Banca de QUALIFICAÇÃO: RICARDO VICTOR MACHADO DE ALMEIDA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : RICARDO VICTOR MACHADO DE ALMEIDA
DATA : 23/08/2019
HORA: 14:00
LOCAL: Sala Carl Peter von Dietrich - Departamento de Bioquímica
TÍTULO:

An insight into the origin and evolution of glyoxylate cycle enzymes in Viridiplantae

PALAVRAS-CHAVES:

Phylogeny, Malate synthase, Isocitrate lyase, Horizontal gene transfer (HGT), Arbuscular mycorrhizal fungi.

PÁGINAS: 1
GRANDE ÁREA: Ciências Biológicas
ÁREA: Bioquímica
RESUMO:

The glyoxylate cycle is a metabolic pathway located in plant glyoxysomes, which has a unique role in the establishment of the seedlings. Considered as a variation of the citric acid cycle this pathway can perform the liquid conversion of two molecules of acetyl-CoA to succinate, derived from lipid beta-oxidation to produce compounds used in the synthesis of carbohydrates. The enzymes Malate synthase (MLS) and Isocitrate lyase (ICL) are unique in this cycle and are essential in the regulation of carbohydrate biosynthesis. Due to the absence of the decarboxylation steps, as speed limiting factors, more detailed studies on the molecular evolution of these proteins may allow the clarification of the effects of the presence of this route on the evolutionary processes involved in plant species of oilseeds. However, it is widely accepted that the glyoxylate cycle also operates in bacteria and fungi, where they identified and characterized the presence of the genes of both enzymes, which apparently evolved through a horizontal transfer process. Since the emergence of this pathway, like others, was only possible due to different types of answers selection pressures to which plants were subject during the evolution and its establishment in the terrestrial environment. Therefore, the aims of this study were to investigate the emergence and establishment of the glyoxylate cycle and its relationship with the evolution of the enzymes Isocitrato lyase and Malate synthase in Viridiplantae. For this, we used the analysis approaches based on the distribution of the orthologous groups of the proteins belonging to this cycle in each species tree and the recognition of structural patterns in the evolution of the enzymes. Using the Geneplast package in R (v.3.4.1) comparisons were made between the dendrograms obtained by the implementation of a bridge algorithm to determine the evolutionary root of the cycle genes based on the distribution of their groups of orthologs. Phylogenetic reconstruction using BEAST and RAxML packages show that these copies were found only in some representatives of fungi (Glomerales), suggesting that they could have been spread out horizontally. Already the recognition of structural patterns in the evolution of the enzymes was done by prediction and homology modeling of the structures of the protein sequences obtained. Indeed, we find evidence of functional proteins derived from genes with conserved domains between plants and fungi, but the transfer directions for these genes could not be predicted yet. Therefore, the evolutionary consolidation of enzymes and the cycle in oilseed groups may have been induced by the induction of host genes involved in lipid metabolism in fungal groups.

MEMBROS DA BANCA:
Presidente - 1880243 - DANIEL CARLOS FERREIRA LANZA
Interna - 1453487 - KATIA CASTANHO SCORTECCI
Interno - 1507794 - RODRIGO JULIANI SIQUEIRA DALMOLIN