Abstract
We report the structure of the micronuclear (germline) gene encoding the large catalytic subunit of DNA polymerase alpha (DNA pol alpha) in the ciliate Oxytricha nova. It contains 44 internal eliminated segments (IESs) that divide the gene into 45 macronuclear-destined segments (MDSs) that are in a non-randomly scrambled order with an inversion near the gene center. Odd numbered MDSs 29-43, containing 230 bp out of a total of 4938 bp of macronuclear sequence, are missing from the 14 kb cloned gene. The missing MDSs have not been located but are at least several kilobases from the main body of the gene. The remarkably scrambled DNA pol alpha gene must be extensively cut, re-ordered and spliced and an inversion must occur to produce an unscrambled, functional version of the gene during development of a new macronucleus. Unscrambling is hypothesized to occur by a homologous recombination mechanism guided by repeat sequences at MDS ends.
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Selected References
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- Anderson R. C., Lindauer K. R., Prescott D. M. A gene-sized DNA molecule encoding heat-shock protein 70 in Oxytricha nova. Gene. 1996 Feb 2;168(1):103–107. doi: 10.1016/0378-1119(95)00735-0. [DOI] [PubMed] [Google Scholar]
- Damagnez V., Tillit J., de Recondo A. M., Baldacci G. The POL1 gene from the fission yeast, Schizosaccharomyces pombe, shows conserved amino acid blocks specific for eukaryotic DNA polymerases alpha. Mol Gen Genet. 1991 Apr;226(1-2):182–189. doi: 10.1007/BF00273602. [DOI] [PubMed] [Google Scholar]
- Klobutcher L. A., Jahn C. L., Prescott D. M. Internal sequences are eliminated from genes during macronuclear development in the ciliated protozoan Oxytricha nova. Cell. 1984 Apr;36(4):1045–1055. doi: 10.1016/0092-8674(84)90054-0. [DOI] [PubMed] [Google Scholar]
- Mansour S. J., Hoffman D. C., Prescott D. M. A gene-sized DNA molecule encoding the catalytic subunit of DNA polymerase alpha in the macronucleus of Oxytricha nova. Gene. 1994 Jul 8;144(2):155–161. doi: 10.1016/0378-1119(94)90373-5. [DOI] [PubMed] [Google Scholar]
- Mitcham J. L., Lynn A. J., Prescott D. M. Analysis of a scrambled gene: the gene encoding alpha-telomere-binding protein in Oxytricha nova. Genes Dev. 1992 May;6(5):788–800. doi: 10.1101/gad.6.5.788. [DOI] [PubMed] [Google Scholar]
- Mitcham J. L., Prescott D. M., Miller M. K. The micronuclear gene encoding beta-telomere binding protein in Oxytricha nova. J Eukaryot Microbiol. 1994 Sep-Oct;41(5):478–480. doi: 10.1111/j.1550-7408.1994.tb06045.x. [DOI] [PubMed] [Google Scholar]
- Prescott D. M., Greslin A. F. Scrambled actin I gene in the micronucleus of Oxytricha nova. Dev Genet. 1992;13(1):66–74. doi: 10.1002/dvg.1020130111. [DOI] [PubMed] [Google Scholar]
- Ribas-Aparicio R. M., Sparkowski J. J., Proulx A. E., Mitchell J. D., Klobutcher L. A. Nucleic acid splicing events occur frequently during macronuclear development in the protozoan Oxytricha nova and involve the elimination of unique DNA. Genes Dev. 1987 Jun;1(4):323–336. doi: 10.1101/gad.1.4.323. [DOI] [PubMed] [Google Scholar]
- Wang T. S., Wong S. W., Korn D. Human DNA polymerase alpha: predicted functional domains and relationships with viral DNA polymerases. FASEB J. 1989 Jan;3(1):14–21. doi: 10.1096/fasebj.3.1.2642867. [DOI] [PubMed] [Google Scholar]