Genetic analyses of Schizosaccharomyces pombe dna2(+) reveal that dna2 plays an essential role in Okazaki fragment metabolism.
Genetics
; 155(3): 1055-67, 2000 Jul.
Article
em En
| MEDLINE
| ID: mdl-10880469
ABSTRACT
In this report, we investigated the phenotypes caused by temperature-sensitive (ts) mutant alleles of dna2(+) of Schizosaccharomyces pombe, a homologue of DNA2 of budding yeast, in an attempt to further define its function in vivo with respect to lagging-strand synthesis during the S-phase of the cell cycle. At the restrictive temperature, dna2 (ts) cells arrested at late S-phase but were unaffected in bulk DNA synthesis. Moreover, they exhibited aberrant mitosis when combined with checkpoint mutations, in keeping with a role for Dna2 in Okazaki fragment maturation. Similarly, spores in which dna2(+) was disrupted duplicated their DNA content during germination and also arrested at late S-phase. Inactivation of dna2(+) led to chromosome fragmentation strikingly similar to that seen when cdc17(+), the DNA ligase I gene, is inactivated. The temperature-dependent lethality of dna2 (ts) mutants was suppressed by overexpression of genes encoding subunits of polymerase delta (cdc1(+) and cdc27(+)), DNA ligase I (cdc17(+)), and Fen-1 (rad2(+)). Each of these gene products plays a role in the elongation or maturation of Okazaki fragments. Moreover, they all interacted with S. pombe Dna2 in a yeast two-hybrid assay, albeit to different extents. On the basis of these results, we conclude that dna2(+) plays a direct role in the Okazaki fragment elongation and maturation. We propose that dna2(+) acts as a central protein to form a complex with other proteins required to coordinate the multienzyme process for Okazaki fragment elongation and maturation.
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MEDLINE
Assunto principal:
Schizosaccharomyces
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DNA
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Adenosina Trifosfatases
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DNA Helicases
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Fatores de Troca do Nucleotídeo Guanina
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Proteínas de Saccharomyces cerevisiae
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Proteínas de Ligação a DNA
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Endodesoxirribonucleases
Idioma:
En
Ano de publicação:
2000
Tipo de documento:
Article