Folding Determinants of Transmembrane β-Barrels Using Engineered OMP Chimeras

Area of Science:

• Structural biology
• Protein engineering
• Bionanotechnology

Background:

• Transmembrane β-barrel proteins (OMPs) are versatile scaffolds for applications like nanopore channels and biosensors.
• Engineering novel OMP applications necessitates identifying key elements for β-barrel formation and stability.

Purpose of the Study:

• To identify molecular motifs essential for the formation and stability of engineered β-barrel scaffolds.
• To investigate the role of specific structural elements in the assembly of chimeric OMPs.

Main Methods:

• Design and construction of chimeric 8-stranded OMPs using strand hybrids of Escherichia coli OmpX and Yersinia pestis Ail.
• Analysis of β-barrel folding and assembly mechanisms in lipidic micelles.

Main Results:

• The central hairpin strands (β4-β5) are vital for β-barrel folding and can facilitate assembly even when positioned at the termini.
• C-terminal signals and strand length influence assembly but are not solely sufficient or exclusive.
• A nonstochastic, nucleation-dependent assembly model is proposed, centered on the tandem hairpin.

Conclusions:

• The central hairpin motif is a critical determinant for OMP β-barrel assembly.
• Findings provide insights into designing stable, malleable OMP scaffolds for advanced bionanotechnology applications.