Histones and Chromatin Structure in Tetrahymena Macro- and Micronuclei

Gorovsky, Martin A.; Glover, Claiborne V.C.; Johmann, Carol A.; Keevert, Josephine Bowen; Mathis, Diane; Samuelson, Megan I.

doi:10.1101/sqb.1978.042.01.052

Cited by 63 publications

(45 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…S4), agreeing well with previous estimates obtained from gel analysis of MNase-treated macronuclear chromatin (Supplemental Fig. S2A; Gorovsky et al 1978). The average nucleosome linker length remained constant in both log-phase and starved nutritional conditions, consistent with previous studies showing that this property remains largely invariant between diverse developmental and nutritional states (Zhang et al 2011a).…”

Section: Genome-wide Nucleosome Maps Of the Tetrahymena Thermophila Msupporting

confidence: 81%

DNA-guided establishment of nucleosome patterns within coding regions of a eukaryotic genome

et al. 2015

View full text Add to dashboard Cite

A conserved hallmark of eukaryotic chromatin architecture is the distinctive array of well-positioned nucleosomes downstream from transcription start sites (TSS). Recent studies indicate that trans-acting factors establish this stereotypical array. Here, we present the first genome-wide in vitro and in vivo nucleosome maps for the ciliate Tetrahymena thermophila. In contrast with previous studies in yeast, we find that the stereotypical nucleosome array is preserved in the in vitro reconstituted map, which is governed only by the DNA sequence preferences of nucleosomes. Remarkably, this average in vitro pattern arises from the presence of subsets of nucleosomes, rather than the whole array, in individual Tetrahymena genes. Variation in GC content contributes to the positioning of these sequence-directed nucleosomes and affects codon usage and amino acid composition in genes. Given that the AT-rich Tetrahymena genome is intrinsically unfavorable for nucleosome formation, we propose that these “seed” nucleosomes—together with trans-acting factors—may facilitate the establishment of nucleosome arrays within genes in vivo, while minimizing changes to the underlying coding sequences.

show abstract

Section: Genome-wide Nucleosome Maps Of the Tetrahymena Thermophila Msupporting

confidence: 81%

DNA-guided establishment of nucleosome patterns within coding regions of a eukaryotic genome

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Micro-and macronuclear chromatin of Tetrahymena have very different average internucleosomal repeat lengths of 175 and 202 bp, respectively (26). Prior to this study, that difference might have been ascribed to the very different structures of the micronuclear and macronuclear linker histones (13,14,30).…”

Section: Discussionmentioning

confidence: 99%

Nucleosome Positioning Is Independent of Histone H1in Vivo

Karrer

VanNuland²

1999

Journal of Biological Chemistry

View full text Add to dashboard Cite

“…This is slightly more than would be required for methylation of the entire genome once per nucleosome, since the internucleosomal distance has been estimated to be about 200 base pairs by both nuclease digestion and cross-linking experiments (15,20,22). It would be of interest to know whether methylated adenines are evenly distributed in the Tetrahymena genome.…”

Section: Discussionmentioning

confidence: 99%

Site-specific methylation of adenine in the nuclear genome of a eucaryote, Tetrahymena thermophila.

Harrison¹,

Findly²,

Karrer³

1986

Mol. Cell. Biol.

View full text Add to dashboard Cite

DNA in the polyploid macronucleus of the ciliated protozoan Tetrahymena thermophila contains the modified base N6-methyladenine. We identified two GATC sites which are methylated in most or all of the 45 copies of the macronuclear genome. One site is 2 kilobases 5' to the histone H4-I gene, and the other is 5 kilobases 3' to the 73-kilodalton heat shock protein gene. These sites are de novo methylated between 10 and 16 h after initiation of conjugation, during macronuclear anlage development. The methylation states of these two GATC sites and four other unmethylated GATC sites do not change in the DNA of cells cultured under conditions which change the activity of the genes, including logarithmic growth, starvation, and heat shock.The nuclear DNAs of most eucaryotes contain the modified base 5-methylcytosine (5MeC) as a minor component. In many cases, site-specific methylation of cytosine, particularly near the 5' ends of genes, has been correlated with gene inactivity (for reviews see references 1, 17, and 45). Therefore, it has been suggested that 5MeC may be involved in transcriptional regulation.N6-methyladenine (N6MeA) is found in the nuclear DNAs of several unicellular eucaryotes, either in combination with other modifications or as the only modified base. The DNAs of the green algae Chlamydomonas reinhardi and Chlorella spp. have both methylcytosine and methyladenine (28, 46), while only methylcytosine has been found in the DNA of another green alga, Euglena gracilis (40). In the ciliates Tetrahymena (23), Paramecium (16), Oxytricha (39), and Stylonychia (5) N6MeA is the sole modified base. The function of N6MeA in eucaryotic DNA is unknown.We examined methylation at specific sites in the genome of Tetrahymena thermophila. Tetrahymena cells contain two nuclei, a diploid micronucleus and a polyploid macronucleus. The macronucleus is responsible for most, if not all, transcriptional activity during vegetative growth. During sexual reproduction (conjugation), the macronucleus is destroyed, and mitotic products of the zygotic micronucleus develop into a new micronucleus and a new macronucleus. The developing macronucleus, called the anlage, undergoes many structural and morphological changes, including DNA replication to a final DNA content of 45c (49), elimination and rearrangement of germ line DNA sequences (50), and de novo methylation (9, 26).Although the micronuclear DNA of Tetrahymena cells does not contain modified bases, 0.8% of the adenine residues in the transcriptionally active macronucleus are modified to N6MeA (23,28). A partially purified methylase activity was isolated from macronuclei (10). A nearestneighbor analysis of in vivo methylated DNA showed that all four bases are found 5' to the methylated adenine, but only thymidine is found 3'. Some of the methyladenine residues in Tetrahymena macronuclear DNA occur in the sequence * Corresponding author. t Present address: Eleanor Roosevelt Cancer Institute, Denver, CO 80262.5'-GMeATC-3' and can be assayed by digestion with restriction enzyme DpnI...

show abstract

Histones and Chromatin Structure in Tetrahymena Macro- and Micronuclei

Cited by 63 publications

References 0 publications

DNA-guided establishment of nucleosome patterns within coding regions of a eukaryotic genome

DNA-guided establishment of nucleosome patterns within coding regions of a eukaryotic genome

Nucleosome Positioning Is Independent of Histone H1in Vivo

Site-specific methylation of adenine in the nuclear genome of a eucaryote, Tetrahymena thermophila.

Contact Info

Product

Resources

About