title: A novel member of the bacterial-archaeal regulator family is a nonspecific dna-binding protein and induces positive supercoiling.
abstract: In hyperthermophilic Archaea genomic DNA is from relaxed to positively supercoiled in vivo because of the action of the enzyme reverse gyrase, and this peculiarity is believed to be related to stabilization of DNA against denaturation. We report the identification and characterization of Smj12, a novel protein of Sulfolobus solfataricus, which is homologous to members of the so-called Bacterial-Archaeal family of regulators, found in multiple copies in Eubacteria and Archaea. Whereas other members of the family are sequence-specific DNA- binding proteins and have been implicated in transcriptional regulation, Smj12 is a nonspecific DNA-binding protein that stabilizes the double helix and induces positive supercoiling. Smj12 is not abundant, suggesting that it is not a general architectural protein, but rather has a specialized function and/or localization. Smj12 is the first protein with the described features identified in Archaea and might participate in control of superhelicity during DNA transactions.
authors.affiliation: Institute of Protein Biochemistry and Enzymology, Consiglio Nazionale delle Ricerche, Via Marconi 10, 80125 Naples, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Napoli
authors.forename: M
authors.initials: M
authors.lastname: Kvaratskelia
authors.forename: M F
authors.initials: MF
authors.lastname: White
authors.forename: M
authors.initials: M
authors.lastname: Rossi
authors.forename: M
authors.initials: M
authors.lastname: Ciaramella
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D016944:Sulfolobus
chemical_list: D019843:Archaeal Proteins; D004268:DNA-Binding Proteins