Role of a small cytoplasmic domain in the establishment of serine chemoreceptor membrane topology.
The Escherichia coli serine chemoreceptor takes on a simple membrane topology with two transmembrane segments separating cytoplasmically disposed N and C termini from a central periplasmic domain. We investigated the role of the small N-terminal cytoplasmic domain in membrane insertion using alkaline phosphatase gene fusions. Mutations eliminating the positive charge of the domain altered insertion dramatically, with reciprocal effects on hybrids with periplasmic and C-terminal cytoplasmic fusion junctions. Efficient export of the normally cytoplasmic C-terminal domain required that, in addition to the N-terminal changes, a short amphiphatic sequence at the beginning of the C-terminal domain be also absent. These findings document the importance of the positive character of the N-terminal domain in chemoreceptor membrane insertion and imply that partially redundant sequence information controls the orientation of the second transmembrane segment.
Kimbrough
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TG
Department of Genetics, University of Washington, Seattle 98195.
Manoil
C
C
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D012694:Serine / Q000378:metabolism
D001426:Bacterial Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; C057635:Tsr protein, Bacteria; D012694:Serine