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Classes of autonomously replicating sequences are found among early-replicating monkey DNA.
S Landry1, M Zannis-Hadjopoulos
1McGill Cancer Center, McGill University, Montréal, Canada.
Biochimica Et Biophysica Acta
|February 16, 1991
Summary
Researchers identified thirteen new origin-enriched sequences (ORS) capable of autonomous replication from monkey DNA. These findings suggest diverse mammalian replication origins rely on structural features, not specific sequences, for activation.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Origin-enriched sequences (ORS) are crucial for DNA replication.
- Previous studies identified ORS from early replicating monkey DNA.
Purpose of the Study:
- To identify and characterize new autonomously replicating ORS from monkey DNA.
- To investigate the sequence features and classification of mammalian replication origins.
Main Methods:
- Isolation and screening of 100 ORS clones from monkey DNA.
- Assaying autonomous replication via transient episomal replication in HeLa cells.
- Utilizing DpnI resistance and bromodeoxyuridine (BrdUrd) substitution assays for DNA replication analysis.
- Nucleotide sequence analysis of functional ORS clones.
Main Results:
- Thirteen new independent ORS clones capable of autonomous replication were identified.
- Four clones were identified using probes for previously characterized ORS (3, 8, 9, 12).
- Nine novel functional ORS were found among randomly selected clones.
- Sequence analysis revealed AT-rich regions and inverted repeats in most functional ORS.
- No extensive sequence homologies were found between new ORS, except for alpha-satellite and Alu repetitive sequences in some.
- Identified ORS belong to different classes: highly/moderately repetitive and unique.
Conclusions:
- Mammalian replication origins can be classified into distinct repetitive and unique categories.
- The activation of these origins is likely dependent on structural determinants rather than specific sequences.