scholarly journals A mammalian origin of bidirectional DNA replication within the Chinese hamster RPS14 locus.

1994 ◽  
Vol 14 (9) ◽  
pp. 5628-5635 ◽  
Author(s):  
E S Tasheva ◽  
D J Roufa
Keyword(s):  
Dna Replication ◽  
Chinese Hamster ◽  
Housekeeping Gene ◽  
Single Copy ◽  
The Other ◽  
Replication Origins ◽  
Chromosomal Replication ◽  
Dna Binding Sites ◽  
Sequence Encoding ◽  
Copy Dna

Two complementary experimental approaches have been used to identify a chromosomal origin of bidirectional DNA replication within or immediately downstream of the Chinese hamster ribosomal protein S14 gene (RPS14). The replication origin, designated oriS14, maps within a 1.6- to 2.0-kbp region of RPS14 that includes the gene's third and fourth introns, exons IV plus V, and approximately 500 bp of proximal downstream flanking DNA. The nucleic acid sequence encoding oriS14 closely resembles the other mammalian chromosomal replication origins whose primary structures are known. It contains DNA binding sites for a large number of transcription factors, replication proteins, and mammalian oncogenes as well as several dinucleotide repeat motifs, an AT-rich region, and a sequence that is likely to bend the DNA. In contrast to the other well-characterized mammalian replication origins, which are autosomal and therefore carried as two copies per somatic cell, oriS14 is encoded by single-copy DNA within a hemizygous segment of chromosome 2q in CHO-K1 cells. Also, other known mammalian replication origins are situated in nontranscribed, intergenic DNA, whereas the DNA sequence encoding oriS14 substantially overlaps the transcribed portion of a constitutively expressed housekeeping gene.

A mammalian origin of bidirectional DNA replication within the Chinese hamster RPS14 locus

1994 ◽  
Vol 14 (9) ◽  
pp. 5628-5635
Author(s):  
E S Tasheva ◽  
D J Roufa
Keyword(s):  
Dna Replication ◽  
Chinese Hamster ◽  
Housekeeping Gene ◽  
Single Copy ◽  
The Other ◽  
Replication Origins ◽  
Chromosomal Replication ◽  
Dna Binding Sites ◽  
Sequence Encoding ◽  
Copy Dna

Two complementary experimental approaches have been used to identify a chromosomal origin of bidirectional DNA replication within or immediately downstream of the Chinese hamster ribosomal protein S14 gene (RPS14). The replication origin, designated oriS14, maps within a 1.6- to 2.0-kbp region of RPS14 that includes the gene's third and fourth introns, exons IV plus V, and approximately 500 bp of proximal downstream flanking DNA. The nucleic acid sequence encoding oriS14 closely resembles the other mammalian chromosomal replication origins whose primary structures are known. It contains DNA binding sites for a large number of transcription factors, replication proteins, and mammalian oncogenes as well as several dinucleotide repeat motifs, an AT-rich region, and a sequence that is likely to bend the DNA. In contrast to the other well-characterized mammalian replication origins, which are autosomal and therefore carried as two copies per somatic cell, oriS14 is encoded by single-copy DNA within a hemizygous segment of chromosome 2q in CHO-K1 cells. Also, other known mammalian replication origins are situated in nontranscribed, intergenic DNA, whereas the DNA sequence encoding oriS14 substantially overlaps the transcribed portion of a constitutively expressed housekeeping gene.

Densely methylated DNA islands in mammalian chromosomal replication origins

1994 ◽  
Vol 14 (9) ◽  
pp. 5636-5644
Author(s):  
E S Tasheva ◽  
D J Roufa
Keyword(s):  
Cell Growth ◽  
Dna Sequence ◽  
Chemical Method ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
The Other ◽  
Replication Origins ◽  
Chromosomal Replication ◽  
Cpg Dinucleotides ◽  
Methylated Dna

Densely methylated DNA sequence islands, designated DMIs, have been observed in two Chinese hamster cell chromosomal replication origins by using a PCR-based chemical method of detection. One of the origins, oriS14, is located within or adjacent to the coding sequence for ribosomal protein S14 on chromosome 2q, and the other, ori-beta, is approximately 17 kbp downstream of the dhfr (dihydrofolic acid reductase) locus on chromosome 2p. The DMI in oriS14 is 127 bp long, and the DMI in ori-beta is 516 bp long. Both DMIs are bilaterally methylated (i.e., all dCs are modified to 5-methyl dC) only in cells that are replicating their DNA. When cell growth and DNA replication are arrested, methylation of CpA, CpT, and CpC dinucleotides is lost and the sequence islands display only a subset of their originally methylated CpG dinucleotides. Several possible roles for DMI-mediated regulation of mammalian chromosomal origins are considered.

scholarly journals Densely methylated DNA islands in mammalian chromosomal replication origins.

1994 ◽  
Vol 14 (9) ◽  
pp. 5636-5644 ◽  
Author(s):  
E S Tasheva ◽  
D J Roufa
Keyword(s):  
Cell Growth ◽  
Dna Sequence ◽  
Chemical Method ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
The Other ◽  
Replication Origins ◽  
Chromosomal Replication ◽  
Cpg Dinucleotides ◽  
Methylated Dna

Densely methylated DNA sequence islands, designated DMIs, have been observed in two Chinese hamster cell chromosomal replication origins by using a PCR-based chemical method of detection. One of the origins, oriS14, is located within or adjacent to the coding sequence for ribosomal protein S14 on chromosome 2q, and the other, ori-beta, is approximately 17 kbp downstream of the dhfr (dihydrofolic acid reductase) locus on chromosome 2p. The DMI in oriS14 is 127 bp long, and the DMI in ori-beta is 516 bp long. Both DMIs are bilaterally methylated (i.e., all dCs are modified to 5-methyl dC) only in cells that are replicating their DNA. When cell growth and DNA replication are arrested, methylation of CpA, CpT, and CpC dinucleotides is lost and the sequence islands display only a subset of their originally methylated CpG dinucleotides. Several possible roles for DMI-mediated regulation of mammalian chromosomal origins are considered.

scholarly journals Completion of Replication Map of Saccharomyces cerevisiae Chromosome III

2001 ◽  
Vol 12 (11) ◽  
pp. 3317-3327 ◽  
Author(s):  
Arkadi Poloumienko ◽  
Ann Dershowitz ◽  
Jitakshi De ◽  
Carol S. Newlon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Replication ◽  
Complete Analysis ◽  
Replication Origins ◽  
Chromosomal Dna ◽  
Chromosomal Replication ◽  
Autonomously Replicating Sequence ◽  
Eukaryotic Chromosome ◽  
Ars Elements ◽  
Chromosome Iii

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.

scholarly journals High-resolution mapping of the origin of DNA replication in the hamster dihydrofolate reductase gene domain by competitive PCR.

1996 ◽  
Vol 16 (10) ◽  
pp. 5358-5364 ◽  
Author(s):  
C Pelizon ◽  
S Diviacco ◽  
A Falaschi ◽  
M Giacca
Keyword(s):  
Dna Replication ◽  
Dihydrofolate Reductase ◽  
Cultured Cells ◽  
Chinese Hamster ◽  
Single Copy ◽  
Genomic Region ◽  
Competitive Pcr ◽  
Dhfr Gene ◽  
Mapping Procedure ◽  
Dna Replication Origin

By the use of a highly sensitive mapping procedure allowing the identification of the start sites of DNA replication in single-copy genomic regions of untreated, exponentially growing cultured cells (M. Giacca, L. Zentilin, P. Norio, S. Diviacco, D. Dimitrova, G. Contreas, G. Biamonti, G. Perini, F. Weighardt, S. Riva, and A. Falaschi, Proc. Natl. Acad. Sci. USA 91:7119-7123, 1994), the pattern of DNA replication of the Chinese hamster dihydrofolate reductase (DHFR) gene domain was investigated. The method entails the purification of short stretches of nascent DNA issuing from DNA replication origin regions and quantification, within this sample, of the abundance of different adjacent segments by competitive PCR. Distribution of marker abundance peaks around the site from which newly synthesized DNA had emanated. The results obtained by analysis of the genomic region downstream of the DHFR single-copy gene in asynchronous cultures of hamster CHO K1 cells are consistent with the presence of a single start site for DNA replication, located approximately 17 kb downstream of the gene. This site is coincident with the one detected by other studies using different techniques in CHO cell lines containing an amplified DHFR gene domain.

Chromosomal DNA replication initiates at the same origins in meiosis and mitosis

1994 ◽  
Vol 14 (5) ◽  
pp. 3524-3534
Author(s):  
I Collins ◽  
C S Newlon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Replication ◽  
S Phase ◽  
Replication Origins ◽  
Chromosomal Dna ◽  
Chromosomal Replication ◽  
Yeast Saccharomyces Cerevisiae ◽  
Autonomously Replicating Sequence ◽  
Ars Elements ◽  
Chromosome Iii

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.

Emetine resistance of Chinese hamster cells: structures of wild-type and mutant ribosomal protein S14 mRNAs

1985 ◽  
Vol 5 (7) ◽  
pp. 1655-1659
Author(s):  
D D Rhoads ◽  
D J Roufa
Keyword(s):  
Ribosomal Protein ◽  
Ribosomal Subunit ◽  
Chinese Hamster ◽  
Housekeeping Gene ◽  
Single Copy ◽  
Wild Type ◽  
Cho Cell ◽  
40S Ribosomal Subunit ◽  
And Function ◽  
Physical And Chemical

The Chinese hamster ovary (CHO) cell 40S ribosomal subunit protein S14 provides a unique opportunity to investigate an important mammalian housekeeping gene and its mRNA and protein products. The S14 gene appears to be single copy, and CHO cell S14 mutants have been isolated as emetine-resistant (emtB) clones in tissue culture. Thus, S14 is the only mammalian ribosomal protein whose gene structure and function are amenable to straightforward genetic and biochemical analysis. Recently, we isolated a wild-type Chinese hamster lung cell cDNA clone, pCS14-1, including an almost complete copy of the ribosomal protein S14 message (N. Nakamichi, D. D. Rhoads, and D. J. Roufa, J. Biol. Chem. 258: 13236-13242, 1983). Here we describe comparable cDNAs from wild-type and emtB CHO cells. We report both mRNA and polypeptide sequences of the wild-type and mutant ribosomal protein transcripts. As a consequence of the genetic methods used to obtain our emetine-resistant mutants, the emtB S14 cDNAs differ from wild-type cDNA by single-base changes. Physical and chemical features of polypeptides encoded by the cDNAs are consistent with well-characterized S14 protein polymorphisms. The three emtB mutations analyzed affect two adjacent arginine codons within the very basic S14 carboxyl region, indicating a significant role for this portion of the protein in the function and architecture of the mammalian 40S ribosomal subunit.

scholarly journals Emetine resistance of Chinese hamster cells: structures of wild-type and mutant ribosomal protein S14 mRNAs.

1985 ◽  
Vol 5 (7) ◽  
pp. 1655-1659 ◽  
Author(s):  
D D Rhoads ◽  
D J Roufa
Keyword(s):  
Ribosomal Protein ◽  
Ribosomal Subunit ◽  
Chinese Hamster ◽  
Housekeeping Gene ◽  
Single Copy ◽  
Wild Type ◽  
Cho Cell ◽  
40S Ribosomal Subunit ◽  
And Function ◽  
Physical And Chemical

The Chinese hamster ovary (CHO) cell 40S ribosomal subunit protein S14 provides a unique opportunity to investigate an important mammalian housekeeping gene and its mRNA and protein products. The S14 gene appears to be single copy, and CHO cell S14 mutants have been isolated as emetine-resistant (emtB) clones in tissue culture. Thus, S14 is the only mammalian ribosomal protein whose gene structure and function are amenable to straightforward genetic and biochemical analysis. Recently, we isolated a wild-type Chinese hamster lung cell cDNA clone, pCS14-1, including an almost complete copy of the ribosomal protein S14 message (N. Nakamichi, D. D. Rhoads, and D. J. Roufa, J. Biol. Chem. 258: 13236-13242, 1983). Here we describe comparable cDNAs from wild-type and emtB CHO cells. We report both mRNA and polypeptide sequences of the wild-type and mutant ribosomal protein transcripts. As a consequence of the genetic methods used to obtain our emetine-resistant mutants, the emtB S14 cDNAs differ from wild-type cDNA by single-base changes. Physical and chemical features of polypeptides encoded by the cDNAs are consistent with well-characterized S14 protein polymorphisms. The three emtB mutations analyzed affect two adjacent arginine codons within the very basic S14 carboxyl region, indicating a significant role for this portion of the protein in the function and architecture of the mammalian 40S ribosomal subunit.

scholarly journals Identification of an origin of bidirectional DNA replication in the ubiquitously expressed mammalian CAD gene.

1995 ◽  
Vol 15 (8) ◽  
pp. 4136-4148 ◽  
Author(s):  
R E Kelly ◽  
M L DeRose ◽  
B W Draper ◽  
G M Wahl
Keyword(s):  
Dna Replication ◽  
Syrian Hamster ◽  
De Novo ◽  
Chinese Hamster ◽  
Specific Inhibitor ◽  
Housekeeping Gene ◽  
Replication Initiation ◽  
Transcriptional Unit ◽  
Carbamoyl Phosphate ◽  
Cad Gene

Most DNA replication origins in eukaryotes localize to nontranscribed regions, and there are no reports of origins within constitutively expressed genes. This observation has led to the proposal that there may be an incompatibility between origin function and location within a ubiquitously expressed gene. The biochemical and functional evidence presented here demonstrates that an origin of bidirectional replication (OBR) resides within the constitutively expressed housekeeping gene CAD, which encodes the first three reactions of de novo uridine biosynthesis (carbamoyl-phosphate synthetase, aspartate carbamoyltransferase, and dihydroorotase). The OBR was localized to a 5-kb region near the center of the Syrian hamster CAD transcriptional unit. DNA replication initiates within this region in the single-copy CAD gene in Syrian baby hamster kidney cells and in the large chromosomal amplicons that were generated after selection with N-phosphonacetyl-L-aspartate, a specific inhibitor of CAD. DNA synthesis also initiates within this OBR in autonomously replicating extrachromosomal amplicons (CAD episomes) located in an N-phosphonacetyl-L-aspartate-resistant clone (5P20) of CHOK1 cells. CAD episomes consist entirely of a multimer of Syrian hamster CAD cosmid sequences (cCAD1). These data limit the functional unit of replication initiation and timing control to the 42 kb of Syrian hamster sequences contained in cCAD1. In addition, the data indicate that the origin recognition machinery is conserved across species, since the same OBR region functions in both Syrian and Chinese hamster cells. Importantly, while cCAD1 exhibits characteristics of a complete replicon, we have not detected autonomous replication directly following transfection. Since the CAD episome was generated after excision of chromosomally integrated transfected cCAD1 sequences, we propose that prior localization within a chromosome may be necessary to "license" some biochemically defined OBRs to render them functional.

scholarly journals Chromosomal DNA replication initiates at the same origins in meiosis and mitosis.

1994 ◽  
Vol 14 (5) ◽  
pp. 3524-3534 ◽  
Author(s):  
I Collins ◽  
C S Newlon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Replication ◽  
S Phase ◽  
Replication Origins ◽  
Chromosomal Dna ◽  
Chromosomal Replication ◽  
Yeast Saccharomyces Cerevisiae ◽  
Autonomously Replicating Sequence ◽  
Ars Elements ◽  
Chromosome Iii

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.

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