Characterization of a novel origin recognition complex-like complex: Implications for DNA recognition, cell cycle control, and locus-specific gene amplification

Mohammad Mohammad, Randall D. York, Jonathan Hommel, Geoffrey M. Kapler

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

The origin recognition complex (ORC) plays a central role in eukaryotic DNA replication. Here we describe a unique ORC-like complex in Tetrahymena thermophila, TIF4, which bound in an ATP-dependent manner to sequences required for cell cycle-controlled replication and gene amplification (ribosomal DNA [rDNA] type I elements). TIF4's mode of DNA recognition was distinct from that of other characterized ORCs, as it bound exclusively to single-stranded DNA. In contrast to yeast ORCs, TIF4 DNA binding activity was cell cycle regulated and peaked during S phase, coincident with the redistribution of the Orc2-related subunit, p69, from the cytoplasm to the macronucleus. Origin-binding activity and nuclear p69 immunoreactivity were further regulated during development, where they distinguished replicating from nonreplicating nuclei. Both activities were lost from germ line micronuclei following the programmed arrest of micronuclear replication. Replicating macronuclei stained with Orc2 antibodies throughout development in wild-type cells but failed to do so in the amplification-defective rmm11 mutant. Collectively, these findings indicate that the regulation of TIF4 is intimately tied to the cell cycle and developmentally programmed replication cycles. They further implicate TIF4 in rDNA gene amplification. As type I elements interact with other sequence-specific single-strand breaks (in vitro and in vivo), the dynamic interplay of Orc-like (TIF4) and non-ORC-like proteins with this replication determinant may provide a novel mechanism for regulation.

Original languageEnglish (US)
Pages (from-to)5005-5017
Number of pages13
JournalMolecular and cellular biology
Volume23
Issue number14
DOIs
StatePublished - Jul 2003

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Characterization of a novel origin recognition complex-like complex: Implications for DNA recognition, cell cycle control, and locus-specific gene amplification'. Together they form a unique fingerprint.

Cite this