Conformation and dynamics of the periplasmic membrane-protein-chaperone complexes OmpX-Skp and tOmpA-Skp.
The biogenesis of integral outer-membrane proteins (OMPs) in Gram-negative bacteria requires molecular chaperones that prevent the aggregation of OMP polypeptides in the aqueous periplasmic space. How these energy-independent chaperones interact with their substrates is not well understood. We have used high-resolution NMR spectroscopy to examine the conformation and dynamics of the Escherichia coli periplasmic chaperone Skp and two of its complexes with OMPs. The Skp trimer constitutes a flexible architectural scaffold that becomes more rigid upon substrate binding. The OMP substrates populate a dynamic conformational ensemble with structural interconversion rates on the submillisecond timescale. The global lifetime of the chaperone-substrate complex is seven orders of magnitude longer, emerging from the short local lifetimes by avidity. The dynamic state allows for energy-independent substrate release and provides a general paradigm for the conformation of OMP polypeptides bound to energy-independent chaperones.
Biozentrum, University of Basel, Basel, Switzerland.
Björn M
BM
Burmann
Congwei
C
Wang
Sebastian
S
Hiller
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D006867:Hydrolases / Q000737:chemistry* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D011487:Protein Conformation; D013997:Time Factors
D001425:Bacterial Outer Membrane Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; C072721:Skp protein, E coli; C482905:OmpX protein, E coli; C078167:OMPA outer membrane proteins; D006867:Hydrolases