title: The distribution pattern of proliferating cell nuclear antigen in the nuclei of Leishmania donovani.
abstract: DNA replication in eukaryotes is a highly conserved process marked by the licensing of multiple origins, with pre-replication complex assembly in G1 phase, followed by the onset of replication at these origins in S phase. The two strands replicate by different mechanisms, and DNA synthesis is brought about by the activity of the replicative DNA polymerases Pol delta and Pol epsilon. Proliferating cell nuclear antigen (PCNA) augments the processivity of these polymerases by serving as a DNA sliding clamp protein. This study reports the cloning of PCNA from the protozoan Leishmania donovani, which is the causative agent of the systemic disease visceral leishmaniasis. PCNA was demonstrated to be robustly expressed in actively proliferating L. donovani promastigotes. We found that the protein was present primarily in the nucleus throughout the cell cycle, and it was found in both proliferating procyclic and metacyclic promastigotes. However, levels of expression of PCNA varied through cell cycle progression, with maximum expression evident in G1 and S phases. The subnuclear pattern of expression of PCNA differed in different stages of the cell cycle; it formed distinct subnuclear foci in S phase, while it was distributed in a more diffuse pattern in G2/M phase and post-mitotic phase cells. These subnuclear foci are the sites of active DNA replication, suggesting that replication factories exist in Leishmania, as they do in higher eukaryotes, thus opening avenues for investigating other Leishmania proteins that are involved in DNA replication as part of these replication factories.
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India.
authors.forename: Devanand
authors.initials: D
authors.lastname: Kumar
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India.
authors.forename: Neha
authors.initials: N
authors.lastname: Minocha
authors.affiliation: National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India.
authors.forename: Kalpana
authors.initials: K
authors.lastname: Rajanala
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India.
authors.forename: Swati
authors.initials: S
authors.lastname: Saha
mesh_terms: D000595:Amino Acid Sequence; D002453:Cell Cycle; D002467:Cell Nucleus / Q000378:metabolism*; D003001:Cloning, Molecular; D004261:DNA Replication; D016054:DNA, Protozoan / Q000096:biosynthesis; D007893:Leishmania donovani / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D016054:DNA, Protozoan; D018809:Proliferating Cell Nuclear Antigen