Open AccessFolding Determinants of Transmembrane β-Barrels Using Engineered OMP Chimeras
Author(s) -
Deepti Chaturvedi,
Radhakrishnan Mahalakshmi
Publication year - 2018
Publication title -
biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.43
H-Index - 253
eISSN - 1520-4995
pISSN - 0006-2960
DOI - 10.1021/acs.biochem.8b00012
Subject(s) - protein engineering , barrel (horology) , transmembrane protein , yersinia pestis , chemistry , nanopore , biophysics , folding (dsp implementation) , bama , scaffold , protein folding , computational biology , nanotechnology , bacterial outer membrane , escherichia coli , biology , biochemistry , materials science , computer science , receptor , engineering , virulence , electrical engineering , composite material , gene , enzyme , database
Transmembrane β-barrel proteins (OMPs) are highly robust structures for engineering and development of nanopore channels, surface biosensors, and display libraries. Expanding the applications of designed OMPs requires the identification of elements essential for β-barrel scaffold formation and stability. Here, we have designed chimeric 8-stranded OMPs composed of strand hybrids of Escherichia coli OmpX and Yersinia pestis Ail, and identified molecular motifs essential for β-barrel scaffold formation. For the OmpX/Ail chimeras, we find that the central hairpin strands β4-β5 in tandem are vital for β-barrel folding. We also show that the central hairpin can facilitate OMP assembly even when present as the N- or C-terminal strands. Further, the C-terminal β-signal and strand length are important but neither sufficient nor mutually exclusive for β-barrel assembly. Our results point to a nonstochastic model for assembly of chimeric β-barrels in lipidic micelles. The assembly likely follows a predefined nucleation at the central hairpin only when presented in tandem, with some influence from its absolute position in the barrel. Our findings can lead to the design of engineered barrels that retain the OMP assembly elements necessary to attain well-folded, stable, yet malleable scaffolds, for bionanotechnology applications.