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We have dissected specialized assemblies on the Saccharomyces cerevisiae genome that help define and preserve the boundaries that separate silent and active chromatin. These assemblies contain characteristic stretches of DNA that flank particular regions of silent chromatin, as well as five distinctively modified histones and a set of protein complexes. The… (More)
Clamp loaders are required to load the ring-shaped clamps that tether replicative DNA polymerases onto DNA. Recently solved crystal structures, along with a series of biochemical studies, have provided a detailed understanding of the clamp loading reaction. In particular, studies of the Escherichia coli clamp loader--an AAA+ machine--have provided insights… (More)
Helicases are transferred to replication origins by helicase loading factors. The Escherichia coli DnaC and eukaryotic Cdc6/18 helicase loaders contain ATP sites and are both members of the AAA+ family. One might expect that ATP is required for helicase loading; however, this study on DnaC illustrates that ATP is not actually needed for DnaC to load… (More)
This study outlines the events downstream of origin unwinding by DnaA, leading to assembly of two replication forks at the E. coli origin, oriC. We show that two hexamers of DnaB assemble onto the opposing strands of the resulting bubble, expanding it further, yet helicase action is not required. Primase cannot act until the helicases move 65 nucleotides or… (More)
ParA is an essential P1 plasmid partition protein. It represses transcription of the par genes (parA and parB) and is also required for a second, as yet undefined step in partition. ParA is a ParB-stimulated ATPase that binds to a specific DNA site in the par promoter region. ATP binding and hydrolysis by ParA affect ParA activities in vitro. ATP and ADP… (More)
Tom1p is a 3268-amino acid protein with extensive homology to the hect-domain class of E3 ubiquitin ligases. Disruption of the TOMI gene results in temperature sensitivity for growth. Genes encoding the peptidyl proline isomerases Fpr3p and Fpr4p, when present on multicopy plasmids, will suppress this temperature-sensitive growth phenotype. FPR3 can also… (More)
The pre-sensor 1 (PS1) hairpin is found in ring-shaped helicases of the AAA+ family (ATPases associated with a variety of cellular activities) of proteins and is implicated in DNA translocation during DNA unwinding of archaeal mini-chromosome maintenance (MCM) and superfamily 3 viral replicative helicases. To determine whether the PS1 hairpin is required… (More)
Advances in recent years have led to exciting new ideas about the initiation, regulation and coordination of DNA replication. Structural studies have yielded fascinating glimpses of replisome action. In addition, the involvement of replication proteins in other cellular processes has blurred the lines between replication, repair and recombination.
Macrophages are involved in many aspects of development, host defense, pathology, and homeostasis. Their normal differentiation, proliferation, and survival are controlled by CSF-1 via the activation of the CSF1R. A recently discovered cytokine, IL-34, was shown to bind the same receptor in humans. Chicken is a widely used model organism in developmental… (More)
Helicase loaders transfer the ring-shaped replicative helicases onto DNA. They assort into two classes: ring breakers, which place stabile hexameric rings on DNA via transient gaps at subunit interfaces; and helicase makers, which assemble hexameric rings around DNA from monomeric helicase units.