Identification of substrates of an S-phase cell cycle kinase from Leishmania donovani.

Despite the importance of cyclin-Cdk related kinases (CRK) in regulation of cell and life cycle of kinetoplastida parasites, only limited knowledge about their substrates are presently available. Here, the potential substrates were searched for an S-phase LdCyc1-CRK3 complex from Leishmania donovani based on the presence of Cdk target phosphorylation site together with the cyclin interacting Cy-motif in genome-derived putative protein sequences. Three substrates could be identified with one of them being a unique protein with no known homologues. Another identified substrate is similar to MYST family of histone acetyl transferase and the third one contains Ku-70 related conserved domains. All the substrates interact directly with LdCyc1 and are phosphorylated in a Cy-motif dependent manner suggesting the importance of Cy-motif for their functions.