The NG domain of the prokaryotic signal recognition particle receptor, FtsY, is fully functional when fused to an unrelated integral membrane polypeptide.
Recent studies have revealed that Escherichia coli possesses an essential targeting system for integral membrane proteins, similar to the mammalian signal recognition particle (SRP) machinery. One essential protein in this system is FtsY, a homologue of the alpha-subunit of the mammalian SRP-receptor (SR-alpha). However, E. coli does not possess a close homologue of the integral membrane protein SR-beta, which anchors SR-alpha to the membrane. Moreover, although FtsY can be found as a peripheral membrane protein, the majority is found soluble in the cytoplasm. In this study, we obtained genetic and biochemical evidence that FtsY must be targeted to the membrane for proper function. We demonstrate that the essential membrane targeting activity of FtsY is mediated by a 198-residue-long acidic N-terminal domain. This domain can be functionally replaced by unrelated integral membrane polypeptides, thus avoiding the need for specific FtsY membrane targeting factors. Therefore, the N terminus of FtsY constitutes an independent domain, which is required only for the targeting of the C-terminal NG domain of FtsY to the membrane.
Zelazny
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A
Department of Biochemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
Seluanov
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A
Cooper
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A
Bibi
E
E
D000818:Animals; D001089:Arabinose / Q000378:metabolism; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005816:Genetic Complementation Test; D007700:Kinetics; D008322:Mammals; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis / Q000378:metabolism*; D018000:Receptors, Peptide / Q000096:biosynthesis / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D018271:Signal Recognition Particle / Q000378:metabolism*
D001426:Bacterial Proteins; C087406:FtsY protein, Bacteria; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; D011993:Recombinant Fusion Proteins; D018271:Signal Recognition Particle; C036318:signal peptide receptor; D001089:Arabinose