title: The three-dimensional structure of the nitrogen regulatory protein IIANtr from Escherichia coli.
abstract: The bacterial rpoN operon codes for sigma 54, which is the key sigma factor that, under nitrogen starvation conditions, activates the transcription of genes needed to assimilate ammonia and glutamate. The rpoN operon contains several other open reading frames that are cotranscribed with sigma 54. The product of one of these, the 17.9 kDa protein IIANtr, is homologous to IIA proteins of the phosphoenolpyruvate:sugar phosphotransferase (PTS) system. IIANtr influences the transcription of sigma 54-dependent genes through an unknown mechanism and may thereby provide a regulatory link between carbon and nitrogen metabolism. Here we describe the 2.35 A X-ray structure of Escherichia coli IIANtr. It is the first structure of a IIA enzyme from the fructose-mannitol family of the PTS. The enzyme displays a novel fold characterized by a central mixed parallel/anti-parallel beta-sheet surrounded by six alpha-helices. The active site His73 is situated in a shallow depression on the protein surface.
authors.affiliation: Laboratory of Biophysical Chemistry, University of Groningen, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Bordo
authors.forename: R L
authors.initials: RL
authors.lastname: van Monfort
authors.forename: T
authors.initials: T
authors.lastname: Pijning
authors.forename: K H
authors.initials: KH
authors.lastname: Kalk
authors.forename: J
authors.initials: J
authors.lastname: Reizer
authors.forename: M H
authors.initials: MH
authors.lastname: Saier
authors.forename: B W
authors.initials: BW
authors.lastname: Dijkstra
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry*; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D051922:PII Nitrogen Regulatory Proteins; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000737:chemistry; D011487:Protein Conformation; D051877:RNA Polymerase Sigma 54; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012808:Sigma Factor / Q000737:chemistry; D015534:Trans-Activators; D014157:Transcription Factors
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D051922:PII Nitrogen Regulatory Proteins; D012808:Sigma Factor; D015534:Trans-Activators; D014157:Transcription Factors; C497751:rpoN protein, E coli; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54