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Publication Abstract from PubMed

Proliferating cell nuclear antigen (PCNA) acts as a sliding clamp to support DNA replication and repair. The structure of PCNA from Leishmania donovani (LdPCNA) has been determined at 2.73A resolution. Structure consists of six crystallographically independent molecules which form two trimeric rings. The pore diameter of the individual trimeric ring is of the order of 37A. The two rings are stacked through their front to front faces. In order to gain a stable packing, the rings are rotated by 42 degrees about the pore axis and shifted by 7A and tilted by 16 degrees along the perpendicular direction to pore axis. This form of stacking reduced the effective diameter of the pore to 32A. The sequence of LdPCNA consists of a long segment of 41 amino acid residues (186-Gly-Val-Ser-Asp-Arg-Ser-Thr-Lys-Ser-Glu-Val-Lys-Ala-Glu-Val-Lys-Ala-Glu-Ala- Arg-Asp-Asp-Asp-Glu-Glu-Pro-Leu-Ser-Arg-Lys-Tyr-Gly-Lys-Ala-Asp-Ser-Ser-Ala-Asn-A la-Ile-226) whereas the corresponding segments in other PCNAs contain only eight residues corresponding to 186-Gly-Val-Ser-Asp-Arg------224-Asn-Ala-Ile-226. The enhanced length of this segment in LdPCNA may influence its mode of interaction with DNA and other proteins. The dissociation constants obtained using real time binding studies with surface plasmon resonance (SPR) for two peptides, Lys-Arg-Arg-Gln-Thr-Ser-Met-Thr-Asp-Phe-Tyr-His (P1) from human cyclin-dependent kinase inhibitor-1(CKI-1) and Lys-Thr-Gln-Gly-Arg-Leu-Asp-Ser-Phe-Phe-Thr-Val (P2) from flap endonuclease 1 (Fen-1) as well as with two small molecule inhibitors, (S)-4-(4-(2-amino-3-hydroxypropyl)-2, 6-diiodophenoxy) phenol hydrochloride (ADPH) and N-(3-methylthiophene-2-carboxylicacid)-N'-((3-hydroxy-2-naphthalenyl) methylene) hydrazide (MCMH) are 0.29+/-0.09muM, 0.37+/-0.08muM, 0.35+/-0.09muM and 1.20+/-0.08muM respectively. The corresponding values obtained using fluorescence spectroscopic methods were 0.22+/-0.06muM, 0.68+/-0.07muM, 0.44+/-0.07muM and 0.75+/-0.05muM respectively.

Structure and binding studies of proliferating cell nuclear antigen from Leishmania donovani.,Yadav SP, Singh PK, Sharma P, Iqbal N, Kaur P, Sharma S, Singh TP Biochim Biophys Acta. 2017 Nov;1865(11 Pt A):1395-1405. doi:, 10.1016/j.bbapap.2017.08.011. Epub 2017 Aug 24. PMID:28844736^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.