title: A novel type of zinc finger DNA binding domain in the Agrobacterium tumefaciens transcriptional regulator Ros.
abstract: Transcriptional factors bearing a Cys(2)His(2) zinc finger were thought to be confined to eukaryotes, but recent studies have suggested their presence also in prokaryotes. In this paper, we report the first complete functional characterization of the DNA binding domain present in the putative Cys(2)His(2) zinc finger-containing prokaryotic transcriptional regulator Ros from Agrobacterium tumefaciens. We demonstrate that in the single zinc binding motif present in the Ros protein the metal ion is coordinated by two cysteines (Cys79 and Cys82) and two histidines (His92 and His97), separated by a shorter spacer with respect to the eukaryotic classical Cys(2)His(2) domains. The Cys(2)His(2) zinc finger motif is essential for Ros DNA binding and is part of a larger DNA binding domain which includes four basic regions located on either side of the finger, one at the N-terminus and three at the C-terminus. The one described here is a novel type of DNA binding domain containing a noncanonical Cys(2)His(2) zinc finger motif which, by sequence alignment, seems to be conserved in all the bacterial putative zinc finger proteins identified so far. Interestingly, basic amino acids have been shown to be important in stabilizing the DNA binding of eukaryotic single Cys(2)His(2) zinc finger domains, confirming that the modality of DNA binding using a single zinc finger motif flanked by basic residues is widespread throughout the living kingdom from eukaryotic, both animal and plant, to prokaryotic, even if in each kingdom it presents its peculiarity.
authors.affiliation: Dipartimento di Scienze Ambientali, Seconda Università degli Studi di Napoli, via Vivaldi 43, 81100 Caserta, Italy.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Esposito
authors.forename: Ilaria
authors.initials: I
authors.lastname: Baglivo
authors.forename: Gaetano
authors.initials: G
authors.lastname: Malgieri
authors.forename: Luigi
authors.initials: L
authors.lastname: Russo
authors.forename: Laura
authors.initials: L
authors.lastname: Zaccaro
authors.forename: Luca D
authors.initials: LD
authors.lastname: D'Andrea
authors.forename: Marco
authors.initials: M
authors.lastname: Mammucari
authors.forename: Benedetto
authors.initials: B
authors.lastname: Di Blasio
authors.forename: Carla
authors.initials: C
authors.lastname: Isernia
authors.forename: Roberto
authors.initials: R
authors.lastname: Fattorusso
authors.forename: Paolo V
authors.initials: PV
authors.lastname: Pedone
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010944:Plants / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D015032:Zinc / Q000378:metabolism; D016335:Zinc Fingers / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D015032:Zinc