Análise por modelagem e dinâmica molecular da interação entre a integrina α6β1 e a laminina 111 humana / Molecular modelling and dynamics analisys of human α6β1 integrin and laminin 111 interaction

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The extracelullar matrix (ECM) is formed by an assembly of proteins and glycoproteins which surrounds the cells, in various tissues. The laminin is a glycoprotein localized in the ECM that consists of three polypeptidic chains cross- shaped. It functions by anchoring epithelial cells to basal lamin, through associations with integrins, collagen, elastin and fibronectin. Integrins are adhesion receptors localized on cellular surface, that mediate interactions between cells and ECM. The interactions between proteins of ECM and cellular proteins are crucial for many normal biological processes such as cell differentiation, signal transduction, immune responses, wound healing and metastasis formation. The nature of interactions between laminin and integrin has not been fully identified yet. The present work aims to analyze, in an molecular scale, the interaction between human α6β1 integrin and laminin 111. In this work we conducted many studies, including: i) structural and sequential alignments of β-propeller and βA regions in lacking I-domain integrins; ii) model building of β-propeller e βA regions of α6β1 integrin complexed with small ECD or RGD peptide antagonists; iii) sequential alignment of various laminin LG domains; iv) model building of laminin 111 LG1 domain; and v) model building of the first described complex between the N-terminal portion of α6β1 integrin and laminin 111 LG1 domain. In order to do this, homology modeling and molecular dynamics techniques were applied, together with alignments between integrins α and β chains, and laminin LG domains. Our initial results show that the loop between blades 3 and 4 of α6 integrin subunit discriminates ligands by electrostatic interactions. Therefore we assumed that α6β1 integrin preferentially interacts with ECDF based peptides. It was demonstrated that the laminin 111 LG1 domain interacts with α6β1 integrin by the contact of this H β strand and α6 β-propeller. Further, by its electrostatic function and proximity to H β strand, LG1 residue Asp82 adheres to Mg+2 containing MIDAS in α6β1 integrin. This interaction appears to be indispensable for α6β1 and laminin 111 binding.

ASSUNTO(S)

molecular structure biologia molecular laminina integrin integrina laminin estrutura molecular

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