title: The T4 phage DNA mimic protein Arn inhibits the DNA binding activity of the bacterial histone-like protein H-NS.
abstract: The T4 phage protein Arn (Anti restriction nuclease) was identified as an inhibitor of the restriction enzyme McrBC. However, until now its molecular mechanism remained unclear. In the present study we used structural approaches to investigate biological properties of Arn. A structural analysis of Arn revealed that its shape and negative charge distribution are similar to dsDNA, suggesting that this protein could act as a DNA mimic. In a subsequent proteomic analysis, we found that the bacterial histone-like protein H-NS interacts with Arn, implying a new function. An electrophoretic mobility shift assay showed that Arn prevents H-NS from binding to the Escherichia coli hns and T4 p8.1 promoters. In vitro gene expression and electron microscopy analyses also indicated that Arn counteracts the gene-silencing effect of H-NS on a reporter gene. Because McrBC and H-NS both participate in the host defense system, our findings suggest that T4 Arn might knock down these mechanisms using its DNA mimicking properties.
authors.affiliation: Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan,; Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Chun-Han
authors.initials: CH
authors.lastname: Ho
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan; Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan.
authors.forename: Hao-Ching
authors.initials: HC
authors.lastname: Wang
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan; Core Facilities for Protein Structural Analysis, and Academia Sinica, Taipei 115, Taiwan.
authors.forename: Tzu-Ping
authors.initials: TP
authors.lastname: Ko
authors.affiliation: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan, and.
authors.forename: Yuan-Chih
authors.initials: YC
authors.lastname: Chang
authors.affiliation: Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan,; Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan; Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan; Core Facilities for Protein Structural Analysis, and Academia Sinica, Taipei 115, Taiwan. Electronic address: ahjwang@gate.sinica.edu.tw.
authors.forename: Andrew H-J
authors.initials: AH
authors.lastname: Wang
mesh_terms: D017122:Bacteriophage T4 / Q000235:genetics / Q000378:metabolism*; D004262:DNA Restriction Enzymes / Q000235:genetics / Q000378:metabolism; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D015967:Gene Expression Regulation, Viral; D020868:Gene Silencing; D011485:Protein Binding; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004279:DNA, Viral; D029968:Escherichia coli Proteins; C529458:FimG protein, E coli; D014764:Viral Proteins; C069326:mcrC protein, E coli; D036781:Fimbriae Proteins; D004262:DNA Restriction Enzymes; C059678:mcrB protein, E coli
keywords: Crystal Structure; DNA Mimic Protein; DNA-binding Protein; Molecular Mimicry; Protein Structure; Protein-DNA Interaction; Protein-Protein Interaction