Anionic phospholipids are involved in membrane association of FtsY and stimulate its GTPase activity.
FtsY, the Escherichia coli homologue of the eukaryotic signal recognition particle (SRP) receptor alpha-subunit, is located in both the cytoplasm and inner membrane. It has been proposed that FtsY has a direct targeting function, but the mechanism of its association with the membrane is unclear. FtsY is composed of two hydrophilic domains: a highly charged N-terminal domain (the A-domain) and a C-terminal GTP-binding domain (the NG-domain). FtsY does not contain any hydrophobic sequence that might explain its affinity for the inner membrane, and a membrane-anchoring protein has not been detected. In this study, we provide evidence that FtsY interacts directly with E.coli phospholipids, with a preference for anionic phospholipids. The interaction involves at least two lipid-binding sites, one of which is present in the NG-domain. Lipid association induced a conformational change in FtsY and greatly enhanced its GTPase activity. We propose that lipid binding of FtsY is important for the regulation of SRP-mediated protein targeting.
de Leeuw
E
E
Department of Microbiology, Institute of Molecular Biological Sciences, Biocentrum Amsterdam, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands.
te Kaat
K
K
Moser
C
C
Menestrina
G
G
Demel
R
R
de Kruijff
B
B
Oudega
B
B
Luirink
J
J
Sinning
I
I
D000838:Anions; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000737:chemistry* / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D008081:Liposomes; D010743:Phospholipids / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000378:metabolism*; D018271:Signal Recognition Particle / Q000737:chemistry / Q000378:metabolism; D055672:Static Electricity
D000838:Anions; D001426:Bacterial Proteins; C087406:FtsY protein, Bacteria; D008081:Liposomes; D010743:Phospholipids; D018160:Receptors, Cytoplasmic and Nuclear; D018271:Signal Recognition Particle; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases