Membrane pore formation by pentraxin proteins from Limulus, the American horseshoe crab.
The pentraxins are a family of highly conserved plasma proteins of metazoans known to function in immune defence. The canonical members, C-reactive protein and serum amyloid P component, have been identified in arthropods and humans. Mammalian pentraxins are known to bind lipid bilayers, and a pentraxin representative from the American horseshoe crab, Limulus polyphemus, binds and permeabilizes mammalian erythrocytes. Both activities are Ca(2+)-dependent. Utilizing model liposomes and planar lipid bilayers, in the present study we have investigated the membrane-active properties of the three pentraxin representatives from Limulus and show that all of the Limulus pentraxins permeabilize lipid bilayers. Mechanistically, Limulus C-reactive protein forms transmembrane pores in asymmetric planar lipid bilayers that mimic the outer membrane of Gram-negative bacteria and exhibits a Ca(2+)-independent form of membrane binding that may be sufficient for pore formation.
Harrington
John M
JM
Department of Molecular and Cellular Biology, University of California, One Shields Avenue, Davis, CA 95616, USA.
Chou
Hui-Ting
HT
Gutsmann
Thomas
T
Gelhaus
Christoph
C
Stahlberg
Henning
H
Leippe
Matthias
M
Armstrong
Peter B
PB
D000818:Animals; D002097:C-Reactive Protein / Q000737:chemistry* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005452:Fluoresceins / Q000737:chemistry; D006737:Horseshoe Crabs; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism; D010713:Phosphatidylcholines / Q000737:chemistry; D000099153:Pentraxins
D002097:C-Reactive Protein; D002118:Calcium; D005452:Fluoresceins; D008051:Lipid Bilayers; D008055:Lipids; D008081:Liposomes; D009419:Nerve Tissue Proteins; D010713:Phosphatidylcholines; D000099153:Pentraxins; C024990:asolectin; C007740:fluorexon