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Bjerling, Pernilla
Publications (5 of 5) Show all publications
Walfridsson, J., Bjerling, P., Thalen, M., Yoo, E.-J., Park, S. D. & Ekwall, K. (2005). The CHD remodeling factor Hrp1 stimulates CENP-A loading to centromeres. Nucleic Acids Research, 33(9), 2868-2879
Open this publication in new window or tab >>The CHD remodeling factor Hrp1 stimulates CENP-A loading to centromeres
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2005 (English)In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 33, no 9, p. 2868-2879Article in journal (Refereed) Published
Abstract [en]

Centromeres of fission yeast are arranged with a central core DNA sequence flanked by repeated sequences. The centromere-associated histone H3 variant Cnp1 ( SpCENP-A) binds exclusively to central core DNA, while the heterochromatin proteins and cohesins bind the surrounding outer repeats. CHD (chromo-helicase/ ATPase DNA binding) chromatin remodeling factors were recently shown to affect chromatin assembly in vitro. Here, we report that the CHD protein Hrp1 plays a key role at fission yeast centromeres. The hrp1&UDelta; mutant disrupts silencing of the outer repeats and central core regions of the centromere and displays chromosome segregation defects characteristic for dysfunction of both regions. Importantly, Hrp1 is required to maintain high levels of Cnp1 and low levels of histone H3 and H4 acetylation at the central core region. Hrp1 interacts directly with the centromere in early S-phase when centromeres are replicated, suggesting that Hrp1 plays a direct role in chromatin assembly during DNA replication.

National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:sh:diva-14398 (URN)10.1093/nar/gki579 (DOI)000229544600019 ()15908586 (PubMedID)2-s2.0-20144376151 (Scopus ID)
Available from: 2011-12-21 Created: 2011-12-21 Last updated: 2017-07-19Bibliographically approved
Bjerling, P., Ekwall, K., Egel, R. & Thon, G. (2004). A novel type of silencing factor, Clr2, is necessary for transcriptional silencing at various chromosomal locations in the fission yeast Schizosaccharomyces pombe. Nucleic Acids Research, 32(15), 4421-4428
Open this publication in new window or tab >>A novel type of silencing factor, Clr2, is necessary for transcriptional silencing at various chromosomal locations in the fission yeast Schizosaccharomyces pombe
2004 (English)In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 32, no 15, p. 4421-4428Article in journal (Refereed) Published
Abstract [en]

The mating-type region of the fission yeast Schizosaccharomyces pombe comprises three loci: mat1, mat2-P and mat3-M. mat1 is expressed and determines the mating type of the cell. mat2-P and mat3-M are two storage cassettes located in a 17 kb heterochromatic region with features identical to those of mammalian heterochromatin. Mutations in the swi6(+), clr1(+), clr2(+), clr3(+), clr4(+) and clr6(+) genes were obtained in screens for factors necessary for silencing the mat2-P-mat3-M region. swi6(+) encodes a chromodomain protein, clr3(+) and clr6(+) histone deacetylases, and clr4(+) a histone methyltransferase. Here, we describe the cloning and characterization of clr2(+). The clr2(+) gene encodes a 62 kDa protein with no obvious sequence homologs. Deletion of clr2(+) not only affects transcriptional repression in the mating-type region, but also centromeric silencing and silencing of a PolII-transcribed gene inserted in the rDNA repeats. Using chromatin immunoprecipitation, we show that Clr2 is necessary for histone hypoacetylation in the mating-type region, suggesting that Clr2 acts upstream of histone deacetylases to promote transcriptional silencing.

National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:sh:diva-15504 (URN)10.1093/nar/gkh780 (DOI)000223947100001 ()15317867 (PubMedID)2-s2.0-4243144074 (Scopus ID)
Available from: 2012-02-20 Created: 2012-02-20 Last updated: 2017-07-19Bibliographically approved
Bjerling, P. & Ekwall, K. (2002). Centromere domain organization and histone modifications. Brazilian journal of medical and biological research, 35(5), 499-507
Open this publication in new window or tab >>Centromere domain organization and histone modifications
2002 (English)In: Brazilian journal of medical and biological research, ISSN 0100-879X, E-ISSN 1414-431X, Vol. 35, no 5, p. 499-507Article in journal (Refereed) Published
Abstract [en]

Centromere function requires the proper coordination of several subfunctions, such as kinetochore assembly, sister chromatid cohesion, binding of kinetochore microtubules, orientation of sister kinetochores to opposite spindle poles, and their movement towards the spindle poles. Centromere structure appears to be organized in different, separable domains in order to accomplish these functions. Despite the conserved nature of centromere functions, the molecular genetic definition of the DNA sequences that form a centromere in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe, in the fruit fly Drosophila melanogaster, and in humans has revealed little conservation at the level of centromere DNA sequences. Also at the protein level few centromere proteins are conserved in all of these four organisms and many are unique to the different organisms. The recent analysis of the centromere structure in the yeast S. pombe by electron microscopy and detailed immunofluorescence microscopy of Drosophila centromeres have brought to light striking similarities at the overall structural level between these centromeres and the human centromere. The structural organization of the centromere is generally multilayered with a heterochromaun domain and a central core/inner plate region, which harbors the outer plate structures of the kinetochore. It is becoming increasingly clear that the key factors for assembly and function of the centromere structure are the specialized histories and modified histones which are present in the centromeric heterochromatin and in the chromatin of the central core. Thus, despite the differences in the DNA sequences and the proteins that define a centromere, there is an overall structural similarity between centromeres in evolutionarily diverse eukaryotes.

National Category
Biological Sciences
Identifiers
urn:nbn:se:sh:diva-15805 (URN)10.1590/S0100-879X2002000500001 (DOI)000175800900001 ()12011934 (PubMedID)2-s2.0-0036259748 (Scopus ID)
Available from: 2012-03-08 Created: 2012-03-07 Last updated: 2017-12-07Bibliographically approved
Thon, G., Bjerling, P., Bunner, C. M. & Verhein-Hansen, J. (2002). Expression-state boundaries in the mating-type region of fission yeast. Genetics, 161(2), 611-622
Open this publication in new window or tab >>Expression-state boundaries in the mating-type region of fission yeast
2002 (English)In: Genetics, ISSN 0016-6731, E-ISSN 1943-2631, Vol. 161, no 2, p. 611-622Article in journal (Refereed) Published
Abstract [en]

A transcriptionally silent chromosomal domain is found in the mating-type region of fission yeast. Here we show that this domain is delimited by 2-kb inverted repeats, IR-I, and IR-R, IR-I, and IR-R prevent the expansion of transcription-permissive chromatin into the silenced region and that of silenced chromatin into the expressed region. Their insulator activity is partially orientation dependent. The silencing defects that follow deletion or inversion of IR-R are suppressed by high dosage of the chromodomain protein Swi6. Combining chromosomal deletions and Swi6 overexpression shows that IR-I, and IR-R provide firm borders in a region where competition between silencing and transcriptional competence occurs. IR-R possesses autonomously replicating sequence (ARS) activity, leading to a model where replication factors, or replication itself, participate in boundary formation.

National Category
Genetics
Identifiers
urn:nbn:se:sh:diva-15804 (URN)000176374600012 ()12072458 (PubMedID)2-s2.0-0035989380 (Scopus ID)
Available from: 2012-03-08 Created: 2012-03-07 Last updated: 2017-07-20Bibliographically approved
Bjerling, P., Silverstein, R. A., Thon, G., Caudy, A., Grewal, S. & Ekwall, K. (2002). Functional divergence between histone deacetylases in fission yeast by distinct cellular localization and in vivo specificity. Molecular and Cellular Biology, 22(7), 2170-2181
Open this publication in new window or tab >>Functional divergence between histone deacetylases in fission yeast by distinct cellular localization and in vivo specificity
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2002 (English)In: Molecular and Cellular Biology, ISSN 0270-7306, E-ISSN 1098-5549, Vol. 22, no 7, p. 2170-2181Article in journal (Refereed) Published
Abstract [en]

Histone deacetylases (HDACs) are important for gene regulation and the maintenance of heterochromatin in eukaryotes. Schizosaccharomyces pombe was used as a model system to investigate the functional divergence within this conserved enzyme family. S. pombe has three HDACs encoded by the hda1(+), clr(3+), and clr6(+) genes. Strains mutated in these genes have previously been shown to display strikingly different phenotypes when assayed for viability, chromosome loss, and silencing. Here, conserved differences in the substrate binding pocket identify Clr6 and Hda1 as class I HDACs, while Clr3 belongs in the class II family. Furthermore, these HDACs were shown to have strikingly different subcellular localization patterns. Hda1 was localized to the cytoplasm, while most of Clr3 resided throughout the nucleus. Finally, Clr6 was localized exclusively on the chromosomes in a spotted pattern. Interestingly, Clr3, the only HDAC present in the nucleolus, was required for ribosomal DNA (rDNA) silencing. Clr3 presumably acts directly on heterochromatin, since it colocalized with the centromere, mating-type region, and rDNA as visualized by in situ hybridization. In addition, Clr3 could be cross-linked to mat3 in chromatin immunoprecipitation experiments. Western analysis of bulk histone preparations indicated that Hda1 (class I) had a generally low level of activity in vivo and Clr6 (class 1) had a high level of activity and broad in vivo substrate specificity, whereas Clr3 (class II) displayed its main activity on acetylated lysine 14 of histone H3. Thus, the distinct functions of the S. pombe HDACs are likely explained by their distinct cellular localization and their different in vivo specificities.

National Category
Biological Sciences
Identifiers
urn:nbn:se:sh:diva-15808 (URN)10.1128/MCB.22.7.2170-2181.2002 (DOI)000174407500020 ()11884604 (PubMedID)2-s2.0-0036122494 (Scopus ID)
Available from: 2012-03-08 Created: 2012-03-07 Last updated: 2017-07-20Bibliographically approved
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