Biophysical Society Thematic Meeting| Lima 2019

Revisiting the Central Dogma of Molecular Biology at the Single-Molecule Level

Poster Abstracts

10-POS Board 10 STUDYING FOUR HUMAN HSP70 CHAPERONE MEMBERS USING SMALL ANGLE X-RAY SCATTERING (SAXS) Luiz Fernando de Camargo Rodrigues 1 ; Noeli S M da Silva 2 ; Paulo R Dores-Silva 2 ; Júlio C Borges 2 ; Leandro R S Barbosa 1 ; 1 Universidade de São Paulo, Institute of Physics, São Paulo, Brazil 2 Universidade de São Paulo, Institute of Chemistry of São Carlos, São Carlos, Brazil Molecular chaperones are responsible for proteostasis and cellular protein quality control, preventing misfolding and aggregation of client proteins, especially under stress conditions, also aiding in refolding processes, protein traffic, signalling and aggregates’ solubilization. They are known as Hsps (Heat Shock Proteins) and are intimately related to protein misfolding pathologies such as Parkinson and Alzheimer diseases and also some forms of cancer, being currently studied as potential drug targets. The Hsp70 family collaborate with cochaperones and nucleotide exchange factors to form a central component of the cellular chaperone machinery, having hundreds of client proteins, and are composed of a Nucleotide Binding Domain (NBD) and a Peptide Binding Domain (PBD) connected by a flexible linker. They present an ATP- dependent non-equilibrium mode of substrate binding that requires large domain rearrangements, which makes them suitable for Small Angle X-Ray Scattering (SAXS) experiments, as high resolution information is limited due to their dynamic nature and size. SAXS is a low resolution technique that provides general structural parameters, such as protein radius of gyration, maximum dimension and information on the particle shape. With such information, a low resolution three-dimensional model may be generated by means of computational methods. The objective of this study is to compare the structural modifications of the human Binding immunoglobulin protein (hBip), which is an Hsp70 homologue found in the endoplasmatic reticulum, by nucleotide binding and also to compare different human Hsp70 chaperones from different cell compartments and with varying sequence similarities. From the scattering profiles and analysis slight structural differences can be observed, which may be related to different client specificities, organelle environments and equilibrium properties with nucleotides.This work was supported by Conselho Nacional de Aperfeiçoamento de Pessoal de Nível Superior (PROEX - 0487), by FAPESP (17/26131-5) and by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).

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