scholarly journals Activation of Silent Replication Origins at Autonomously Replicating Sequence Elements near the HML Locus in Budding Yeast

1999 ◽  
Vol 19 (9) ◽  
pp. 6098-6109 ◽  
Author(s):  
Marija Vujcic ◽  
Charles A. Miller ◽  
David Kowalski

ABSTRACT In the budding yeast, Saccharomyces cerevisiae, replicators can function outside the chromosome as autonomously replicating sequence (ARS) elements; however, within chromosome III, certain ARSs near the transcriptionally silent HML locus show no replication origin activity. Two of these ARSs comprise the transcriptional silencers E (ARS301) and I (ARS302). Another, ARS303, resides betweenHML and the CHA1 gene, and its function is not known. Here we further localized and characterized ARS303and in the process discovered a new ARS, ARS320. BothARS303 and ARS320 are competent as chromosomal replication origins since origin activity was seen when they were inserted at a different position in chromosome III. However, at their native locations, where the two ARSs are in a cluster withARS302, the I silencer, no replication origin activity was detected regardless of yeast mating type, special growth conditions that induce the transcriptionally repressed CHA1 gene,trans-acting mutations that abrogate transcriptional silencing at HML (sir3, orc5), orcis-acting mutations that delete the E and I silencers containing ARS elements. These results suggest that, for theHML ARS cluster (ARS303, ARS320, and ARS302), inactivity of origins is independent of local transcriptional silencing, even though origins and silencers share keycis- and trans-acting components. Surprisingly, deletion of active replication origins located 25 kb (ORI305) and 59 kb (ORI306) away led to detection of replication origin function at theHML ARS cluster, as well as at ARS301, the E silencer. Thus, replication origin silencing at HML ARSs is mediated by active replication origins residing at long distances fromHML in the chromosome. The distal active origins are known to fire early in S phase, and we propose that their inactivation delays replication fork arrival at HML, providing additional time for HML ARSs to fire as origins.

2001 ◽  
Vol 12 (11) ◽  
pp. 3317-3327 ◽  
Author(s):  
Arkadi Poloumienko ◽  
Ann Dershowitz ◽  
Jitakshi De ◽  
Carol S. Newlon

In Saccharomyces cerevisiae chromosomal DNA replication initiates at intervals of ∼40 kb and depends upon the activity of autonomously replicating sequence (ARS) elements. The identification of ARS elements and analysis of their function as chromosomal replication origins requires the use of functional assays because they are not sufficiently similar to identify by DNA sequence analysis. To complete the systematic identification of ARS elements onS. cerevisiae chromosome III, overlapping clones covering 140 kb of the right arm were tested for their ability to promote extrachromosomal maintenance of plasmids. Examination of chromosomal replication intermediates of each of the seven ARS elements identified revealed that their efficiencies of use as chromosomal replication origins varied widely, with four ARS elements active in ≤10% of cells in the population and two ARS elements active in ≥90% of the population. Together with our previous analysis of a 200-kb region of chromosome III, these data provide the first complete analysis of ARS elements and DNA replication origins on an entire eukaryotic chromosome.


1995 ◽  
Vol 73 (S1) ◽  
pp. 208-214 ◽  
Author(s):  
Carol S. Newlon

To understand how a eukaryotic chromosome is replicated, a systematic analysis of chromosome III of Saccharomyces cerevisiae has been undertaken. Replication origins are specified by autonomously replicating sequence (ARS) elements, whose sequences can be dissected using a simple plasmid assay. Only a subset of ARS elements are active as chromosomal replication origins. Replication origins are required for normal chromosome transmission, but they appear to be redundant; several origins can be deleted without affecting chromosome stability. Replication origin position has been conserved on chromosome III in diverged strains, suggesting that origin position is important for chromosome function. The inability of some ARS elements to function as chromosomal replication origins appears likely to result from chromosomal context or position effects. Replication termination occurs over broad regions between active replication origins. The position of termination can be altered by deleting origins, suggesting that no specific replication termination elements are required. Replication forks appear to move at a relatively constant rate through the chromosome. A replication pause site associated with the centromere results from the kinetochore protein complex that binds the centromere to mediate chromosome segregation. Key words: Saccharomyces cerevisiae, ARS elements, replication origins, replication termination, DNA replication intermediates.


1994 ◽  
Vol 14 (5) ◽  
pp. 3524-3534
Author(s):  
I Collins ◽  
C S Newlon

Autonomously replicating sequence (ARS) elements are identified by their ability to promote high-frequency transformation and extrachromosomal replication of plasmids in the yeast Saccharomyces cerevisiae. Six of the 14 ARS elements present in a 200-kb region of Saccharomyces cerevisiae chromosome III are mitotic chromosomal replication origins. The unexpected observation that eight ARS elements do not function at detectable levels as chromosomal replication origins during mitotic growth suggested that these ARS elements may function as chromosomal origins during premeiotic S phase. Two-dimensional agarose gel electrophoresis was used to map premeiotic replication origins in a 100-kb segment of chromosome III between HML and CEN3. The pattern of origin usage in premeiotic S phase was identical to that in mitotic S phase, with the possible exception of ARS308, which is an inefficient mitotic origin associated with CEN3. CEN3 was found to replicate during premeiotic S phase, demonstrating that the failure of sister chromatids to disjoin during the meiosis I division is not due to unreplicated centromeres. No origins were found in the DNA fragments without ARS function. Thus, in both mitosis and meiosis, chromosomal replication origins are coincident with ARS elements but not all ARS elements have chromosomal origin function. The efficiency of origin use and the patterns of replication termination are similar in meiosis and in mitosis. DNA replication termination occurs over a broad distance between active origins.


1994 ◽  
Vol 14 (5) ◽  
pp. 3524-3534 ◽  
Author(s):  
I Collins ◽  
C S Newlon

Autonomously replicating sequence (ARS) elements are identified by their ability to promote high-frequency transformation and extrachromosomal replication of plasmids in the yeast Saccharomyces cerevisiae. Six of the 14 ARS elements present in a 200-kb region of Saccharomyces cerevisiae chromosome III are mitotic chromosomal replication origins. The unexpected observation that eight ARS elements do not function at detectable levels as chromosomal replication origins during mitotic growth suggested that these ARS elements may function as chromosomal origins during premeiotic S phase. Two-dimensional agarose gel electrophoresis was used to map premeiotic replication origins in a 100-kb segment of chromosome III between HML and CEN3. The pattern of origin usage in premeiotic S phase was identical to that in mitotic S phase, with the possible exception of ARS308, which is an inefficient mitotic origin associated with CEN3. CEN3 was found to replicate during premeiotic S phase, demonstrating that the failure of sister chromatids to disjoin during the meiosis I division is not due to unreplicated centromeres. No origins were found in the DNA fragments without ARS function. Thus, in both mitosis and meiosis, chromosomal replication origins are coincident with ARS elements but not all ARS elements have chromosomal origin function. The efficiency of origin use and the patterns of replication termination are similar in meiosis and in mitosis. DNA replication termination occurs over a broad distance between active origins.


2001 ◽  
Vol 21 (15) ◽  
pp. 4938-4948 ◽  
Author(s):  
Yangzhou Wang ◽  
Marija Vujcic ◽  
David Kowalski

ABSTRACT Chromosomal replicators in budding yeast contain an autonomously replicating sequence (ARS) that functions in a plasmid, but certain ARSs are silent as replication origins in their natural chromosomal context. In chromosome III, the HML ARS cluster (ARS302-ARS303-ARS320) and ARS301 flank the transcriptionally silent mating-type locus HML, and all of these ARSs are silent as replication origins. ARS301 andARS302 function in transcriptional silencing mediated by the origin recognition complex (ORC) and a heterochromatin structure, while the functions of ARS303 and ARS320 are not known. In this work, we discovered replication fork pause sites at the HML ARS cluster and ARS301 by analyzing DNA replication intermediates from the chromosome via two-dimensional gel electrophoresis. The replication fork pause at the HML ARS cluster was independent of cis- andtrans-acting mutations that abrogate transcriptional silencing at HML. Deletion of the HML ARS cluster led to loss of the pause site. Insertion of a single, heterologous ARS (ARS305) in place of the HMLARS cluster reconstituted the pause site, as did multiple copies of DNA elements (A and B1) that bind ORC. The orc2-1 mutation, known to alter replication timing at origins, did not detectably affect the pause but activated the silent origin at the HML ARS cluster in a minority of cells. Delaying the time of fork arrival atHML led to the elimination of the pause sites at theHML ARS cluster and at the copy of ARS305inserted in place of the cluster. Loss of the pause sites was accompanied by activation of the silent origins in the majority of cells. Thus, replication fork movement near HML pauses at a silent origin which is competent for replication initiation but kept silent through Orc2p, a component of the replication initiator. Possible functions for replication fork pause sites in checkpoints, S-phase regulation, mating-type switching, and transcriptionally silent heterochromatin are discussed.


1994 ◽  
Vol 14 (11) ◽  
pp. 7652-7659
Author(s):  
J F Theis ◽  
C S Newlon

ARS307 is highly active as a replication origin in its native location on chromosome III of Saccharomyces cerevisiae. Its ability to confer autonomous replication activity on plasmids requires the presence of an 11-bp autonomously replicating sequence (ARS) consensus sequence (ACS), which is also required for chromosomal origin function, as well as approximately 100 bp of sequence flanking the ACS called domain B. To further define the sequences required for ARS function, a linker substitution mutagenesis of domain B was carried out. The mutations defined two sequences, B1 and B2, that contribute to ARS activity. Therefore, like ARS1, domain B of ARS307 is composed of functional subdomains. Constructs carrying mutations in the B1 element were used to replace the chromosomal copy of ARS307. These mutations caused a reduction in chromosomal origin activity, demonstrating that the B1 element is required for efficient chromosomal origin function.


1991 ◽  
Vol 11 (10) ◽  
pp. 5346-5355
Author(s):  
D D Dubey ◽  
L R Davis ◽  
S A Greenfeder ◽  
L Y Ong ◽  
J G Zhu ◽  
...  

The silent mating-type loci of Saccharomyces cerevisiae, HML and HMR, are flanked by transcriptional silencers that have ARS activity (i.e., they function as replication origins when in plasmids). To test whether these ARS elements are chromosomal origins, we mapped origins near HML (close to the left telomere of chromosome III). Our results indicate that the HML-associated ARS elements either do not function as chromosomal replication origins or do so at a frequency below our detection level, suggesting that replication from a silencer-associated origin in each S phase is not essential for the maintenance of transcriptional repression at HML. Our results also imply that the ability of a DNA fragment to function as an ARS element in a plasmid does not ensure its ability to function as an efficient chromosomal replication origin. Telomere proximity is not responsible for inactivating these ARS elements, because they are not detectably functional as chromosomal origins even in genetically modified strains in which they are far from the telomere.


2007 ◽  
Vol 27 (13) ◽  
pp. 4652-4663 ◽  
Author(s):  
Ann Dershowitz ◽  
Marylynn Snyder ◽  
Mohammed Sbia ◽  
Joan H. Skurnick ◽  
Loke Y. Ong ◽  
...  

ABSTRACT Replication origins in Saccharomyces cerevisiae are spaced at intervals of approximately 40 kb. However, both measurements of replication fork rate and studies of hypomorphic alleles of genes encoding replication initiation proteins suggest the question of whether replication origins are more closely spaced than should be required. We approached this question by systematically deleting replicators from chromosome III. The first significant increase in loss rate detected for the 315-kb full-length chromosome occurred only after all five efficient chromosomal replicators in the left two-thirds of the chromosome (ARS305, ARS306, ARS307, ARS309, and ARS310) had been deleted. The removal of the inefficient replicator ARS308 from this originless region caused little or no additional increase in loss rate. Chromosome fragmentations that removed the normally inactive replicators on the left end of the chromosome or the replicators distal to ARS310 on the right arm showed that both groups of replicators contribute significantly to the maintenance of the originless chromosome. Surprisingly, a 142-kb derivative of chromosome III, lacking all sequences that function as autonomously replicating sequence elements in plasmids, replicated and segregated properly 97% of the time. Both the replication initiation protein ORC and telomeres or a linear topology were required for the maintenance of chromosome fragments lacking replicators.


1989 ◽  
Vol 9 (10) ◽  
pp. 4488-4494 ◽  
Author(s):  
A E Reynolds ◽  
R M McCarroll ◽  
C S Newlon ◽  
W L Fangman

The replication of putative replication origins (ARS elements) was examined for 200 kilobases of chromosome III of Saccharomyces cerevisiae. By using synchronous cultures and transfers from dense to light isotope medium, the temporal pattern of mitotic DNA replication of eight fragments that contain ARSs was determined. ARS elements near the telomeres replicated late in S phase, while internal ARS elements replicated in the first half of S phase. The results suggest that some ARS elements in the chromosome may be inactive as replication origins. The actively expressed mating type locus, MAT, replicated early in S phase, while the silent cassettes, HML and HMR, replicated late. Unexpectedly, chromosome III sequences were found to replicate late in G1 at the arrest induced by the temperature-sensitive cdc7 allele.


2008 ◽  
Vol 28 (16) ◽  
pp. 5071-5081 ◽  
Author(s):  
FuJung Chang ◽  
James F. Theis ◽  
Jeremy Miller ◽  
Conrad A. Nieduszynski ◽  
Carol S. Newlon ◽  
...  

ABSTRACT Saccharomyces cerevisiae chromosome III encodes 11 autonomously replicating sequence (ARS) elements that function as chromosomal replicators. The essential 11-bp ARS consensus sequence (ACS) that binds the origin recognition complex (ORC) has been experimentally defined for most of these replicators but not for ARS318 (HMR-I), which is one of the HMR silencers. In this study, we performed a comprehensive linker scan analysis of ARS318. Unexpectedly, this replicator depends on a 9/11-bp match to the ACS that positions the ORC binding site only 6 bp away from an Abf1p binding site. Although a largely inactive replicator on the chromosome, ARS318 becomes active if the nearby HMR-E silencer is deleted. We also performed a multiple sequence alignment of confirmed replicators on chromosomes III, VI, and VII. This analysis revealed a highly conserved WTW motif 17 to 19 bp from the ACS that is functionally important and is apparent in the 228 phylogenetically conserved ARS elements among the six sensu stricto Saccharomyces species.


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