title: Sequence features of substrates required for cleavage by GlpG, an Escherichia coli rhomboid protease.
abstract: Rhomboids are a family of serine proteases belonging to intramembrane cleaving proteases, which are supposed to catalyse proteolysis of a substrate protein within the membrane. It remains unclear whether substrates of the rhomboid proteases have a common sequence feature that allows specific cleavage by rhomboids. We showed previously that GlpG, the Escherichia coli rhomboid, can cleave a type I model membrane protein Bla-LY2-MBP having the second transmembrane region of lactose permease (LY2) at the extramembrane region in vivo and in vitro, and that determinants for proteolysis reside within the LY2 sequence. Here we characterized sequence features in LY2 that allow efficient cleavage by GlpG and identified two elements, a hydrophilic region encompassing the cleavage site and helix-destabilizing residues in the downstream hydrophobic region. Importance of the positioning of helix-destabilizers relative to the cleavage site was suggested. These two elements appear to co-operatively promote proteolysis of substrates by GlpG. Finally, random mutagenesis of the cleavage site residues in combination with in vivo screening revealed that GlpG prefers residues with a small side chain and a negative charge at the P1 and P1' sites respectively.
authors.affiliation: Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan. yakiyama@virus.kyoto-u.ac.jp
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Akiyama
authors.forename: Saki
authors.initials: S
authors.lastname: Maegawa
mesh_terms: D000595:Amino Acid Sequence; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010450:Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000737:chemistry / Q000378:metabolism; D016296:Mutagenesis; D011487:Protein Conformation; D013379:Substrate Specificity; D027981:Symporters / Q000737:chemistry / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C102898:GlpG protein, E coli; C050221:LacY protein, E coli; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D027981:Symporters; D010450:Endopeptidases