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Zhu N, Hansen U. Transcriptional regulation by HMGN proteins. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2010; 1799:74-9. [PMID: 20123070 DOI: 10.1016/j.bbagrm.2009.11.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 10/25/2009] [Accepted: 11/03/2009] [Indexed: 12/20/2022]
Abstract
High mobility group nucleosomal proteins (HMGNs) are small non-histone proteins associated with chromatin. HMGNs have the unique ability to bind to nucleosomes with higher affinity than to naked DNA [1]. They have been studied extensively for their ability to modulate transcription. Although initially viewed as general transcriptional activators on chromatin templates, it is now appreciated that they are instead highly specific modulators of gene expression. We review the mechanisms for targeting HMGNs to specific genes and for how they subsequently regulate transcription.
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Affiliation(s)
- Nan Zhu
- Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA
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2
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Rattner BP, Yusufzai T, Kadonaga JT. HMGN proteins act in opposition to ATP-dependent chromatin remodeling factors to restrict nucleosome mobility. Mol Cell 2009; 34:620-6. [PMID: 19524541 DOI: 10.1016/j.molcel.2009.04.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 04/03/2009] [Accepted: 04/10/2009] [Indexed: 12/20/2022]
Abstract
The high-mobility group N (HMGN) proteins are abundant nonhistone chromosomal proteins that bind specifically to nucleosomes at two high-affinity sites. Here we report that purified recombinant human HMGN1 (HMG14) and HMGN2 (HMG17) potently repress ATP-dependent chromatin remodeling by four different molecular motor proteins. In contrast, mutant HMGN proteins with double Ser-to-Glu mutations in their nucleosome-binding domains are unable to inhibit chromatin remodeling. The HMGN-mediated repression of chromatin remodeling is reversible and dynamic. With the ACF chromatin remodeling factor, HMGN2 does not directly inhibit the ATPase activity but rather appears to reduce the affinity of the factor to chromatin. These findings suggest that HMGN proteins serve as a counterbalance to the action of the many ATP-dependent chromatin remodeling activities in the nucleus.
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Affiliation(s)
- Barbara P Rattner
- Section of Molecular Biology, University of California, San Diego, La Jolla, CA 92093-0347, USA
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3
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The role of HMGN proteins in chromatin function. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/s0167-7306(03)39006-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Abstract
The high mobility group N (HMGN) proteins are a family of nuclear proteins that binds to nucleosomes, changes the architecture of chromatin, and enhances transcription and replication from chromatin templates. The intracellular organization of the HMGN (previously known as HMG-14/17) proteins is dynamic and is related to both cell-cycle and transcriptional events. These proteins roam the nucleus, perhaps as part of multiprotein complexes, and their target interactions are modulated by posttranslational modifications. Functional studies on HMGN proteins provide insights into the molecular mechanisms by which structural proteins affect DNA-dependent activities in the context of chromatin.
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Affiliation(s)
- M Bustin
- Protein Section, Laboratory of Metabolism, Division of Basic Sciences, National Cancer Institute, National Institutes of Health, 20892, Bethesda, MD, USA.
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5
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Bustin M. Regulation of DNA-dependent activities by the functional motifs of the high-mobility-group chromosomal proteins. Mol Cell Biol 1999; 19:5237-46. [PMID: 10409715 PMCID: PMC84367 DOI: 10.1128/mcb.19.8.5237] [Citation(s) in RCA: 653] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- M Bustin
- Protein Section, Laboratory of Molecular Carcinogenesis, Division of Basic Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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6
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Postnikov YV, Bustin M. Reconstitution of high mobility group 14/17 proteins into nucleosomes and chromatin. Methods Enzymol 1999; 304:133-55. [PMID: 10372359 DOI: 10.1016/s0076-6879(99)04010-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Affiliation(s)
- Y V Postnikov
- Protein Section, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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Postnikov YV, Herrera JE, Hock R, Scheer U, Bustin M. Clusters of nucleosomes containing chromosomal protein HMG-17 in chromatin. J Mol Biol 1997; 274:454-65. [PMID: 9417927 DOI: 10.1006/jmbi.1997.1391] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Chromosomal proteins HMG-14 and HMG-17 are nucleosome binding proteins which can function as architectural elements to alter the structure of the chromatin fiber and enhance transcription from chromatin templates. Here we study the spatial organization of these HMG proteins in the nucleus and the distribution of nucleosomes containing HMG-17 in the chromatin fiber. By confocal immunofluorescence microscopy we find that HMG-14/17 proteins are clustered into foci containing either HMG-14 or HMG-17. These results suggest that HMG-14/17 proteins segregate into distinct nuclear domains. Indeed, immunofractionation of defined length oligonucleosomes, with affinity pure antibodies to HMG-17, indicates that oligonucleosomes containing HMG-17 are devoid of HMG-14. Quantitative analysis indicates that in cellular chromatin nucleosomes containing HMG-17 are clustered. The average size of the cluster is six contiguous HMG-17-containing nucleosomes. The nucleosomes in this cluster contain either two or zero molecules of HMG-17 and a complete set of four core histones. We suggest that HMG-14/17 proteins modify the nucleosomal organization of the 30 nm chromatin fiber, to unfold the higher order chromatin structure and facilitate access to the underlying DNA sequence. Clustering of architectural elements, such as HMG proteins and linker histone subtypes into distinct domains, may lead to structural and functional heterogeneity along the chromatin fiber.
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Affiliation(s)
- Y V Postnikov
- Protein Section, LMC, DBS, NCI, NIH, Bethesda, MD 20892, USA
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Bustin M, Reeves R. High-mobility-group chromosomal proteins: architectural components that facilitate chromatin function. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1996; 54:35-100. [PMID: 8768072 DOI: 10.1016/s0079-6603(08)60360-8] [Citation(s) in RCA: 568] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- M Bustin
- Laboratory of Molecular Carcinogenesis, National Cancer Institute, National Institute of Health, Bethesda, Maryland 20892, USA
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9
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Paranjape SM, Krumm A, Kadonaga JT. HMG17 is a chromatin-specific transcriptional coactivator that increases the efficiency of transcription initiation. Genes Dev 1995; 9:1978-91. [PMID: 7649479 DOI: 10.1101/gad.9.16.1978] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We have examined the effect of HMG17 on transcription by RNA polymerase II by the assembly and analysis of HMG17-containing chromatin templates consisting of regularly spaced nucleosomal arrays. Structural analysis of the chromatin indicated that HMG17 is incorporated into chromatin in a physiological manner with the full complement of core histones. The transcriptional studies revealed that HMG17 stimulates transcription in conjunction with the sequence-specific activator GAL4-VP16. This effect was observed with chromatin, but not with non-nucleosomal templates, and required the presence of HMG17 during chromatin assembly. The incorporation of HMG17 into chromatin resulted in a 7- to 40-fold stimulation of GAL4-VP16-activated transcription to levels that were comparable to those observed with histone-free DNA templates. In contrast, transcription from HMG17-containing chromatin was not detectable in the absence of GAL4-VP16 or with a GAL4 derivative [GAL4(1-147)] lacking the VP16 activation domain. Finally, the incorporation of HMG17 into chromatin was found to increase the efficiency of transcription initiation, but not the extent of transcriptional elongation. Thus, HMG17 is a chromatin-specific transcriptional coactivator that increases the efficiency of initiation of transcription by RNA polymerase II.
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Affiliation(s)
- S M Paranjape
- Department of Biology, University of California, San Diego, La Jolla 92093-0347, USA
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Postnikov YV, Lehn DA, Robinson RC, Friedman FK, Shiloach J, Bustin M. The cooperative binding of chromosomal protein HMG-14 to nucleosome cores is reduced by single point mutations in the nucleosomal binding domain. Nucleic Acids Res 1994; 22:4520-6. [PMID: 7971283 PMCID: PMC308488 DOI: 10.1093/nar/22.21.4520] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Mutants of human chromosomal protein HMG-14 were generated by site directed mutagenesis and used to study functional domains in this protein. A replacement of serine by cysteine at position 7 did not affect the binding of the protein to nucleosome cores. The sulfhydryl group in the nucleosome-bound protein is accessible to modifying agents suggesting that position 7 in the protein is not in close contact with either the DNA or the histones in the core particles. Under cooperative binding conditions, replacements of alanine by proline at position 21, or of lysine by cysteine at position 26, decreased the affinity of the protein for nucleosome cores 6.7- and 3-fold respectively. In contrast, the non-cooperative mode of binding was only minimally affected. A replacement of glutamic acid by glutamine at position 76 caused only minor changes in the binding of the protein to the cores. The results indicate that single point mutations, which change either the conformation or change in the nucleosomal binding domain of the protein, significantly reduce the ability of the HMG-14 protein to bind to nucleosome cores. We suggest that in chromatin the protein binds to nucleosomes in a cooperative manner and that upon binding to nucleosomes the protein acquires a distinct conformation.
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Affiliation(s)
- Y V Postnikov
- Laboratory of Molecular Carcinogenesis, NCI, National Institutes of Health, Bethesda, MD 20892
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11
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Aberrant expression of high mobility group chromosomal protein 14 affects cellular differentiation. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)38695-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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12
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Postnikov YV, Shick VV, Belyavsky AV, Khrapko KR, Brodolin KL, Nikolskaya TA, Mirzabekov AD. Distribution of high mobility group proteins 1/2, E and 14/17 and linker histones H1 and H5 on transcribed and non-transcribed regions of chicken erythrocyte chromatin. Nucleic Acids Res 1991; 19:717-25. [PMID: 2017359 PMCID: PMC333702 DOI: 10.1093/nar/19.4.717] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Quantitative analysis of distribution of chromosomal proteins on single copy DNA sequences has been further developed. Our approach consists of DNA-protein crosslinking within whole cells or isolated nuclei, specific immunoaffinity isolation of crosslinked complexes via protein and identification of crosslinked DNA by hybridisation with single-stranded DNA probes. The present study shows that transcribed chromatin of chicken embryonic erythrocyte beta globin gene is characterized by about 1.5-2.5-fold higher density of HMG 14/17 and 2-fold lower density of H1 and H5 as compared with non-transcribed chromatin of ovalbumin and lysozyme genes, whereas HMG 1/2, E proteins were equally distributed between DNA of both transcribed and non-transcribed genes. The depletion of H1/H5 in beta globin sequences was verified by the 'protein image' hybridisation technique (1). The DNase I hypersensitive site located 5' upstream from beta globin gene is deficient in all the proteins assayed, what implies a drastic disruption in the nucleosomal array. Minor quantitative changes of protein pattern suggest transient local perturbation of the chromatin on transcription.
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Affiliation(s)
- Y V Postnikov
- Engelhardt Institute of Molecular Biology, USSR Academy of Sciences, Moscow
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14
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Nigg EA. Nuclear function and organization: the potential of immunochemical approaches. INTERNATIONAL REVIEW OF CYTOLOGY 1988; 110:27-92. [PMID: 3053500 DOI: 10.1016/s0074-7696(08)61847-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- E A Nigg
- Swiss Institute for Experimental Cancer Research, Chemin des Boveresses, Epalinges s/Lausanne
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Bustin M. Immunochemical analysis of the structure and function of chromosomal proteins. CYTOMETRY 1987; 8:251-9. [PMID: 3297563 DOI: 10.1002/cyto.990080304] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Immunochemical approaches are useful in studying the nuclear organization and cellular function of chromosomal components. Antibodies specific to histones and to defined nonhistone proteins have been used to study nucleosome heterogeneity, to visualize the presence of histone in transcriptionally active chromatin, and to isolate DNA sequences associated with specific chromosomal proteins.
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Mendelson E, Landsman D, Druckmann S, Bustin M. Immunofractionation of chromatin regions associated with histone H1o. EUROPEAN JOURNAL OF BIOCHEMISTRY 1986; 160:253-60. [PMID: 2429835 DOI: 10.1111/j.1432-1033.1986.tb09964.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Two monoclonal antibodies, which were elicited against histone H5, bind to purified rat liver chromatin and to rat liver H1o but not to rat liver H1. The monoclonal antibodies were immobilized on CNBr-Sepharose and the resulting immunoaffinity column was used to fractionate rat liver oligonucleosomes. Enzyme-linked immunoabsorbant assay (ELISA) and immunoblotting experiments indicate that the nucleosomes bound to the column were tenfold enriched in their content of H1o. Oligonucleosomes, prepared from the livers of either untreated or 3-methylcholanthrene-treated adult rats, were fractionated on the anti-H1o affinity column. The DNA purified from the unfractionated nucleosomes, from the unbound nucleosomes and from the nucleosomes which were bound to the column was examined with various 32P-labeled probes. A slight enrichment in H1o was detected in the coding region of the rat albumin gene. In contrast DNA which was bound to the column was significantly depleted in sequences hybridizing with total cellular RNA (which contains mostly ribosomal RNA) and with sequences hybridizing to the 3'-terminal region of a cytochrome P-450 gene, which is inducible by the chemical carcinogen 3-methylcholanthrene, regardless of whether isolated from control or from carcinogen-treated rat livers. Our experiments clearly demonstrate that chromatin can be efficiently immunofractionated. The results suggest that the H1o content of chromatin regions containing genes which are constitutively transcribed is not necessarily different from that of regions containing non-transcribed genes and that highly inducible genes may be segregated into chromatin regions which are depleted of H1o.
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Druckmann S, Mendelson E, Landsman D, Bustin M. Immunofractionation of DNA sequences associated with HMG-17 in chromatin. Exp Cell Res 1986; 166:486-96. [PMID: 3743668 DOI: 10.1016/0014-4827(86)90493-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Antibodies specific for chromosomal protein HMG-17 were immobilized on CNBr-Sepharose and the resulting immunoaffinity column was used to purify chromatin segments enriched in HMG-17. The DNA was purified from both the nucleosomal fraction which was bound to the column and from the fraction which was not bound, and examined with DNA probes representing repetitive DNA, non-transcribed genes, transcribed genes and inducible genes. The results suggest that HMG-17 is preferentially associated with DNA sequences coding for genes, regardless of whether they are transcribed, and therefore support the notion that HMG-17 confers specific structural characteristics on selected regions in the genome.
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