• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Logo of molcellbPermissionsJournals.ASM.orgJournalMCB ArticleJournal InfoAuthorsReviewers
Mol Cell Biol. Aug 1996; 16(8): 4305–4311.
PMCID: PMC231429

Essential and nonessential histone H2A variants in Tetrahymena thermophila.

Abstract

Although variants have been identified for every class of histone, their functions remain unknown. We have been studying the histone H2A variant hv1 in the ciliated protozoan Tetrahymena thermophila. Sequence analysis indicates that hv1 belongs to the H2A.F/Z type of histone variants. On the basis of the high degree of evolutionary conservation of this class of histones, they are proposed to have one or more distinct and essential functions that cannot be performed by their major H2A counterparts. Considerable evidence supports the hypothesis that the hv1 protein in T. thermophila and hv1-like proteins in other eukaryotes are associated with active chromatin. In T. thermophila, simple mass transformation and gene replacement techniques have recently become available. In this report, we demonstrate that either the HTA1 gene or the HTA2 gene, encoding the major H2As, can be completely replaced by disrupted genes in the polyploid, transcriptionally active macronucleus, indicating that neither of the two genes is essential. However, only some of the HTA3 genes encoding hv1 can be replaced by disrupted genes, indicating that the H2A.F/Z type variants have an essential function that cannot be performed by the major H2A genes. Thus, an essential gene in T. thermophila can be defined by the fact that it can be partially, but not completely, eliminated from the polyploid macronucleus. To our knowledge, this study represents the first use of gene disruption technology to study core histone gene function in any organism other than yeast and the first demonstration of an essential gene in T. thermophila using these methods. When a rescuing plasmid carrying a wild-type HTA3 gene was introduced into the T. thermophila cells, the endogenous chromosomal HTA3 could be completely replaced, defining a gene replacement strategy that can be used to analyze the function of essential genes.

Full Text

The Full Text of this article is available as a PDF (436K).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Allis CD, Glover CV, Bowen JK, Gorovsky MA. Histone variants specific to the transcriptionally active, amitotically dividing macronucleus of the unicellular eucaryote, Tetrahymena thermophila. Cell. 1980 Jul;20(3):609–617. [PubMed]
  • Allis CD, Richman R, Gorovsky MA, Ziegler YS, Touchstone B, Bradley WA, Cook RG. hv1 is an evolutionarily conserved H2A variant that is preferentially associated with active genes. J Biol Chem. 1986 Feb 5;261(4):1941–1948. [PubMed]
  • Allis CD, Ziegler YS, Gorovsky MA, Olmsted JB. A conserved histone variant enriched in nucleoli of mammalian cells. Cell. 1982 Nov;31(1):131–136. [PubMed]
  • Ball DJ, Slaughter CA, Hensley P, Garrard WT. Amino acid sequence of the N-terminal domain of calf thymus histone H2A.Z. FEBS Lett. 1983 Apr 5;154(1):166–170. [PubMed]
  • Carr AM, Dorrington SM, Hindley J, Phear GA, Aves SJ, Nurse P. Analysis of a histone H2A variant from fission yeast: evidence for a role in chromosome stability. Mol Gen Genet. 1994 Dec 1;245(5):628–635. [PubMed]
  • Childs G, Nocente-McGrath C, Lieber T, Holt C, Knowles JA. Sea urchin (lytechinus pictus) late-stage histone H3 and H4 genes: characterization and mapping of a clustered but nontandemly linked multigene family. Cell. 1982 Dec;31(2 Pt 1):383–393. [PubMed]
  • Dalton S, Robins AJ, Harvey RP, Wells JR. Transcription from the intron-containing chicken histone H2A.F gene is not S-phase regulated. Nucleic Acids Res. 1989 Feb 25;17(4):1745–1756. [PMC free article] [PubMed]
  • Doerder FP, Deak JC, Lief JH. Rate of phenotypic assortment in Tetrahymena thermophila. Dev Genet. 1992;13(2):126–132. [PubMed]
  • Ernst SG, Miller H, Brenner CA, Nocente-McGrath C, Francis S, McIsaac R. Characterization of a cDNA clone coding for a sea urchin histone H2A variant related to the H2A.F/Z histone protein in vertebrates. Nucleic Acids Res. 1987 Jun 11;15(11):4629–4644. [PMC free article] [PubMed]
  • Gaertig J, Gorovsky MA. Efficient mass transformation of Tetrahymena thermophila by electroporation of conjugants. Proc Natl Acad Sci U S A. 1992 Oct 1;89(19):9196–9200. [PMC free article] [PubMed]
  • Gaertig J, Gu L, Hai B, Gorovsky MA. High frequency vector-mediated transformation and gene replacement in Tetrahymena. Nucleic Acids Res. 1994 Dec 11;22(24):5391–5398. [PMC free article] [PubMed]
  • Gaertig J, Thatcher TH, Gu L, Gorovsky MA. Electroporation-mediated replacement of a positively and negatively selectable beta-tubulin gene in Tetrahymena thermophila. Proc Natl Acad Sci U S A. 1994 May 10;91(10):4549–4553. [PMC free article] [PubMed]
  • Gorovsky MA. Genome organization and reorganization in Tetrahymena. Annu Rev Genet. 1980;14:203–239. [PubMed]
  • Grunstein M. Nucleosomes: regulators of transcription. Trends Genet. 1990 Dec;6(12):395–400. [PubMed]
  • Grunstein M. Histone function in transcription. Annu Rev Cell Biol. 1990;6:643–678. [PubMed]
  • Harvey RP, Whiting JA, Coles LS, Krieg PA, Wells JR. H2A.F: an extremely variant histone H2A sequence expressed in the chicken embryo. Proc Natl Acad Sci U S A. 1983 May;80(10):2819–2823. [PMC free article] [PubMed]
  • Kahn RW, Andersen BH, Brunk CF. Transformation of Tetrahymena thermophila by microinjection of a foreign gene. Proc Natl Acad Sci U S A. 1993 Oct 15;90(20):9295–9299. [PMC free article] [PubMed]
  • Liu X, Bowen J, Gorovsky MA. Either of the major H2A genes but not an evolutionarily conserved H2A.F/Z variant of Tetrahymena thermophila can function as the sole H2A gene in the yeast Saccharomyces cerevisiae. Mol Cell Biol. 1996 Jun;16(6):2878–2887. [PMC free article] [PubMed]
  • Liu X, Gorovsky MA. Mapping the 5' and 3' ends of Tetrahymena thermophila mRNAs using RNA ligase mediated amplification of cDNA ends (RLM-RACE). Nucleic Acids Res. 1993 Oct 25;21(21):4954–4960. [PMC free article] [PubMed]
  • Norris D, Osley MA. The two gene pairs encoding H2A and H2B play different roles in the Saccharomyces cerevisiae life cycle. Mol Cell Biol. 1987 Oct;7(10):3473–3481. [PMC free article] [PubMed]
  • Stargell LA, Bowen J, Dadd CA, Dedon PC, Davis M, Cook RG, Allis CD, Gorovsky MA. Temporal and spatial association of histone H2A variant hv1 with transcriptionally competent chromatin during nuclear development in Tetrahymena thermophila. Genes Dev. 1993 Dec;7(12B):2641–2651. [PubMed]
  • Stoler S, Keith KC, Curnick KE, Fitzgerald-Hayes M. A mutation in CSE4, an essential gene encoding a novel chromatin-associated protein in yeast, causes chromosome nondisjunction and cell cycle arrest at mitosis. Genes Dev. 1995 Mar 1;9(5):573–586. [PubMed]
  • Sullivan KF, Hechenberger M, Masri K. Human CENP-A contains a histone H3 related histone fold domain that is required for targeting to the centromere. J Cell Biol. 1994 Nov;127(3):581–592. [PMC free article] [PubMed]
  • Thatcher TH, Gorovsky MA. Phylogenetic analysis of the core histones H2A, H2B, H3, and H4. Nucleic Acids Res. 1994 Jan 25;22(2):174–179. [PMC free article] [PubMed]
  • van Daal A, Elgin SC. A histone variant, H2AvD, is essential in Drosophila melanogaster. Mol Biol Cell. 1992 Jun;3(6):593–602. [PMC free article] [PubMed]
  • van Daal A, White EM, Elgin SC, Gorovsky MA. Conservation of intron position indicates separation of major and variant H2As is an early event in the evolution of eukaryotes. J Mol Evol. 1990 May;30(5):449–455. [PubMed]
  • van Daal A, White EM, Gorovsky MA, Elgin SC. Drosophila has a single copy of the gene encoding a highly conserved histone H2A variant of the H2A.F/Z type. Nucleic Acids Res. 1988 Aug 11;16(15):7487–7497. [PMC free article] [PubMed]
  • White EM, Shapiro DL, Allis CD, Gorovsky MA. Sequence and properties of the message encoding Tetrahymena hv1, a highly evolutionarily conserved histone H2A variant that is associated with active genes. Nucleic Acids Res. 1988 Jan 11;16(1):179–198. [PMC free article] [PubMed]
  • Wolffe AP, Pruss D. Deviant nucleosomes: the functional specialization of chromatin. Trends Genet. 1996 Feb;12(2):58–62. [PubMed]
  • Wu RS, Panusz HT, Hatch CL, Bonner WM. Histones and their modifications. CRC Crit Rev Biochem. 1986;20(2):201–263. [PubMed]

Articles from Molecular and Cellular Biology are provided here courtesy of American Society for Microbiology (ASM)

Formats:

Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...

Links

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...