Crystal structure of Skp, a prefoldin-like chaperone that protects soluble and membrane proteins from aggregation.
The Seventeen Kilodalton Protein (Skp) is a trimeric periplasmic chaperone that assists outer membrane proteins in their folding and insertion into membranes. Here we report the crystal structure of Skp from E. coli. The structure of the Skp trimer resembles a jellyfish with alpha-helical tentacles protruding from a beta barrel body defining a central cavity. The architecture of Skp is unexpectedly similar to that of Prefoldin/GimC, a cytosolic chaperone present in eukaria and archea, that binds unfolded substrates in its central cavity. The ability of Skp to prevent the aggregation of model substrates in vitro is independent of ATP. Skp can interact directly with membrane lipids and lipopolysaccharide (LPS). These interactions are needed for efficient Skp-assisted folding of membrane proteins. We have identified a putative LPS binding site on the outer surface of Skp and propose a model for unfolded substrate binding.
Walton
Troy A
TA
Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, CO 80309, USA.
Sousa
Marcelo C
MC
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D013997:Time Factors
D001425:Bacterial Outer Membrane Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D008070:Lipopolysaccharides; D018832:Molecular Chaperones; C072721:Skp protein, E coli; D000255:Adenosine Triphosphate