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Telomeric heterochromatin in Plasmodium falciparum.

Hernandez-Rivas R, Pérez-Toledo K, Herrera Solorio AM, Delgadillo DM, Vargas M - J. Biomed. Biotechnol. (2010)

Bottom Line: Telomeres and subtelomeric regions are enriched in epigenetic marks that are specific to heterochromatin, such as methylation of lysine 9 of histone H3 and lysine 20 of histone H4.In P. falciparum, histone modifications and the presence of both the heterochromatin "writing" (PfSir2, PKMT) and "reading" (PfHP1) machinery at telomeric and subtelomeric regions indicate that these regions are likely to have heterochromatic structure that is epigenetically regulated.This structure may be important for telomere functions such as the silencing of the var gene family implicated in the cytoadherence and antigenic variation of these parasites.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, 07360 México, DF, Mexico. rohernan@cinvestav.mx

ABSTRACT
Until very recently, little was known about the chromatin structure of the telomeres and subtelomeric regions in Plasmodium falciparum. In yeast and Drosophila melanogaster, chromatin structure has long been known to be an important aspect in the regulation and functioning of these regions. Telomeres and subtelomeric regions are enriched in epigenetic marks that are specific to heterochromatin, such as methylation of lysine 9 of histone H3 and lysine 20 of histone H4. In P. falciparum, histone modifications and the presence of both the heterochromatin "writing" (PfSir2, PKMT) and "reading" (PfHP1) machinery at telomeric and subtelomeric regions indicate that these regions are likely to have heterochromatic structure that is epigenetically regulated. This structure may be important for telomere functions such as the silencing of the var gene family implicated in the cytoadherence and antigenic variation of these parasites.

Show MeSH
Hetrochromatin in S. cerevisiae, S. pombe, P. falciparum and human.
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Related In: Results  -  Collection


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fig2: Hetrochromatin in S. cerevisiae, S. pombe, P. falciparum and human.

Mentions: Differences in telomere length may be due to differences in the organization of chromatin in these regions. Micrococcal nuclease assays have established that the innermost part of telomeres in Saccharomyces cerevisiae and Schizosaccharomyces pombe have a nucleosomal organization that consists of three or four nucleosomes (Figure 2). The outermost part of the telomeres, known as the telosome, is not associated with nucleosomes [43]. Instead, this portion of the chromosome is bound by a large number of telomere-specific proteins that form the telosome complex. In S. cerevisiae, for example, multiprotein complexes such as Rap1, the Ku complex, Taz1, Rif 1, the Mlp complex, telomerase and the SIR silencing complex comprised of the proteins Sir2, Sir3 and Sir4 [44, 45] have been isolated and characterized. Telomeres in P. falciparum have an organization similar to that of the telomeres in S. cerevisiae, with an internal region associated with three to four nucleosomes and an outer region free of them [13]. Several proteins orthologous to those in the yeast telosome complexes, such as PfSir2 [21], PfOrc1 [46] and telomerase (PfTERT) [47], have also been found in this parasite. All these findings support the existence of a telosome complex in P. falciparum (Figure 2).


Telomeric heterochromatin in Plasmodium falciparum.

Hernandez-Rivas R, Pérez-Toledo K, Herrera Solorio AM, Delgadillo DM, Vargas M - J. Biomed. Biotechnol. (2010)

Hetrochromatin in S. cerevisiae, S. pombe, P. falciparum and human.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2821646&req=5

fig2: Hetrochromatin in S. cerevisiae, S. pombe, P. falciparum and human.
Mentions: Differences in telomere length may be due to differences in the organization of chromatin in these regions. Micrococcal nuclease assays have established that the innermost part of telomeres in Saccharomyces cerevisiae and Schizosaccharomyces pombe have a nucleosomal organization that consists of three or four nucleosomes (Figure 2). The outermost part of the telomeres, known as the telosome, is not associated with nucleosomes [43]. Instead, this portion of the chromosome is bound by a large number of telomere-specific proteins that form the telosome complex. In S. cerevisiae, for example, multiprotein complexes such as Rap1, the Ku complex, Taz1, Rif 1, the Mlp complex, telomerase and the SIR silencing complex comprised of the proteins Sir2, Sir3 and Sir4 [44, 45] have been isolated and characterized. Telomeres in P. falciparum have an organization similar to that of the telomeres in S. cerevisiae, with an internal region associated with three to four nucleosomes and an outer region free of them [13]. Several proteins orthologous to those in the yeast telosome complexes, such as PfSir2 [21], PfOrc1 [46] and telomerase (PfTERT) [47], have also been found in this parasite. All these findings support the existence of a telosome complex in P. falciparum (Figure 2).

Bottom Line: Telomeres and subtelomeric regions are enriched in epigenetic marks that are specific to heterochromatin, such as methylation of lysine 9 of histone H3 and lysine 20 of histone H4.In P. falciparum, histone modifications and the presence of both the heterochromatin "writing" (PfSir2, PKMT) and "reading" (PfHP1) machinery at telomeric and subtelomeric regions indicate that these regions are likely to have heterochromatic structure that is epigenetically regulated.This structure may be important for telomere functions such as the silencing of the var gene family implicated in the cytoadherence and antigenic variation of these parasites.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, 07360 México, DF, Mexico. rohernan@cinvestav.mx

ABSTRACT
Until very recently, little was known about the chromatin structure of the telomeres and subtelomeric regions in Plasmodium falciparum. In yeast and Drosophila melanogaster, chromatin structure has long been known to be an important aspect in the regulation and functioning of these regions. Telomeres and subtelomeric regions are enriched in epigenetic marks that are specific to heterochromatin, such as methylation of lysine 9 of histone H3 and lysine 20 of histone H4. In P. falciparum, histone modifications and the presence of both the heterochromatin "writing" (PfSir2, PKMT) and "reading" (PfHP1) machinery at telomeric and subtelomeric regions indicate that these regions are likely to have heterochromatic structure that is epigenetically regulated. This structure may be important for telomere functions such as the silencing of the var gene family implicated in the cytoadherence and antigenic variation of these parasites.

Show MeSH