Elucidation of the function of lipoprotein-sorting signals that determine membrane localization
- Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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Edited by M. J. Osborn, University of Connecticut Health Center, Farmington, CT, and approved April 11, 2002 (received for review February 12, 2002)
Abstract
Escherichia coli lipoproteins are anchored to the inner or outer membrane depending on the residue at position 2. Aspartate at this position makes lipoproteins specific to the inner membrane, whereas other residues cause the release of lipoproteins from the inner membrane in a manner dependent on both ATP binding cassette (ABC) transporter LolCDE and molecular chaperone LolA, followed by LolB-dependent localization in the outer membrane. The function of lipoprotein-sorting signals was examined in proteoliposomes reconstituted from LolCDE and lipoproteins. The release of outer membrane-specific lipoproteins was inhibited on reconstitution with other outer membrane-specific, but not inner membrane-specific, lipoproteins. Outer membrane-specific lipoproteins stimulated ATP hydrolysis by LolCDE whereas inner membrane-specific ones did not. LolA was not required for the stimulation of ATP hydrolysis. These results revealed a previously undocumented function of aspartate at position 2, i.e., lipoproteins having this signal avoid being recognized by LolCDE, thereby remaining in the inner membrane.
Footnotes
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↵ * To whom reprint requests should be addressed. E-mail: htokuda{at}imcbns.iam.utokyo.ac.jp.
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This paper was submitted directly (Track II) to the PNAS office.
- Abbreviation:
- ABC,
- ATP binding cassette
- Copyright © 2002, The National Academy of Sciences
