title: An experimentally tested scenario for the structural evolution of eukaryotic Cys2His2 zinc fingers from eubacterial ros homologs.
abstract: The exact evolutionary origin of the zinc finger (ZF) domain is unknown, as it is still not clear from which organisms it was first derived. However, the unique features of the ZF domains have made it very easy for evolution to tinker with them in a number of different manners, including their combination, variation of their number by unequal crossing-over or tandem duplication and tuning of their affinity for specific DNA sequence motifs through point substitutions. Classical Cys2His2 ZF domains as structurally autonomous motifs arranged in multiple copies are known only in eukaryotes. Nonetheless, a single prokaryotic Cys2His2 ZF domain has been identified in the transcriptional regulator Ros from Agrobacterium tumefaciens and recently characterized. The present work focuses on the evolution of the classical ZF domains with the goal of trying to determine whether eukaryotic ZFs have evolved from the prokaryotic Ros-like proteins. Our results, based on computational and experimental data, indicate that a single insertion of three amino acids in the short loop that separates the β-sheet from the α-helix of the Ros protein is sufficient to induce a structural transition from a Ros like to an eukaryotic-ZF like structure. This observation provides evidence for a structurally plausible and parsimonious scenario of fold evolution, giving a structural basis to the hypothesis of a horizontal gene transfer (HGT) from bacteria to eukaryotes.
authors.affiliation: Dipartimento di Scienze Ambientali, Biologiche e Farmaceutiche, Seconda Università di Napoli , Via Vivaldi 43, 81100 Caserta, Italy.
authors.forename: Fortuna
authors.initials: F
authors.lastname: Netti
authors.forename: Gaetano
authors.initials: G
authors.lastname: Malgieri
authors.forename: Sabrina
authors.initials: S
authors.lastname: Esposito
authors.forename: Maddalena
authors.initials: M
authors.lastname: Palmieri
authors.forename: Ilaria
authors.initials: I
authors.lastname: Baglivo
authors.forename: Carla
authors.initials: C
authors.lastname: Isernia
authors.forename: James G
authors.initials: JG
authors.lastname: Omichinski
authors.forename: Paolo V
authors.initials: PV
authors.lastname: Pedone
authors.forename: Nicolas
authors.initials: N
authors.lastname: Lartillot
authors.forename: Roberto
authors.initials: R
authors.lastname: Fattorusso
mesh_terms: D016960:Agrobacterium tumefaciens / Q000737:chemistry* / Q000235:genetics; D000595:Amino Acid Sequence; D001419:Bacteria / Q000737:chemistry / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D001665:Binding Sites; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D016335:Zinc Fingers
chemical_list: D001426:Bacterial Proteins
keywords: evolution; nuclear magnetic resonance; phylogenetics analysis; zinc finger domain