding and hydrophobic interactions resulting in high binding affinity between the two. Our data suggests CP1 is crucial for the function of L.donovani LRS.