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Replication origins in trypanosomes

Grant number: 14/13375-5
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): August 01, 2014
Effective date (End): June 30, 2018
Field of knowledge:Biological Sciences - Parasitology - Protozoology of Parasites
Principal researcher:Maria Carolina Quartim Barbosa Elias Sabbaga
Grantee:Christiane Bezerra de Araujo
Home Institution: Instituto Butantan. Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil
Associated research grant:13/07467-1 - CeTICS - Center of Toxins, Immune-Response and Cell Signaling, AP.CEPID


REPLICATION ORIGINS IN TRYPANOSOMES Ph1(1-2):Replication origins in trypanosomes and their position into nucleosomes during T.cruzi life cycle Chromosomal replication initiates with the assembly of the pre-replication complex(pre-RC) at DNA sites along the chromosomes that are called origins of replication1. The genomes of the majority of eukaryotic cells are replicated from many replication origins during the synthetic (S) phase of the cell cycle. This process requires that cells must ensure that sufficient numbers of origins are used in each S phase without the reuse of any origin in a single cell cycle. Unlike other eukaryotes, little is known about the DNA replication process in trypanosomes, protozoan parasites that appear early in the evolution. Using high throughput analysis of nascent DNA strand, this project intends to identify replication origins in T.cruzi and T.brucei, etiological agents of Chagas' and Sleeping Sickness diseases, respectively. Some obtained sequences will be checked as indeed replication origins using SMARD and ChIP assays. Ph2(3-4): Replication origins in trypanosomes and their position into nucleosomes during T.cruzi life cycle. The life cycle of T.cruzi alternates between replicative and non-replicative stages. The molecular bases that control the lack of DNA replication in non-replicative stages remain to be determined. It has already been showed that in eukaryotes replication origins are located in non-nucleosomal regions. Therefore, once identified replication origins in T.cruzi, we intend to investigate how these sequences are organized,concerning nucleosomal position, in different stages of T.cruzi life cycle. In this way, genomic DNAs will be digested with nuclease micrococcus, that digests all nucleosomal-free DNA, and nucleosomal protected DNA will be sequenced. Ph3(5): Characterization of trypanosomes DNA pre-replication machinery Chromosomal replication initiates with the assembly of the pre-replication complex (pre-RC) at DNA sites along the chromosomes that are called origins of replication1. In eukaryotes, the pre-RC is composed of an origin recognition complex (ORC) containing the Orc1-Orc6 molecules, two proteins named Cdc6 and Cdt1, and the mini-chromosome maintenance(MCM) complex, which is composed of Mcm2-Mcm7 molecules. As long as the pre-RC composed of ORC1-6, Cdc6, Cdt1, and MCM2-7 is organized on the chromatin, origins become licensed to replicate. In addition, other proteins must associate with the origin prior to the successful initiation of DNA synthesis. The binding of regulatory factors and components of the replication fork to DNA allows origin unwinding,the recruitment of replicative DNA polymerases, and finally the establishment of replication fork 2,3. Unlike other eukaryotes, little is known about the DNA replication process in trypanosomes, protozoan parasites that appear early in the evolution. As trypanosomatids have peculiar characteristics, with their genes transcribed in polycistronic units and processed by a trans-splicing reaction, and with gene expression controlled mainly at the post-transcriptional level4-6, we hypothesize that new strategies to deal with the regulation of replication can be found in these organisms. Genomic databases of trypanosomatids show that these organisms contain all MCM molecules, but they do not contain sequences in their genome that could code for the ORC subunits, Cdc6, or Cdt1. Trypanosomes have a gene for only 1 of the 6 subunits of the ORC, Orc1, which is also homologous to Cdc6. It is annotated as Orc17 and we named it Orc1/Cdc6. Previous results from our group showed that Orc1/Cdc6 is indeed a pre-replication machinery component that might be involved in the selection of replication origins in these organisms8. Using genetic reverse techniques (RNAi, expression of tag proteins), and conventional molecular and cellular assays, we intend to (i) search for molecules that could be components of the pre-replication machinery and/or (ii) understand how is the recruitment of MCM helicase complex directly by Orc1/Cdc6.

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Scientific publications (7)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
MARIN, PAULA ANDREA; OBONAGA, RICARDO; PAVANI, RAPHAEL SOUZA; DA SILVA, MARCELO SANTOS; DE ARAUJO, CHRISTIANE BEZERRA; LIMA, ANDRE ARRUDA; AVILA, CARLA CRISTI; CESTARI, IGOR; MACHADO, CARLOS RENATO; ELIAS, MARIA CAROLINA. ATR Kinase Is a Crucial Player Mediating the DNA Damage Response in Trypanosoma brucei. FRONTIERS IN CELL AND DEVELOPMENTAL BIOLOGY, v. 8, . (17/18719-2, 18/12364-0, 15/10580-0, 14/02978-0, 14/24170-5, 19/01895-8, 16/50050-2, 14/13375-5)
DE ARAUJO, CHRISTIANE BEZERRA; CHAGAS DA CUNHA, JULIA PINHEIRO; INADA, DAVI TOSHIO; DAMASCENO, JEZIEL; JERONIMO LIMA, ALEX RANIERI; HIRAIWA, PRISCILA; MARQUES, CATARINA; GONCALVES, EVONNILDO; NISHIYAMA-JUNIOR, MILTON YUTAKA; MCCULLOCH, RICHARD; et al. Replication origin location might contribute to genetic variability in Trypanosoma cruzi. BMC Genomics, v. 21, n. 1, . (13/07467-1, 14/24170-5, 16/50050-2, 14/13375-5)
DE ARAUJO, CHRISTIANE BEZERRA; DE LIMA, LOYZE PAOLA; CALDERANO, SIMONE GUEDES; DAMASCENO, FLAVIA SILVA; SILBER, ARIEL M.; ELIAS, MARIA CAROLINA. Pep5, a Fragment of Cyclin D2, Shows Antiparasitic Effects in Different Stages of the Trypanosoma cruzi Life Cycle and Blocks Parasite Infectivity. Antimicrobial Agents and Chemotherapy, v. 63, n. 5, . (14/13375-5, 16/50050-2, 17/16553-0, 13/07467-1, 16/06034-2)
DA SILVA, MARCELO S.; CAYRES-SILVA, GUSTAVO R.; VITARELLI, MARCELA O.; MARIN, PAULA A.; HIRAIWA, PRISCILA M.; ARAUJO, CHRISTIANE B.; SCHOLL, BRUNO B.; AVILA, ANDREA R.; MCCULLOCH, RICHARD; REIS, MARCELO S.; et al. Transcription activity contributes to the firing of non-constitutive origins in African trypanosomes helping to maintain robustness in S-phase duration. SCIENTIFIC REPORTS, v. 9, . (15/10580-0, 17/07693-2, 17/18719-2, 16/17775-3, 14/24170-5, 16/50050-2, 13/07467-1, 14/13375-5)
DE LIMA, LOYZE P.; CALDERANO, SIMONE G.; DA SILVA, MARCELO S.; DE ARAUJO, CHRISTIANE B.; VASCONCELOS, ELTON J. R.; IWAI, LEO K.; PEREIRA, CLAUDIO A.; FRAGOSO, STENIO P.; CAROLINA ELIAS, M.. Ortholog of the polymerase theta helicase domain modulates DNA replication in Trypanosoma cruzi. SCIENTIFIC REPORTS, v. 9, . (14/24170-5, 13/07467-1, 16/50050-2, 14/13375-5)
PAVANI, RAPHAEL SOUZA; DA SILVA, MARCELO SANTOS; HENRIQUE FERNANDES, CARLOS ALEXANDRE; MORINI, FLAVIA SOUZA; ARAUJO, CHRISTIANE BEZERRA; DE MATTOS FONTES, MARCOS ROBERTO; SANT'ANNA, OSVALDO AUGUSTO; MACHADO, CARLOS RENATO; CANO, MARIA ISABEL; FRAGOSO, STENIO PERDIGAO; et al. Replication Protein A Presents Canonical Functions and Is Also Involved in the Differentiation Capacity of Trypanosoma cruzi. PLoS Neglected Tropical Diseases, v. 10, n. 12, . (14/13375-5, 14/24170-5, 13/17864-8, 14/02978-0, 13/07467-1, 15/10580-0)
DE ARAUJO, CHRISTIANE B.; CALDERANO, SIMONE G.; ELIAS, MARIA CAROLINA. The Dynamics of Replication in Trypanosoma cruzi Parasites by Single-Molecule Analysis. Journal of Eukaryotic Microbiology, v. 66, n. 3, p. 514-518, . (13/07467-1, 16/50050-2, 14/13375-5)

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