Different positively charged amino acids have similar effects on the topology of a polytopic transmembrane protein in Escherichia coli.
Integral membrane proteins from a wide variety of sources conform to a "positive-inside rule," with many more positively charged amino acids in their cytoplasmic as compared to extracytoplasmic domains. A growing body of experimental work also points to positively charged residues in regions flanking the apolar transmembrane segments as being the main topological determinants. In this paper, we report a systematic comparison of the effects of positively (Arg, Lys, His) as well as negatively (Asp, Glu) charged residues on the membrane topology of a model Escherichia coli inner membrane protein. Our results show that positive charge is indeed the major factor determining the transmembrane topology, with Arg and Lys being of nearly equal efficiency. His, although normally a very weak topological determinant, can be potentiated by a lowering of the cytoplasmic pH. Asp and Glu affect the topology to similar extents and only when present in very high numbers.
Andersson
H
H
Department of Molecular Biology, Karolinska Institute Center for Biotechnology, NOVUM, Huddinge, Sweden.
Bakker
E
E
von Heijne
G
G
D000595:Amino Acid Sequence; D001120:Arginine; D001224:Aspartic Acid; D002462:Cell Membrane / Q000378:metabolism; D010450:Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D005971:Glutamates; D018698:Glutamic Acid; D008239:Lysine; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008961:Models, Structural; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010449:Peptide Mapping; D011487:Protein Conformation; D012697:Serine Endopeptidases
D005971:Glutamates; D008565:Membrane Proteins; D001224:Aspartic Acid; D018698:Glutamic Acid; D001120:Arginine; D010450:Endopeptidases; D012697:Serine Endopeptidases; C026515:type I signal peptidase; D008239:Lysine