title: Functional analysis of subcellular localization and protein-protein interaction sequences in the essential DNA ligase I protein of fission yeast.
abstract: DNA ligase I (Lig I) has key roles in chromosomal DNA replication and repair in the eukaryotic cell nucleus. In the budding yeast Saccharomyces cerevisiae the Lig I enzyme Cdc9p is also required for mitochondrial DNA replication and repair. In this report, dual nuclear-mitochondrial localization is demonstrated to be a property of the essential Lig I enzyme Cdc17 from the distantly related fission yeast Schizosaccharomyces pombe. Expression of nuclear and mitochondrial forms of Cdc17 from separate genes shows that, whereas expression of either protein alone is insufficient to restore viability to cells lacking endogenous Cdc17, co-expression restores full viability. In the nucleus, Lig I interacts with the sliding clamp proliferating cell nuclear antigen (PCNA) via a conserved PCNA interacting sequence motif known as a PIP box. Deletion of the PIP motif from the N-terminus of the nuclear form of Cdc17 fails to abolish Cdc17 function, indicating that PCNA binding by Cdc17 is not an absolute requirement for completion of S-phase.
authors.affiliation: Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, King's Buildings, Mayfield Road, Edinburgh EH9 3JR, UK.
authors.forename: Ina V
authors.initials: IV
authors.lastname: Martin
authors.forename: Stuart A
authors.initials: SA
authors.lastname: MacNeill
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000201:enzymology; D003001:Cloning, Molecular; D018387:Codon, Initiator / Q000235:genetics; D017124:Conserved Sequence; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D008928:Mitochondria / Q000201:enzymology; D008969:Molecular Sequence Data; D009154:Mutation; D019913:Nuclear Localization Signals; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012568:Schizosaccharomyces / Q000166:cytology* / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
chemical_list: D018387:Codon, Initiator; D019913:Nuclear Localization Signals; D018809:Proliferating Cell Nuclear Antigen; D029702:Schizosaccharomyces pombe Proteins; D011088:DNA Ligases; C483777:Cdc17 protein, S pombe; D000072481:DNA Ligase ATP