Banca de DEFESA: NATHALIA MAÍRA CABRAL DE MEDEIROS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : NATHALIA MAÍRA CABRAL DE MEDEIROS
DATA : 15/08/2018
HORA: 14:00
LOCAL: Sala Carl Peter von Dietrich - Departamento de Bioquímica
TÍTULO:

IDENTIFICATION AND CHARACTERIZATION FROM BASE EXCISION REPAIR PATHWAY COMPONENTS (BER) IN SUGARCANE (SACCHARUM spp.).

PALAVRAS-CHAVES:

DNA repair, AP Endonuclease, sugarcane, biochemical characterization, Phylogeny, Modeling

PÁGINAS: 326
GRANDE ÁREA: Ciências Biológicas
ÁREA: Bioquímica
SUBÁREA: Biologia Molecular
RESUMO:

The productivity of any cultivar is directly related to the stability of its genome. Then, if this genome suffers any damage or alteration in its sequence it can have consequences that can directly affect its development/growth. The response to DNA damage occurs through the repair that is achieved through different pathways, one of which is the base excision pathway (BER), whose studies in plants are based on Arabidopsis thaliana and rice. One of the obstacles in advancing research would be the complexity of the plant genome present in some cultivars of agroeconomic importance - such as sugarcane – because of this, many trials and studies use diploid model organisms. This work proposes to fill a gap in the knowledge of the BER in plants, especially for sugarcane. In a first work approach, a sequence homologous to the AP endonuclease of Arabidosis thaliana (AtARP) called the ScARP1 was used. This was the subject of an enzymatic characterization assay. The second approach was to identify and compare the different proteins associated to BER pathway in sugarcane and plants and evaluated its conservation, duplication. In order to make the first approach, the ScARP1 protein was cloned, expressed and purified. With th e protein purified different assays were done to evaluate its enzymatic efficiency (considering temperature, enzymatic cofactors and salt concentration), as well as the substrates that would be recognized by this enzyme. It was observed that ScARP1 only had AP endonuclease activity since it did not recognize other substrates with lesions. In addition, the existence of enzymatic complementation of ScARP1 in protein extracts from the Arabidopsis arp^-/- mutant was also examined. Partial complementation was observed. For the second approach of this work, it was considered the previous results, where a duplication in sugarcane was verified for the sequence AP endonuclease (ScARP1 and ScARP3), furthermore the recent work from the BER pathway in plants. Based on these data, a search was done on the sugarcane databases (SUCEST-FUN) for BER homology sequences in plants. The results obtained with this search were used for phylogenetic analyzes (via TaxOnTree) and Bayesian inferences (via BEAST v2.4.8) to verifying the occurrence of duplications on the BER components.The sequences found were characterized as the presence of conserved domains, besides some of them were modeled, creating hypothetical models. Some of the putative sugarcane proteins identified differ in their structure with the reference proteins of A. thalina, in addition to duplications were observed in some plant families except for others, indicating possible differences in the BER pathway mechanism. The results obtained with this work provided new information regarding characterization as well as the enzymatic characterization of the components of the BER pathway, increasing knowledge about this pathway in plant organisms.

MEMBROS DA BANCA:
Presidente - 1453487 - KATIA CASTANHO SCORTECCI
Externo ao Programa - 1813882 - ALICE DE MORAES CALVENTE VERSIEUX
Externo à Instituição - DAIANE CRISTINA FERREIRA GOLBERT - UFRN
Externo à Instituição - MARIE-ANNE VAN SLUYS - USP
Externo à Instituição - TERCILIO CALSA JUNIOR - UFPE