Estudo da interação entre o peptídeo de fusão da proteína E do vírus da Dengue com modelos de membrana biológica por simulações de dinâmica molecular.
Carregando...
Data
2018-08-31
Autores
Zonetti, Luiz Fernando da Costa
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Nas últimas décadas a Dengue se tornou a mais importante arbovirose a afetar o homem. A Dengue é causada por um tipo de flavivírus, que são vírus envelopados de geometria esférica. Hoje a Dengue é uma das doenças com maior incidência no Brasil, atingindo a população de todos os estados, independentemente de classe social. O vírus da Dengue possui um envelope viral composto por duas proteínas: a proteína E e a proteína M. A proteína E é considerada uma importante proteína viral, pois forma projeções na superfície do vírus e possui determinantes antigênicos para hemaglutinação e neutralização. A mesma possui uma sequência de resíduos de aminoácidos rica em resíduos hidrofóbicos e de glicinas chamada de peptídeo de fusão. O peptídeo de fusão está envolvido no processo de fusão do vírus com a membrana celular endossomal, necessário para a injeção do material genético viral no meio intracelular. A proteína E é glicolisada e forma homodímeros dispostos paralelamente à superfície viral em pH neutro, sendo incapaz de interagir com a membrana alvo. Com a exposição ao pH ácido do meio endossomal a proteína E sofre alteração conformacional que a leva para a conformação fusogênica, na qual o peptídeo de fusão está exposto. Independentemente da mudança estrutural sofrida pela glicoproteína viral durante este processo, seu peptídeo de fusão mantém a mesma conformação em pH neutro e ácido conforme evidenciado em estruturas cristalográficas. Neste trabalho investigamos a interação do peptídeo de fusão da proteína E do vírus da Dengue com bicamadas lipídicas, investigando a diferença de afinidade (energia livre de ligação) de duas sequências de resíduos de aminoácidos que contêm o peptídeo de fusão (resíduos 88-123 e 98- 110 retirados do PDBID: 1OAN) com dois modelos de membrana compostos por fosfolipídios POPC (Palmitoil-Oleil-Fosfatidil-Colina) e pela mistura de POPC e POPG (Palmitoil-Oleil-Fosfatidil-Glicerol) na proporção 4:1, utilizando simulações de dinâmica molecular e o método Adaptive Biasing Force (ABF). Nossos resultados indicam uma pequena diferença na energia livre de ligação de cada peptídeo com a bicamada de POPC e POPC com POPG e um pequeno deslocamento do enterramento do resíduo de triptofano, sendo que em ambas as bicamadas o enterramento está em acordo qualitativo com resultados experimentais obtidos por espectroscopia de fluorescência. Análises estruturais e da energética de ligação do peptídeo de fusão com as bicamadas estudadas apontam que ele não sofre alterações conformacionais significativas ao entrar na bicamada e que existe uma região, denominada de “colar” nesse trabalho, responsável pela maior parte das interações do peptídeo com as bicamadas, a qual pode ser alvo de futuros estudos na busca por inibidores do processo de infecção de células humanas pelo vírus da Dengue.
Dengue Fever is, nowadays, the most important arbovirosis to affect men. Dengue fever is caused by a flavivirus, enveloped viruses of spherical shape. Nowadays, it is one of the highest incidence diseases in Brazil, striking populations in every state regardless of social class. The Dengue virus presents a viral envelope composed of two proteins: E and M. Protein E is considered an important viral protein, because it forms projections on the surface of the virus and has antigenic determinants for hemagglutination and neutralization. Protein E holds a sequence of amino acids residue rich in hydrophobic residues and glycine called fusion peptide. The fusion peptide is involved in the process of the fusion of the virus with the endosomal cellular membrane important for the injection of viral genetic material into the intracellular medium. Protein E is glycosylated and forms homodimers parallel to the viral surface in neutral pH, being unable to interact with the target membrane. Due to exposure of acid pH of the endosomal medium, protein E undergoes conformational changes, leading to fusogenic conformation, where the fusion peptide is exposed. Regardless of the structural change undergone by the viral glycoprotein during this process, its fusion peptide keeps the same conformation in neutral and acid pH, as evidenced in crystallographic structures. In this study, we investigated the interaction of the fusion peptide of protein E of the Dengue virus with lipid bilayers calculating the difference in the affinity (binding free energy) of two sequences amino acids residue of the Protein E which contain the fusion peptide (residues 88-123 e 98-110 from PDBID: 1OAN) with two models membranes composed by phospholipids POPC (Palmitoil-Oleil-Fosfatidil-Colina) and by the mixture of POPC and POPG (Palmitoil-Oleil-Fosfatidil-Glicerol) in the ratio of 4:1, using Molecular Dynamics simulations the Adaptive Biasing Force (ABF) method. Our results show a small difference in the binding free energy of each peptide with the membrane POPC and POPC with POPG and a slight dislocation on the burial of the Tryptophan residue, showing that in both bilayers the burial is in qualitative agreement with experimental results obtained through fluorescence spectroscopy. Structural and energetic analyses of the binding of the fusion peptide with the studied bilayers show that it does not suffer significant conformational alterations when it enters the bilayers and that there is a region that we call “collar”, which is responsible by most of interactions between the fusion peptide with the bilayers, which can be the subject of future studies aiming at finding inhibitors to the infection of human cells by the Dengue virus.
Dengue Fever is, nowadays, the most important arbovirosis to affect men. Dengue fever is caused by a flavivirus, enveloped viruses of spherical shape. Nowadays, it is one of the highest incidence diseases in Brazil, striking populations in every state regardless of social class. The Dengue virus presents a viral envelope composed of two proteins: E and M. Protein E is considered an important viral protein, because it forms projections on the surface of the virus and has antigenic determinants for hemagglutination and neutralization. Protein E holds a sequence of amino acids residue rich in hydrophobic residues and glycine called fusion peptide. The fusion peptide is involved in the process of the fusion of the virus with the endosomal cellular membrane important for the injection of viral genetic material into the intracellular medium. Protein E is glycosylated and forms homodimers parallel to the viral surface in neutral pH, being unable to interact with the target membrane. Due to exposure of acid pH of the endosomal medium, protein E undergoes conformational changes, leading to fusogenic conformation, where the fusion peptide is exposed. Regardless of the structural change undergone by the viral glycoprotein during this process, its fusion peptide keeps the same conformation in neutral and acid pH, as evidenced in crystallographic structures. In this study, we investigated the interaction of the fusion peptide of protein E of the Dengue virus with lipid bilayers calculating the difference in the affinity (binding free energy) of two sequences amino acids residue of the Protein E which contain the fusion peptide (residues 88-123 e 98-110 from PDBID: 1OAN) with two models membranes composed by phospholipids POPC (Palmitoil-Oleil-Fosfatidil-Colina) and by the mixture of POPC and POPG (Palmitoil-Oleil-Fosfatidil-Glicerol) in the ratio of 4:1, using Molecular Dynamics simulations the Adaptive Biasing Force (ABF) method. Our results show a small difference in the binding free energy of each peptide with the membrane POPC and POPC with POPG and a slight dislocation on the burial of the Tryptophan residue, showing that in both bilayers the burial is in qualitative agreement with experimental results obtained through fluorescence spectroscopy. Structural and energetic analyses of the binding of the fusion peptide with the studied bilayers show that it does not suffer significant conformational alterations when it enters the bilayers and that there is a region that we call “collar”, which is responsible by most of interactions between the fusion peptide with the bilayers, which can be the subject of future studies aiming at finding inhibitors to the infection of human cells by the Dengue virus.
Descrição
Palavras-chave
Vírus da dengue, Peptídeo de fusão, Dinâmica molecular, Energia livre, Adaptive biasing force, Dengue virus, Fusion peptide, Molecular dynamics, Free energy