Structural features and interactions between transmembrane and juxtamembrane domains in membrane proteins

• Main Author: Surya, Wahyu
• Other Authors: Jaume Torres
• Format: Theses and Dissertations
• Language: English
• Published: 2017
• Subjects: DRNTU::Science::Biological sciences::Biophysics
• Online Access: http://hdl.handle.net/10356/69964
• Institution: Nanyang Technological University

Reconstitution environment plays an important role in structural determination of membrane proteins. The present study explores this theme in two systems: (1) the TM domain of integrin αL/β2, a single-pass integral membrane protein that heterodimerizes in α/β pairs, and (2) CoV E protein, a single-pass integral membrane protein that forms homopentameric ion channels. Monomeric and oligomeric structural models for integrin αL/β2 and E protein were determined by solution NMR. The model of αL/β2 TM heterodimer determined herein supports the "backbone reversal" structural feature previously observed only in αIIb/β3 TM in bicelles, instead of an α-helix observed in the presence of micelles or organic solvent. Yet, it is possible that the two forms reflect different activation states of integrin. Monomeric model for CoV E protein revealed conformational flexibility with functional relevance at the C-terminal extramembrane domain. The pentameric model offered possible explanations for the ion channel activity of E protein. In both systems, we found that the alternate forms observed under different reconstitution environment may reflect alternative conformation with functional relevance.