title: The acidic C-terminus of vaccinia virus I3 single-strand binding protein promotes proper assembly of DNA-protein complexes.
abstract: The vaccinia virus I3L gene encodes a single-stranded DNA binding protein (SSB) that is essential for virus DNA replication and is conserved in all Chordopoxviruses. The I3 protein contains a negatively charged C-terminal tail that is a common feature of SSBs. Such acidic tails are critical for SSB-dependent replication, recombination and repair. We cloned and purified variants of the I3 protein, along with a homolog from molluscum contagiosum virus, and tested how the acidic tail affected DNA-protein interactions. Deleting the C terminus of I3 enhanced the affinity for single-stranded DNA cellulose and gel shift analyses showed that it also altered the migration of I3-DNA complexes in agarose gels. Microinjecting an antibody against I3 into vaccinia-infected cells also selectively inhibited virus replication. We suggest that this domain promotes cooperative binding of I3 to DNA in a way that would maintain an open DNA configuration around a replication site.
authors.affiliation: Department of Medical Microbiology & Immunology, Li Ka-Shing Institute for Virology, 6020 Katz Group Centre, University of Alberta, Edmonton, AB, Canada T6G 2E1.
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Harrison
authors.affiliation: Department of Medical Microbiology & Immunology, Li Ka-Shing Institute for Virology, 6020 Katz Group Centre, University of Alberta, Edmonton, AB, Canada T6G 2E1.
authors.forename: Megan A
authors.initials: MA
authors.lastname: Desaulniers
authors.affiliation: Department of Medical Microbiology & Immunology, Li Ka-Shing Institute for Virology, 6020 Katz Group Centre, University of Alberta, Edmonton, AB, Canada T6G 2E1.
authors.forename: Ryan S
authors.initials: RS
authors.lastname: Noyce
authors.affiliation: Department of Medical Microbiology & Immunology, Li Ka-Shing Institute for Virology, 6020 Katz Group Centre, University of Alberta, Edmonton, AB, Canada T6G 2E1. Electronic address: devans@ualberta.ca.
authors.forename: David H
authors.initials: DH
authors.lastname: Evans
mesh_terms: D020816:Amino Acid Motifs; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral; D006801:Humans; D014615:Vaccinia / Q000821:virology*; D014616:Vaccinia virus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D004279:DNA, Viral; D004268:DNA-Binding Proteins; C111416:I3 protein, Vaccinia virus; D014764:Viral Proteins
keywords: DNA replication; I3L; Molluscum contagiosum virus; Single-strand DNA binding protein; Vaccinia virus