DNA of Drosophila melanogaster contains 5-methylcytosine

Abstract

820 Sequence-specific nuclear matrix proteins share rod-domain with intermediate filaments. A.R. Goloudina, A.P. Voronin, A.S. Kukalev, N.I. Enukashvily 194064, Russia, St.Petersburg, Tichoretskii av.4 Lamins, which are the major and well-investigated components of the nuclear matrix (NM), belong to the 5-th class of the wide family of the intermediate filament composing proteins. Lamins are a component of the inner NM as well as the NM outer partlamina. Nature of the main fibrillar component of the NM remains obscure constant attempts notwithstanding. From its morphological appearance the main NM proteins belong to the group of intermediate filaments; still all the antibodies (AB) against different proteins from this group stain only part of the filaments or filaments fragments. Lamins DNA binding properties are unquestionable but the sequence-specificity is not distinct. Mouse Membrane-associated Telomere Binding Protein (mMTBP) was found in NM preparations with the AB against MTBP and high affinity binding to (T2AG3)135 vertebrate telomere fragment TRF2/mMTBP localised near NE and bind telomers which are to be in contact with NE. TRF2/mMTBP possesses rod-domain of intermediate filaments proteins according to the reactivity with the correspondent AB and computer analysis of the TFRZ sequence published. Interaction between NM and pericentromeric alpha satellite DNA (alfa-DNA) caused by NM proteins specific in binding. The results of 2-D electrophoresis of DNA-protein complexes formed by aDNA from the chromosome 21 centromeric region ( without CENP-B box) and NM proteins, hyper-shift assay and immunoblotting showed that these complexes include proteins with Mr approx. 80 and 70 kD which are neither CENP-B nor lamins A/C and B. The major protein of the complex of 70 kD is not cloned yet but also contains rod-domain according to the reactivity with the correspondent AB So at least several NM proteins with more or less determined sequencebinding specificity share rod-domain but have different DNA-binding domains.

Genome methylation in D. melanogaster is found at specific short motifs and is independent of DNMT2 activity

“…Although we find that methylation can be present on a substantial proportion of alleles within methylated regions, methylation is virtually never present on more than half of the alleles. Thus, although methylated regions make up ;1% of the Drosophila genome, the proportion of methylated cytosines at stage 5 is much less than this, consistent with previous estimates derived from studies of bulk methylation (Gowher et al 2000;Lyko et al 2000a;Marhold et al 2004).…”

“…Drosophila was long thought to lack cytosine methylation, but identification of a Drosophila homolog of DNA methyltransferase 2 (MT2, also known as DNMT2) (Hung et al 1999;Lyko et al 2000b) prompted studies that established the presence of small amounts of genomic cytosine methylation in early embryogenesis (Gowher et al 2000;Lyko et al 2000a;Kunert et al 2003). Despite this, the pattern and function of cytosine methylation in Drosophila has never been clear, and recently considerable doubt has been expressed as to the presence of any significant quantity of genomic methylation (Goll et al 2006;Schaefer and Lyko 2010a;Zemach et al 2010;Raddatz et al 2013).…”

Expression of murine DNA methyltransferases Dnmt1 and Dnmt3a in the yeast Saccharomyces cerevisiae

“…Somewhat different conclusions can be drawn from a set of similar analyses performed in D. melanogaster (Lyko et al, 1999), another model eukaryote until recently believed not to methylate its DNA (see discussion in Gowher et al, 2000). Murine DNA methyltransferase Dnmt1 expressed in D. melanogaster, although active in vitro, could not methylate the fly's DNA in vivo, although it is difficult to tell from the published data that a level of methylation as low as the 0.06% observed in our work would be detected.…”

“…In fact, Drosophila do methylate their DNA, although mainly during larval development and only at a very low level (Gowher et al, 2000;Lyko et al, 2000;Salzberg et al, 2004). Nevertheless, their cells have all the components necessary for tightly regulated DNA methylation.…”

Epigenetics: heterochromatin meets RNAi

“…Methylation of cytosine residues of the DNA is a common feature of silenced genes in heterochromatin in many eukaryotes. However, DNA methylation has not been found in the common model organisms, the yeasts S. cerevisiae and S. pombe or the nematode Caenorhabditis elegans, and only low levels are detected in the fruit fly D. melanogaster [18] (Table 1). De novo DNA methylation of cytosines can be targeted by methylation of H3K9 or by homologous RNA [19].…”