scholarly journals Replication Factor C3 of Schizosaccharomyces pombe, a Small Subunit of Replication Factor C Complex, Plays a Role in Both Replication and Damage Checkpoints

1999 ◽  
Vol 10 (12) ◽  
pp. 3991-4003 ◽  
Author(s):  
Midori Shimada ◽  
Daisuke Okuzaki ◽  
Seiji Tanaka ◽  
Takahiro Tougan ◽  
Katsuyuki K. Tamai ◽  
...  

We report here the isolation and functional analysis of therfc3 + gene of Schizosaccharomyces pombe, which encodes the third subunit of replication factor C (RFC3). Because the rfc3 + gene was essential for growth, we isolated temperature-sensitive mutants. One of the mutants, rfc3-1, showed aberrant mitosis with fragmented or unevenly separated chromosomes at the restrictive temperature. In this mutant protein, arginine 216 was replaced by tryptophan. Pulsed-field gel electrophoresis suggested that rfc3-1cells had defects in DNA replication. rfc3-1 cells were sensitive to hydroxyurea, methanesulfonate (MMS), and gamma and UV irradiation even at the permissive temperature, and the viabilities after these treatments were decreased. Using cells synchronized in early G2 by centrifugal elutriation, we found that the replication checkpoint triggered by hydroxyurea and the DNA damage checkpoint caused by MMS and gamma irradiation were impaired inrfc3-1 cells. Association of Rfc3 and Rad17 in vivo and a significant reduction of the phosphorylated form of Chk1 inrfc3-1 cells after treatments with MMS and gamma or UV irradiation suggested that the checkpoint signal emitted by Rfc3 is linked to the downstream checkpoint machinery via Rad17 and Chk1. From these results, we conclude that rfc3 + is required not only for DNA replication but also for replication and damage checkpoint controls, probably functioning as a checkpoint sensor.

Genetics ◽  
1996 ◽  
Vol 142 (1) ◽  
pp. 65-78 ◽  
Author(s):  
Michael A McAlear ◽  
K Michelle Tuffo ◽  
Connie Holm

We used genetic and biochemical techniques to characterize the phenotypes associated with mutations affecting the large subunit of replication factor C (Cdc44p or Rfc1p) in Saccharomyces cerevisiae. We demonstrate that Cdc44p is required for both DNA replication and DNA repair in vivo. Cold-sensitive cdc44 mutants experience a delay in traversing S phase at the restrictive temperature following alpha factor arrest; although mutant cells eventually accumulate with a G2/M DNA content, they undergo a cell cycle arrest and initiate neither mitosis nor a new round of DNA synthesis. cdc44 mutants also exhibit an elevated level of spontaneous mutation, and they are sensitive both to the DNA damaging agent methylmethane sulfonate and to exposure to UV radiation. After exposure to UV radiation, cdc44 mutants at the restrictive temperature contain higher levels of single-stranded DNA breaks than do wild-type cells. This observation is consistent with the hypothesis that Cdc44p is involved in repairing gaps in the DNA after the excision of damaged bases. Thus, Cdc44p plays an important role in both DNA replication and DNA repair in vivo.


2003 ◽  
Vol 23 (8) ◽  
pp. 2999-3007 ◽  
Author(s):  
Margaret A. Kenna ◽  
Robert V. Skibbens

ABSTRACT CTF7/ECO1 is an essential yeast gene required for the establishment of sister chromatid cohesion. The findings that CTF7/ECO1, POL30 (PCNA), and CHL12/CTF18 (a replication factor C [RFC] homolog) genetically interact provided the first evidence that the processes of cohesion establishment and DNA replication are intimately coupled—a link now confirmed by other studies. To date, however, it is unknown how Ctf7p/Eco1p function is coupled to DNA replication or whether Ctf7p/Eco1p physically associates with any components of the DNA replication machinery. Here, we report that Ctf7p/Eco1p associates with proteins that perform partially redundant functions in DNA replication. Chl12p/Ctf18p combines with Rfc2p to Rfc5p to form one of three independent RFC complexes. By chromatographic methods, Ctf7p/Eco1p was found to associate with Chl12/Ctf18p and with Rfc2p, Rfc3p, Rfc4p, and Rfc5p. The association between Ctf7p/Eco1p and this RFC complex is biologically relevant in that (i) Ctf7p/Eco1p cosediments with Chl12p/Ctf18p in vivo and (ii) rfc5-1 mutant cells exhibit precocious sister separation. Previous studies revealed that Rfc1p or Rad24p associates with Rfc2p to Rfc5p to form two other RFC complexes independent of Ctf18p-RFC complexes. These Rfc1p-RFC and Rad24p-RFC complexes function in DNA replication or repair and DNA damage checkpoint pathways. Importantly, Ctf7p/Eco1p also associates with Rfc1p and Rad24p, suggesting that these RFC complexes also play critical roles in cohesion establishment. The associations between Ctf7p/Eco1p and RFC subunits provide novel evidence regarding the physical linkage between cohesion establishment and DNA replication. Furthermore, the association of Ctf7p/Eco1p with each of three RFC complexes supplies new insights into the functional redundancy of RFC complexes in cohesion establishment.


1999 ◽  
Vol 19 (2) ◽  
pp. 1038-1048 ◽  
Author(s):  
Hiroyuki Tanaka ◽  
Koichi Tanaka ◽  
Hiroshi Murakami ◽  
Hiroto Okayama

ABSTRACT At the nonpermissive temperature the fission yeastcdc24-M38 mutant arrests in the cell cycle with incomplete DNA replication as indicated by pulsed-field gel electrophoresis. Thecdc24 + gene encodes a 501-amino-acid protein with no significant homology to any known proteins. The temperature-sensitive cdc24 mutant is effectively rescued by pcn1 +, rfc1 + (a fission yeast homologue of RFC1), andhhp1 +, which encode the proliferating cell nuclear antigen (PCNA), the large subunit of replication factor C (RFC), and a casein kinase I involved in DNA damage repair, respectively. The Cdc24 protein binds PCNA and RFC1 in vivo, and the domains essential for Cdc24 function and for RFC1 and PCNA binding colocalize in the N-terminal two-thirds of the molecule. In addition,cdc24 + genetically interacts with the gene encoding the catalytic subunit of DNA polymerase ɛ, which is stimulated by PCNA and RFC, and with those encoding the fission yeast counterparts of Mcm2, Mcm4, and Mcm10. These results indicate that Cdc24 is an RFC- and PCNA-interacting factor required for DNA replication and might serve as a target for regulation.


1986 ◽  
Vol 6 (12) ◽  
pp. 4594-4601
Author(s):  
J J Dermody ◽  
B E Wojcik ◽  
H Du ◽  
H L Ozer

We described a strategy which facilitates the identification of cell mutants which are restricted in DNA synthesis in a temperature-dependent manner. A collection of over 200 cell mutants temperature-sensitive for growth was isolated in established Chinese hamster cell lines (CHO and V79) by a variety of selective and nonselective techniques. Approximately 10% of these mutants were identified as ts DNA- based on differential inhibition of macromolecular synthesis at the restrictive temperature (39 degrees C) as assessed by incorporation of [3H]thymidine and [35S]methionine. Nine such mutants, selected for further study, demonstrated rapid shutoff of DNA replication at 39 degrees C. Infections with two classes of DNA viruses extensively dependent on host-cell functions for their replication were used to distinguish defects in DNA synthesis itself from those predominantly affecting other aspects of DNA replication. All cell mutants supported human adenovirus type 2 (Ad2) and mouse polyomavirus DNA synthesis at the permissive temperature. Five of the nine mutants (JB3-B, JB3-O, JB7-K, JB8-D, and JB11-J) restricted polyomavirus DNA replication upon transfection with viral sequences at 33 degrees C and subsequent shift to 39 degrees C either before or after the onset of viral DNA synthesis. Only one of these mutants (JB3-B) also restricted Ad2 DNA synthesis after virion infection under comparable conditions. No mutant was both restrictive for Ad2 and permissive for polyomavirus DNA synthesis at 39 degrees C. The differential effect of these cell mutants on viral DNA synthesis is expected to assist subsequent definition of the biochemical defect responsible.


Genetics ◽  
1998 ◽  
Vol 148 (3) ◽  
pp. 989-1005 ◽  
Author(s):  
Keiko Umezu ◽  
Neal Sugawara ◽  
Clark Chen ◽  
James E Haber ◽  
Richard D Kolodner

Abstract Replication protein A (RPA) is a single-stranded DNA-binding protein identified as an essential factor for SV40 DNA replication in vitro. To understand the in vivo functions of RPA, we mutagenized the Saccharomyces cerevisiae RFA1 gene and identified 19 ultraviolet light (UV) irradiation- and methyl methane sulfonate (MMS)-sensitive mutants and 5 temperature-sensitive mutants. The UV- and MMS-sensitive mutants showed up to 104 to 105 times increased sensitivity to these agents. Some of the UV- and MMS-sensitive mutants were killed by an HO-induced double-strand break at MAT. Physical analysis of recombination in one UV- and MMS-sensitive rfa1 mutant demonstrated that it was defective for mating type switching and single-strand annealing recombination. Two temperature-sensitive mutants were characterized in detail, and at the restrictive temperature were found to have an arrest phenotype and DNA content indicative of incomplete DNA replication. DNA sequence analysis indicated that most of the mutations altered amino acids that were conserved between yeast, human, and Xenopus RPA1. Taken together, we conclude that RPA1 has multiple roles in vivo and functions in DNA replication, repair, and recombination, like the single-stranded DNA-binding proteins of bacteria and phages.


2003 ◽  
Vol 23 (2) ◽  
pp. 721-732 ◽  
Author(s):  
Lisa A. Anderson ◽  
Neil D. Perkins

ABSTRACT The RelA (p65) subunit of NF-κB is an important regulator of inflammation, proliferation, and apoptosis. We have discovered that the large subunit, p140, of replication factor C (RFC) can function as a regulator of RelA. RFC is a clamp loader, facilitating the addition and removal of proliferating-cell nuclear antigen from DNA during replication and repair but can also interact directly with the retinoblastoma tumor suppressor protein and the transcription factor C/EBPα. We find that RFC (p140) interacts with RelA both in vitro and in vivo and stimulates RelA transactivation. In contrast, coexpression of fragments of RFC (p140) that mediate the interaction with RelA results in transcriptional inhibition. The significance of this regulation was confirmed by using short interfering RNA oligonucleotides targeted to RFC (p140). Down regulation of endogenous RFC (p140) inhibits expression from a chromosomally integrated reporter plasmid induced by endogenous, TNF-α-activated NF-κB. Dominant negative fragments of RFC (p140) also cooperate with overexpressed RelA to induce cell death. Interestingly, RFC (p140) also interacts with the tumor suppressor p53. Taken together, these observations suggest that, in addition to its previously described function in DNA replication and repair, RFC (p140) has an important role as a regulator of transcription and NF-κB activity.


1988 ◽  
Vol 106 (4) ◽  
pp. 1171-1183 ◽  
Author(s):  
T Hirano ◽  
Y Hiraoka ◽  
M Yanagida

A temperature-sensitive mutant nuc2-663 of the fission yeast Schizosaccharomyces pombe specifically blocks mitotic spindle elongation at restrictive temperature so that nuclei in arrested cells contain a short uniform spindle (approximately 3-micron long), which runs through a metaphase plate-like structure consisting of three condensed chromosomes. In the wild-type or in the mutant cells at permissive temperature, the spindle is fully extended approximately 15-micron long in anaphase. The nuc2' gene was cloned in a 2.4-kb genomic DNA fragment by transformation, and its complete nucleotide sequence was determined. Its coding region predicts a 665-residues internally repeating protein (76.250 mol wt). By immunoblots using anti-sera raised against lacZ-nuc2+ fused proteins, a polypeptide (designated p67; 67,000 mol wt) encoded by nuc2+ is detected in the wild-type S. pombe extracts; the amount of p67 is greatly increased when multi-copy or high-expression plasmids carrying the nuc2+ gene are introduced into the S. pombe cells. Cellular fractionation and Percoll gradient centrifugation combined with immunoblotting show that p67 cofractionates with nuclei and is enriched in resistant structure that is insoluble in 2 M NaCl, 25 mM lithium 3,5'-diiodosalicylate, and 1% Triton but is soluble in 8 M urea. In nuc2 mutant cells, however, soluble p76, perhaps an unprocessed precursor, accumulates in addition to insoluble p67. The role of nuc2+ gene may be to interconnect nuclear and cytoskeletal functions in chromosome separation.


2012 ◽  
Vol 287 (44) ◽  
pp. 36711-36719 ◽  
Author(s):  
Zhimin Peng ◽  
Zhongping Liao ◽  
Barbara Dziegielewska ◽  
Yoshi Matsumoto ◽  
Stefani Thomas ◽  
...  

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