Topography of the surface of the Escherichia coli phosphotransferase system protein enzyme IIAglc that interacts with lactose permease.
The unphosphorylated form of enzyme IIAglc of the Escherichia coli phosphoenolpyruvate:sugar phosphotransferase system inhibits transport catalyzed by lactose permease. We (Seok et al. (1997) Proc. Natl. Acad. Sci. U.S.A. 94, 13515-13519) previously characterized the area on the cytoplasmic face of lactose permease that interacts with enzyme IIAglc, using radioactive enzyme IIAglc. Subsequent studies (Sondej et al. (1999) Proc. Natl. Acad. Sci. U.S.A. 96, 3525-3530) suggested consensus binding sequences on proteins that interact with enzyme IIAglc. The present study characterizes a region on the surface of enzyme IIAglc that interfaces with lactose permease. Acetylation of lysine residues by sulfosuccinimidyl acetate treatment of enzyme IIAglc, but not lactose permease, reduced the degree of interaction between the two proteins. To localize the lysine residue(s) on enzyme IIAglc that is(are) involved in the regulatory interaction, selected lysine residues were mutagenized. Conversion of nine separate lysines to glutamic acid resulted in proteins that were still capable of phosphoryl acceptance from HPr. Except for Lys69, all the modified proteins were as effective as the wild-type enzyme IIAglc in a test for binding to lactose permease. The Lys69 mutant was also defective in phosphoryl transfer to glucose permease. To derive further information concerning the contact surface, additional selected residues in the vicinity of Lys69 were mutagenized and tested for binding to lactose permease. On the basis of these studies, a model for the region of the surface of enzyme IIAglc that interacts with lactose permease is proposed.
Sondej
M
M
Laboratory of Biochemical Genetics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Seok
Y J
YJ
Badawi
P
P
Koo
B M
BM
Nam
T W
TW
Peterkofsky
A
A
D000085:Acetates / Q000494:pharmacology; D000107:Acetylation; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029968:Escherichia coli Proteins; D008239:Lysine / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D016297:Mutagenesis, Site-Directed; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D013388:Succinimides / Q000494:pharmacology; D027981:Symporters
D000085:Acetates; D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D013388:Succinimides; D027981:Symporters; C032242:crr protein, E coli; C088219:sulfosuccinimidyl acetate; C021499:lactose permease; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D008239:Lysine