title: Interactions of (Ala*Ala*Lys*Pro)n and (Lys*Lys*Ser*Pro)n with DNA. Proposed coiled-coil structure of AlgR3 and AlgP from Pseudomonas aeruginosa.
abstract: The proteins, AlgR3 and AlgP, are involved in the regulation of alginate synthesis in Pseudomonas. They contain multiple repeats of Ala*Ala*Lys*Pro as do several other proteins that resemble histones. The interactions of synthesis oligopeptides composed of repeated Ala*Ala*Lys*Pro or Lys*Lys*Ser*Pro units with DNA were studied by fluorescence of the Fmoc (9-fluorenylmethyloxycarbonyl) group attached to the N-termini of the peptides. DNA quenching of the Fmoc fluorescence of the peptides was used to estimate the apparent association constants for the interaction of Fmoc(AAKP)nOH (n = 2, 4, 8, 18, 32) and of Fmoc (KKSP)nOH (n = 2, 4, 8, 16, 20, 32) with DNA. The Fmoc(AAKP)nOH peptides bind to DNA only at low ionic strength; the Fmoc(KKSP)n OH peptides interact with DNA at both low (0.05 M KCl) and high (0.2 M KCl) salt. At low ionic strength an increase in the number of the repeat units causes an increase in the apparent association constant up to approximately 2 x 10(6) M-1 for both types of peptides at N congruent to 24. The insertion of an AAKTA unit into the middle of the Fmoc(AAKP)8OH peptide increases its affinity to DNA. We propose a model of (AAKP)n and of its interaction with DNA. The repeat unit consists of a single turn of alpha-helix followed by a bend necessitated by Pro. The resultant coiled-coil forms a right-handed superhelix with 10 AAKPs per repeat distance of approximately 33 A.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region.
authors.forename: V N
authors.initials: VN
authors.lastname: Medvedkin
authors.forename: E A
authors.initials: EA
authors.lastname: Permyakov
authors.forename: L V
authors.initials: LV
authors.lastname: Klimenko
authors.forename: Y V
authors.initials: YV
authors.lastname: Mitin
authors.forename: N
authors.initials: N
authors.lastname: Matsushima
authors.forename: S
authors.initials: S
authors.lastname: Nakayama
authors.forename: R H
authors.initials: RH
authors.lastname: Kretsinger
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011550:Pseudomonas aeruginosa / Q000737:chemistry / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D013050:Spectrometry, Fluorescence; D014157:Transcription Factors
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors; C072452:algP protein, Pseudomonas aeruginosa; D004247:DNA