title: The functional importance of structural differences between the mannitol-specific IIAmannitol and the regulatory IIAnitrogen.
abstract: The three-dimensional structures of the IIA domain of the mannitol-specific phosphoenol-pyruvate dependent phosphotransferase system (PTS) of Escherichia coli and the regulatory IIAntr enzyme have been compared. The enzymes are 20% identical in sequence and contain the sequence motif specific for IIA proteins belonging to the mannitol-fructose family of the PTS. The fold of the enzymes is nearly identical, which confirms their evolution from a common ancestor. Moreover, the phosphorylation site of IIAmtl (His65) and one of the observed conformations of the active site Arg49 are extremely similar to their equivalents (His73 and Arg57) in IIAntr. In contrast, His120, the equivalent of the second active site His111 of IIAmtl, is not located in the active site of IIAntr but points into the solvent on the other side of the molecule. The different position of His120 makes it unlikely that this residue assists in phosphoryl transfer in the regulatory IIA(ntr)s. As His120 is conserved in all IIAntr enzymes, it could have an essential role in the recognition of the target protein of IIAntr.
authors.affiliation: Laboratory of Biophysical Chemistry and BIOSON Research Institute, University of Groningen, The Netherlands.
authors.forename: R L
authors.initials: RL
authors.lastname: van Montfort
authors.forename: B W
authors.initials: BW
authors.lastname: Dijkstra
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry*; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins; D019143:Evolution, Molecular; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D051922:PII Nitrogen Regulatory Proteins; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000737:chemistry*; D010766:Phosphorylation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D012808:Sigma Factor / Q000235:genetics; D015534:Trans-Activators; D014157:Transcription Factors
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D009004:Monosaccharide Transport Proteins; D051922:PII Nitrogen Regulatory Proteins; D012808:Sigma Factor; D015534:Trans-Activators; D014157:Transcription Factors; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C022358:mannitol PTS permease, E coli