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From Constructs to Crystals – Towards Structure Determination of β-barrel Outer Membrane Proteins
Published on: July 4, 2016
Assembly of bacterial inner membrane proteins
Ross E Dalbey1, Peng Wang, Andreas Kuhn
1The Ohio State University, Department of Chemistry, Columbus, Ohio 43210. Dalbey@chemistry.ohio-state.edu
Annual Review of Biochemistry
|February 1, 2011
Summary
Bacterial membrane proteins assemble into complexes through specific insertion and folding pathways. Quality control mechanisms ensure proper folding and assembly, degrading misfolded or misassembled proteins.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Membrane proteins are crucial for cellular functions and often exist as multisubunit complexes.
- Bacterial membrane protein insertion involves the Sec translocase and YidC insertase, with phospholipids like phosphatidylethanolamine (PE) aiding folding.
- Transmembrane helix interactions, mediated by motifs like glycine zippers, are vital for forming alpha-helical bundles.
Purpose of the Study:
- To elucidate the assembly pathways of multisubunit bacterial membrane protein complexes.
- To understand the roles of insertion machinery, folding facilitators, and specific motifs in protein complex formation.
- To investigate the quality control mechanisms governing membrane protein folding and assembly.
Main Methods:
- Analysis of protein insertion mechanisms using Sec translocase and YidC insertase.
- Investigating the role of phospholipids (PE) and protein motifs (glycine zippers) in folding and helix interactions.
- Studying the assembly process of homo- and hetero-oligomeric membrane protein complexes.
- Examining cellular quality control pathways for misfolded or misassembled membrane proteins.
Main Results:
- Membrane protein folding is facilitated by YidC and phosphatidylethanolamine (PE).
- Specific motifs promote transmembrane helix interactions, leading to alpha-helical bundle formation.
- Subunits of hetero-oligomeric complexes typically assemble sequentially.
- Quality control mechanisms effectively degrade misfolded or misassembled membrane proteins.
Conclusions:
- Bacterial membrane protein complex assembly is a multi-step process involving insertion, folding, and subunit association.
- Spontaneous folding and oligomerization occur, but specific pathways and quality control are essential for functional complex formation.
- Understanding these processes is key to comprehending membrane protein function and cellular integrity.
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