Skip to main content
PMC home page
Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1983 May;80(10):3025–3029. doi: 10.1073/pnas.80.10.3025

Differential methylation of chloroplast DNA regulates maternal inheritance in a methylated mutant of Chlamydomonas

Ruth Sager 1, Constance Grabowy 1
PMCID: PMC393966  PMID: 16593314

Abstract

In Chlamydomonas, the maternal inheritance of chloroplast genes correlates with the differential methylation of chloroplast DNA (chlDNA) in females (mt+) but not in males (mt-). Our previous studies have supported our methylation-restriction model in which the maternal transmission is accounted for by the differential methylation in gametes which protects female but not male chlDNA from degradation during zygote formation. In the mutant me-1 [Bolen, P. L., Grant, D. M., Swinton, D., Boynton, J. E. & Gillham, N. W. (1982) Cell 28, 335-343], chlDNA of vegetative cells of both mating types is heavily methylated even before gametogenesis; nonetheless, maternal inheritance occurs in mutants as in wild type. To investigate the mechanism of maternal inheritance in the me-1 mutant, we have compared restriction fragment patterns after agarose gel electrophoresis of chlDNAs from mutant vegetative cells and gametes with those from wild type, by using a set of 32 restriction enzymes of which 17 were methylation-sensitive in this system. We find that additional methylation occurs during gametogenesis in the mutant female (mt+) but not in the corresponding male (mt-). Thus, gamete-specific, mating-type-specific methylation occurs in the me-1 mutant as in the wild type, consistent with our methylation-restriction model. In the me-1 mutant, gametic methylation occurs on a background of vegetative cell methylation not present in wild-type cells and irrelevant to the regulation of chloroplast inheritance. Comparison of the me-1 mutation with the mat-1 mutation [Sager, R., Grabowy, C. & Sano, H. (1981) Cell 24, 41-47] provides evidence for the existence of two different chlDNA methylation control systems: mat-1, linked to the mating type locus and regulating the mating-type-specific methylation that correlates with maternal inheritance, and me-1, unlinked to the mating type locus and unrelated to the regulation of maternal inheritance.

Keywords: gametogenesis, gel electrophoresis, methylation-sensitive restriction enzymes

Full text

PDF
3025

Images in this article

3027Image
on p.3027
3028Image
on p.3028
3028Image
on p.3028
3028Image
on p.3028
3028Image
on p.3028
3028Image
on p.3028

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Arber W. DNA modification and restriction. Prog Nucleic Acid Res Mol Biol. 1974;14(0):1–37. doi: 10.1016/s0079-6603(08)60204-4. [DOI] [PubMed] [Google Scholar]
  2. Bolen P. L., Grant D. M., Swinton D., Boynton J. E., Gillham N. W. Extensive methylation of chloroplast DNA by a nuclear gene mutation does not affect chloroplast gene transmission in chlamydomonas. Cell. 1982 Feb;28(2):335–343. doi: 10.1016/0092-8674(82)90351-8. [DOI] [PubMed] [Google Scholar]
  3. Burton W. G., Grabowy C. T., Sager R. Role of methylation in the modification and restriction of chloroplast DNA in Chlamydomonas. Proc Natl Acad Sci U S A. 1979 Mar;76(3):1390–1394. doi: 10.1073/pnas.76.3.1390. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Glickman B., van den Elsen P., Radman M. Induced mutagenesis in dam- mutants of Escherichia coli: a role for 6-methyladenine residues in mutation avoidance. Mol Gen Genet. 1978 Jul 25;163(3):307–312. doi: 10.1007/BF00271960. [DOI] [PubMed] [Google Scholar]
  5. Meselson M., Yuan R., Heywood J. Restriction and modification of DNA. Annu Rev Biochem. 1972;41:447–466. doi: 10.1146/annurev.bi.41.070172.002311. [DOI] [PubMed] [Google Scholar]
  6. Royer H. D., Sager R. Methylation of chloroplast DNAs in the life cycle of Chlamydomonas. Proc Natl Acad Sci U S A. 1979 Nov;76(11):5794–5798. doi: 10.1073/pnas.76.11.5794. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Sager R., Grabowy C., Sano H. The mat-1 gene in Chlamydomonas regulates DNA methylation during gametogenesis. Cell. 1981 Apr;24(1):41–47. doi: 10.1016/0092-8674(81)90499-2. [DOI] [PubMed] [Google Scholar]
  8. Sager R., Lane D. Molecular basis of maternal inheritance. Proc Natl Acad Sci U S A. 1972 Sep;69(9):2410–2413. doi: 10.1073/pnas.69.9.2410. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Sager R., Ramanis Z. Mutations that alter the transmission of chloroplast genes in Chlamydomonas. Proc Natl Acad Sci U S A. 1974 Dec;71(12):4698–4702. doi: 10.1073/pnas.71.12.4698. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Sano H., Grabowy C., Sager R. Differential activity of DNA methyltransferase in the life cycle of Chlamydomonas reinhardi. Proc Natl Acad Sci U S A. 1981 May;78(5):3118–3122. doi: 10.1073/pnas.78.5.3118. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Sano H., Royer H. D., Sager R. Identification of 5-methylcytosine in DNA fragments immobilized on nitrocellulose paper. Proc Natl Acad Sci U S A. 1980 Jun;77(6):3581–3585. doi: 10.1073/pnas.77.6.3581. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Yuan R. Structure and mechanism of multifunctional restriction endonucleases. Annu Rev Biochem. 1981;50:285–319. doi: 10.1146/annurev.bi.50.070181.001441. [DOI] [PubMed] [Google Scholar]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

RESOURCES