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Abstract
In this chapter, a short evolutionary history and comparative analysis of sperm nuclear basic proteins (SNBPs) in marine invertebrates are presented based on some of the most recent publications in the field and building upon previously published reviews on the topic. Putative functions of SNBPs in sperm chromatin beyond DNA packaging will also be discussed with a primary focus on outstanding research questions.In somatic cells of all metazoans, DNA is packaged into tightly folded and dynamically accessible chromatin by canonical histones H2A, H2B, H3 and H4. Sperm chromatin of many animals, on the other hand, is organised by small yet structurally highly heterogeneous proteins called SNBPs, which can package sperm DNA on their own or in combination with each other. In extreme cases, sperm chromatin is condensed into a volume 6-10 times smaller than that of a somatic nucleus. SNBPs are classified into three major groups: H1 histone-type proteins (H-type SNBPs), protamines (P-type SNBPs) and protamine-like proteins (PL-type SNBPs). P-type SNBPs are mostly found in vertebrates, while PL-type SNBPs are ubiquitous in many invertebrate phyla. PL-type and P-type SNBPs evolved from histone H-type SNBP precursors through vertical evolution. Porifera, Ctenophora and Crustacea, Echinoidea (phylum Echinodermata) and Hydrozoa (phylum Hydrozoa) lack SNBPs. Echinoidea and Hydrozoa, however, evolved novel nucleosomal histone variants with specific roles during spermatogenesis. Seemingly, chromatin condensation plays a critical role in the silencing and tight packing of the genome within the sperm nucleus of most animals. However, the question of what necessitates the compaction of some sperm DNA beyond classical nucleosomal packaging while other sperm function using 'normal' histones remains unanswered to date.
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Affiliation(s)
- Anna Török
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland.
| | - Sebastian G Gornik
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland.
- Centre for Organismal Studies (COS), Heidelberg University, Heidelberg, Germany.
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2
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Matsushita M, Ochiai H, Suzuki KIT, Hayashi S, Yamamoto T, Awazu A, Sakamoto N. Dynamic changes in the interchromosomal interaction of early histone gene loci during development of sea urchin. J Cell Sci 2017; 130:4097-4107. [PMID: 29084822 DOI: 10.1242/jcs.206862] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 10/22/2017] [Indexed: 12/21/2022] Open
Abstract
The nuclear positioning and chromatin dynamics of eukaryotic genes are closely related to the regulation of gene expression, but they have not been well examined during early development, which is accompanied by rapid cell cycle progression and dynamic changes in nuclear organization, such as nuclear size and chromatin constitution. In this study, we focused on the early development of the sea urchin Hemicentrotus pulcherrimus and performed three-dimensional fluorescence in situ hybridization of gene loci encoding early histones (one of the types of histone in sea urchin). There are two non-allelic early histone gene loci per sea urchin genome. We found that during the morula stage, when the early histone gene expression levels are at their maximum, interchromosomal interactions were often formed between the early histone gene loci on separate chromosomes and that the gene loci were directed to locate to more interior positions. Furthermore, these interactions were associated with the active transcription of the early histone genes. Thus, such dynamic interchromosomal interactions may contribute to the efficient synthesis of early histone mRNA during the morula stage of sea urchin development.
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Affiliation(s)
- Masaya Matsushita
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Hiroshi Ochiai
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.,JST, PRESTO, Higashi-Hiroshima 739-8530, Japan
| | - Ken-Ichi T Suzuki
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Sayaka Hayashi
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.,Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Akinori Awazu
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.,Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Naoaki Sakamoto
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan .,Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
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3
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Abstract
Two-dimensional (2D) polyacrylamide gel electrophoresis (PAGE) systems employing combinations of acetic acid/urea (AU), acetic acid/urea/Triton X-100 (AUT) and sodium dodecyl sulfate (SDS) gel formulations are uniquely effective for resolution of histone variants and their modified derivatives. Coupled with Western transfer methods using modification-specific antibodies and recent advances in mass spectrometry, 2D PAGE emerges as a versatile tool for histone purification and analysis. This chapter describes 2D PAGE gel systems appropriate for histone proteins, including detailed procedures for designing, running, and staining gels. Methods for electrophoretic transfer of histones from AUTxSDS and AUTxAU 2D gels are described and evaluated. Alternatively, methods are provided for obtaining highly purified protein samples from fixed and stained gels via electroelution of proteins from specific gel spots.
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Affiliation(s)
- George R Green
- Department of Pharmaceutical Sciences, Mercer University College of Pharmacy and Health Sciences, Atlanta, GA, USA
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4
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del Valle LJ. In vitro decondensation of the sperm chromatin in Holothuria tubulosa (sea cucumber) not affecting proteolysis of basic nuclear proteins. Dev Growth Differ 2005; 47:333-42. [PMID: 16026541 DOI: 10.1111/j.1440-169x.2005.00805.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sea urchin and sea star oocyte extracts contain proteolytic activities that are active against sperm basic nuclear proteins (SNBP). This SNBP degradation has been related to the decondensation of sperm chromatin as a possible model to male pronuclei formation. We have studied the presence of this proteolytic activity in Holothuria tubulosa (sea cucumber) and its possible relationship with sperm nuclei decondensation. The mature oocyte extracts from H. tubulosa contain a proteolytic activity to SNBP located in the macromolecular fraction of the egg-jelly layer. SNBP degradation occurred both on sperm nuclei and on purified SNBP, histones being more easily degraded than protein Ø(o) (sperm-specific protein). SNBP degradation was found to be dependent on concentration, incubation time, presence of Ca(2+), pH, and this activity could be a serine-proteinase. Thermal denaturalization of the oocyte extracts (80 degrees C, 10-15 min) inactivates its proteolytic activity on SNBP but does not affect sperm nuclei decondensation. These results would suggest that sperm nuclei decondensation occurs by a mechanism different from SNBP degradation. Thus, the sperm nuclei decondensation occurs by a thermostable factor(s) and the removal of linker SNBP (H1 and protein Ø(o)) will be a first condition in the process of sperm chromatin remodeling.
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Affiliation(s)
- Luis J del Valle
- Center de Biotecnología Molecular, Departament d'Enginyeria Química, EUETIB, Consorci Escola Industrial de Barcelona, Universitat Politècnica de Catalunya, 08036 Barcelona, Spain.
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5
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Green GR, Ferlita RR, Walkenhorst WF, Poccia DL. Linker DNA destabilizes condensed chromatin. Biochem Cell Biol 2001. [DOI: 10.1139/o01-115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The contribution of the linker region to maintenance of condensed chromatin was examined in two model systems, namely sea urchin sperm nuclei and chicken red blood cell nuclei. Linkerless nuclei, prepared by extensive digestion with micrococcal nuclease, were compared with Native nuclei using several assays, including microscopic appearance, nuclear turbidity, salt stability, and trypsin resistance. Chromatin in the Linkerless nuclei was highly condensed, resembling pyknotic chromatin in apoptotic cells. Linkerless nuclei were more stable in low ionic strength buffers and more resistant to trypsin than Native nuclei. Analysis of histones from the trypsinized nuclei by polyacrylamide gel electrophoresis showed that specific histone H1, H2B, and H3 tail regions stabilized linker DNA in condensed nuclei. Thermal denaturation of soluble chromatin preparations from differentially trypsinized sperm nuclei demonstrated that the N-terminal regions of histones Sp H1, Sp H2B, and H3 bind tightly to linker DNA, causing it to denature at a high temperature. We conclude that linker DNA exerts a disruptive force on condensed chromatin structure which is counteracted by binding of specific histone tail regions to the linker DNA. The inherent instability of the linker region may be significant in all eukaryotic chromatins and may promote gene activation in living cells.Key words: chromatin condensation, sea urchin sperm, chicken red blood cell, nuclei, linker DNA, histone variants, micrococcal nuclease, nucleosome, trypsin, gel electrophoresis.
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6
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Green GR. Phosphorylation of histone variant regions in chromatin: Unlocking the linker? Biochem Cell Biol 2001. [DOI: 10.1139/o01-075] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Histone variants illuminate the behavior of chromatin through their unique structures and patterns of postsynthetic modification. This review examines the literature on heteromorphous histone structures in chromatin, structures that are primary targets for histone kinases and phosphatases in vivo. Special attention is paid to certain well-studied experimental systems: mammalian culture cells, chicken erythrocytes, sea urchin sperm, wheat sprouts, Tetrahymena, and budding yeast. A common theme emerges from these studies. Specialized, highly basic structures in histone variants promote chromatin condensation in a variety of developmental situations. Before, and sometimes after condensed chromatin is formed, the chromatin is rendered soluble by phosphorylation of the heteromorphous regions, preventing their interaction with linker DNA. A simple structural model accounting for histone variation and phosphorylation is presented.Key words: phosphorylation, histone variants, chromatin, linker DNA.
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7
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Latham KE. Mechanisms and control of embryonic genome activation in mammalian embryos. INTERNATIONAL REVIEW OF CYTOLOGY 1999; 193:71-124. [PMID: 10494621 DOI: 10.1016/s0074-7696(08)61779-9] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Activation of transcription within the embryonic genome (EGA) after fertilization is a complex process requiring a carefully coordinated series of nuclear and cytoplasmic events, which collectively ensure that the two parental genomes can be faithfully reprogrammed and restructured before transcription occurs. Available data indicate that inappropriate transcription of some genes during the period of nuclear reprogramming can have long-term detrimental effects on the embryo. Therefore, precise control over the time of EGA is essential for normal embryogenesis. In most mammals, genome activation occurs in a stepwise manner. In the mouse, for example, some transcription occurs during the second half of the one-cell stage, and then a much greater phase of genome activation occurs in two waves during the two-cell stage, with the second wave producing the largest onset of de novo gene expression. Changes in nuclear structure, chromatin structure, and cytoplasmic macromolecular content appear to regulate these periods of transcriptional activation. A model is presented in which a combination of cell cycle-dependent events and both translational and posttranslational regulatory mechanisms within the cytoplasm play key roles in mediating and regulating EGA.
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Affiliation(s)
- K E Latham
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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8
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Abstract
The delivery of the paternal genome to the egg is a primary goal of fertilization. In preparation for this step, the nucleus of the developing spermatozoon undergoes extensive morphological and biochemical transformations during spermatogenesis to yield a tightly compacted sperm nucleus. These modifications are essentially reversed during fertilization. As a result, the incorporated sperm nucleus undergoes many steps in the egg cytoplasm as it develops into a male pronucleus. The sperm nucleus (1) loses its nuclear envelope, (2) undergoes nucleoprotein remodeling, (3) decondenses and increases in size, (4) becomes more spherical, (5) acquires a new nuclear envelope, and (6) becomes functionally competent to synthesize DNA and RNA. These changes are coordinate with meiotic processing of the maternal chromatin, and often result in behaviors asynchronous with the maternal chromatin. For example, in eggs fertilized during meiosis, the sperm nucleus decondenses while the maternal chromatin remains condensed. A model is presented that suggests some reasons why this puzzling behavior exists. Defects in any of the processes attending male pronuclear development often result in infertility. New assisted reproductive technologies have been developed that ensure delivery of the sperm nucleus to the egg cytoplasm so that a healthy embryo is produced. An emerging challenge is to further characterize the molecular mechanisms that control sperm nuclear transformations and link these to causes of human infertility. Further understanding of this basic process promises to revolutionize our understanding of the mystery of the beginning of new life.
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Affiliation(s)
- S J Wright
- Department of Biology, University of Dayton, Ohio 45469, USA
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9
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Brandt WF, Schwager SU, Rodrigues JA, Busslinger M. Isolation and amino acid sequence analysis reveal an ancient evolutionary origin of the cleavage stage (CS) histones of the sea urchin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 247:784-91. [PMID: 9288898 DOI: 10.1111/j.1432-1033.1997.00784.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The cleavage stage (CS) H1, H2A, and H2B histones of the sea urchin, which have previously been identified by their distinct electrophoretic mobility on Triton/acid/urea gels, are known to be maternally expressed during oogenesis and have been implicated in chromatin remodeling of the male pronucleus following fertilization. Here, we describe the isolation of these three CS histones by reverse-phase HPLC chromatography. Moreover, a novel CS H3 protein was identified by the same purification procedure. A low incorporation of radioactive amino acids into the CS histones during early development revealed that the bulk of these proteins in the blastula embryo are derived from the maternal pool of the egg. Amino acid analysis, together with the previously described electrophoretic mobilities, unequivocally identified the purified proteins as CS histones. Peptide sequence analysis confirmed the novel nature of the CS variants as they are distantly related to the early, late, and sperm histone subtypes of the sea urchin. The CS H1 protein displays highest sequence similarity with the H1M (B4) histone of Xenopus laevis, indicating that the frog H1M protein may be a vertebrate homologue of the CS H1 histone. These data suggest an ancient evolutionary origin and wide distribution of the CS histone variants.
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Affiliation(s)
- W F Brandt
- Department of Biochemistry, University of Cape Town, Rondebosch, Republic of South Africa
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10
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Mandl B, Brandt WF, Superti-Furga G, Graninger PG, Birnstiel ML, Busslinger M. The five cleavage-stage (CS) histones of the sea urchin are encoded by a maternally expressed family of replacement histone genes: functional equivalence of the CS H1 and frog H1M (B4) proteins. Mol Cell Biol 1997; 17:1189-200. [PMID: 9032246 PMCID: PMC231844 DOI: 10.1128/mcb.17.3.1189] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The cleavage-stage (CS) histones of the sea urchin are known to be maternally expressed in the egg, have been implicated in chromatin remodeling of the male pronucleus following fertilization, and are the only histone variants present in embryonic chromatin up to the four-cell stage. With the help of partial peptide sequence information, we have isolated and identified CS H1, H2A, H2B, H3, and H4 cDNAs from egg poly(A)+ mRNA of the sea urchin Psammechinus miliaris. All five CS proteins correspond to replacement histone variants which are encoded by replication-independent genes containing introns, poly(A) addition signals, and long nontranslated sequences. Transcripts of the CS histone genes could be detected only during oogenesis and in development up to the early blastula stage. The CS proteins, with the exception of H4, are unique histones which are distantly related in sequence to the early, late, and sperm histone subtypes of the sea urchin. In contrast, the CS H1 protein displays highest sequence homology with the H1M (B4) histone of Xenopus laevis. Both H1 proteins are replacement histone variants with very similar developmental expression profiles in their respective species, thus indicating that the frog H1M (B4) gene is a vertebrate homolog of the CS H1 gene. These data furthermore suggest that the CS histones are of ancient evolutionary origin and may perform similar conserved functions during oogenesis and early development in different species.
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Affiliation(s)
- B Mandl
- Research Institute of Molecular Pathology, Vienna, Austria
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11
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Affiliation(s)
- D Poccia
- Department of Biology, Amherst College, Massachusetts 01002, USA
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12
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Leonardson KE, Levy SB. Distribution of globin genes and histone variants in micrococcal nuclease-generated subfractions of chromatin from Friend erythroleukemia cells at different malignant states. J Cell Biochem 1994; 54:110-21. [PMID: 8126082 DOI: 10.1002/jcb.240540112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The distribution of the alpha and beta-globin genes and histone variants was examined in micrococcal nuclease-generated chromatin fractions of three Friend murine erythroleukemia cell types differing in malignant potential and inducibility to erythroid differentiation. A preferential concentration of globin gene sequences, as compared to satellite DNA, was noted in a physiological salt-soluble, histone H1-depleted, mononucleosomal chromatin fraction (Sup 120) in all Friend cell types, even those in which the globin gene was not capable of transcriptional activation by chemical induction. The level of globin gene enrichment in the Sup 120 fraction was highest in the most malignant and inducible cell type. The chemical induction of erythroid differentiation in this cell line did not change the distribution of globin genes in the chromatin fractions. The Sup 120 chromatin fraction prepared from mouse brain nuclei was not enriched in globin genes. Besides the previously reported low H2A. 1/H2A.2 ratio [Blankstein and Levy: Nature 260:638-640, 1976], chromatin from the most tumorigenic cell type showed the lowest H2B.2 to H2B.1 ratio, highest levels of histone H4 acetylation, and the most pronounced change in relative amounts of two major electrophoretic bands of histone H1 variants as compared to the less malignant cell types. The histone variant content of the micrococcal nuclease-generated chromatin fractions from the three Friend cell types reflected the core histone variant differences for the respective intact nuclei. However, the electrophoretic separation of mononucleosomes by size revealed several classes with different H2A variant ratios. The results demonstrate the existence of structural differences in globin gene and histone variants in erythroleukemia cell chromatin associated with distinguishable phenotypes during malignant cell progression.
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Affiliation(s)
- K E Leonardson
- Department of Medicine and Molecular Biology, Tufts University School of Medicine, New England Medical Center, Boston, Massachusetts 02111
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13
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Affiliation(s)
- M Wiekowski
- Department of Molecular Biology, Schering-Plough Corporation, Kenilworth, New Jersey 07033
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14
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Abstract
Nucleoplasmin is necessary and sufficient for the initial stage of Xenopus sperm decondensation in egg extracts. In this article we show that sperm decondensation is accompanied by loss of two sperm-specific basic proteins (X and Y) and gain of histones H2A and H2B, resulting in nucleosome formation. Purified nucleoplasmin alone removes X and Y and assembles purified H2A and H2B on decondensing sperm chromatin, forming nucleosome cores. Immunodepletion of nucleoplasmin from extract prevents removal of X and Y and addition of H2A and H2B, while adding back nucleoplasmin restores decondensation and X and Y removal. Thus, nucleoplasmin acts as both an assembly and a disassembly factor for remodeling sperm chromatin at fertilization.
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Affiliation(s)
- A Philpott
- Wellcome/CRC Institute of Cancer and Developmental Biology, University of Cambridge, England
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15
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Banerjee S, Bennion GR, Goldberg MW, Allen TD. ATP dependent histone phosphorylation and nucleosome assembly in a human cell free extract. Nucleic Acids Res 1991; 19:5999-6006. [PMID: 1945884 PMCID: PMC329058 DOI: 10.1093/nar/19.21.5999] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Physiologically spaced nucleosome formation in HeLa cell extracts is ATP dependent. ATP hydrolysis is required for chromatin assembly on both linear and covalently closed circular DNA. The link between the phosphorylation state of histones and nucleosome formation has been examined and we demonstrate that in the absence of histone phosphorylation no stable and regularly spaced nucleosomes are formed. Phosphorylated H3 stabilizes the nucleosome core; while phosphorylation of histone H2a is necessary to increase the linker length between nucleosomes from 0 to approximately 45 bp. Histone H1 alone, whether phosphorylated or unphosphorylated, does not increase the nucleosome repeat length in the absence of core histone phosphorylation. Phosphorylations of H1 and H3 correlate with condensation of chromatin. Maximum ATP hydrolysis which is necessary to increase the periodicity of nucleosomes from approximately 150 to approximately 185 bp, not only inhibits H1 and H3 phosphorylation but facilitates their dephosphorylation.
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Affiliation(s)
- S Banerjee
- Department of Pathology, Royal Veterinary College, University of London, UK
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16
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Longo FJ. Gamete interactions and the fate of sperm organelles in fertilized echinoderm eggs. JOURNAL OF ELECTRON MICROSCOPY TECHNIQUE 1991; 17:246-65. [PMID: 2045961 DOI: 10.1002/jemt.1060170303] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Investigations of gamete fusion, sperm entry and the fate of the sperm nucleus, plasma membrane, mitochondrion, and axonemal complex in fertilized echinoderm eggs are reviewed. The timing of gamete fusion with respect to the onset of electrical activity characteristic of the activated egg and the affects of fixation conditions on the stability of fusing membranes are discussed. Observations from investigations using cationized ferritin labeled gametes and immunogold cytochemistry to demonstrate the mixing of sperm plasma membrane components within the egg plasma membrane, in particular along the surface of the fertilization cone, are compared with results from studies in somatic cells. Transformations of the sperm nucleus into a male pronucleus, consisting of sperm nuclear envelope breakdown, chromatin dispersion, and formation of a pronuclear envelope, are correlated with recent biochemical observation of similar processes in other cellular systems. Fates of the sperm mitochondrion and axonemal complex are examined.
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Affiliation(s)
- F J Longo
- Department of Anatomy, University of Iowa, Iowa City 52242
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17
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Vodicka M, Green GR, Poccia DL. Sperm histones and chromatin structure of the "primitive" sea urchin Eucidaris tribuloides. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1990; 256:179-88. [PMID: 2280247 DOI: 10.1002/jez.1402560208] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The "primitive" sea urchin Eucidaris tribuloides resembles the advanced sea urchins (euechinoids) in many respects, yet some features of its biochemistry and morphogenesis are more similar to other echinoderms such as starfish or sea cucumbers. Two unique characteristics of the sperm chromatin of all known euechinoids are an extremely long average nucleosomal repeat length and the presence of two male germ-line-specific histone variants, Sp H1 and Sp H2B. Histone composition and nucleosomal repeat length of the sperm chromatin of Eucidaris were compared to those of several euechinoids and a starfish. Eucidaris sperm chromatin contained large H1 and H2B histone variants typical of euechinoids. The H1 was about nine amino acids smaller than Sp H1 of the advanced urchin Strongylocentrotus purpuratus. Its Sp H2B molecules were the same size as in the euechinoids. Peptide maps showed that N-terminal regions of Sp H1 and Sp H2B contained repeating basic amino acid motifs characteristic of euechinoids. The smaller size of Eucidaris H1 is accounted for by a smaller C-terminal region. The repeat length of Eucidaris sperm chromatin was slightly shorter than that of two euechinoids, but significantly larger than starfish, which lacks a large H2B. The Sp H2B gene of Eucidaris was expressed during spermatogenesis in the same cell types as for S. purpuratus. Thus Sp histone subtype expression and chromatin structure in this distantly related echinoid closely resemble the euechinoids. The presence of an Sp H2B and a very long repeat length appear to be characteristic of the echinoids only.
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Affiliation(s)
- M Vodicka
- Department of Biology, Amherst College, Massachusetts 01002
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18
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Poccia D, Pavan W, Green GR. 6DMAP inhibits chromatin decondensation but not sperm histone kinase in sea urchin male pronuclei. Exp Cell Res 1990; 188:226-34. [PMID: 2159403 DOI: 10.1016/0014-4827(90)90164-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Treatment of sea urchin eggs for 10 min prior to fertilization with the kinase inhibitor 6DMAP (6-dimethylaminopurine) reversibly inhibits swelling and loss of conical morphology of the male pronucleus. Male pronuclei inhibited with 1 mM 6DMAP for 25 min undergo phosphorylation of Sp H1 and Sp H2B histones as fully as do control nuclei. Therefore, Sp histone kinase, whose target sequences resemble those of the M-phase histone kinase, is not inhibited by 6DMAP, and Sp histone phosphorylation, although it may be necessary, is not sufficient for chromatin decondensation.
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Affiliation(s)
- D Poccia
- Department of Biology, Amherst College, Massachusetts 01002
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19
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Hill CS, Thomas JO. Core histone-DNA interactions in sea urchin sperm chromatin. The N-terminal tail of H2B interacts with linker DNA. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 187:145-53. [PMID: 2298202 DOI: 10.1111/j.1432-1033.1990.tb15288.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A three-stage chemical modification procedure [Lambert, S. F. & Thomas, J. O. (1986) Eur. J. Biochem. 160, 191-201; Thomas, J. O. & Wilson, C. M. (1986) EMBO J. 5, 3531-3537] for selectively radiolabelling lysine residues that interact with DNA has been used to investigate core histone--DNA interactions in sea urchin sperm chromatin, in particular to determine the binding site of the long N-terminal domain of sperm-specific H2B. Comparison of the patterns of radiolabelling of core histones from extended chromatin and nucleosome core particles (which lack linker DNA) reveals the regions of the histones involved in interactions with the linker. The results show that the N-terminal domain of H2B is bound to DNA outside the 146-bp nucleosome core, presumably to the linker DNA. H2A and H4 make no substantial contacts with the linker in extended chromatin; the N-terminal tail of H4 is bound within the core particle, but the N-terminal tail of H2A is not bound in core particles or in extended chromatin, and may therefore have a role in higher-order structure. H3, like H2B, makes contacts with DNA outside the 146-bp nucleosome core in its N-terminal region, as well as elsewhere, and probably interacts with the two 10-bp extensions that complete the two turns of DNA in the nucleosome and/or with the linker.
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Affiliation(s)
- C S Hill
- Department of Biochemistry, University of Cambridge, England
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20
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Martínez-Salas E, Linney E, Hassell J, DePamphilis ML. The need for enhancers in gene expression first appears during mouse development with formation of the zygotic nucleus. Genes Dev 1989; 3:1493-506. [PMID: 2558965 DOI: 10.1101/gad.3.10.1493] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Microinjection of the firefly luciferase gene coupled to a thymidine kinase (tk) promoter provided a quantitative assay to evaluate the requirements for gene expression in individual mouse oocytes and embryos. Polyoma virus (PyV) enhancers had no effect on the level of gene expression or competition for transcription factors as long as the DNA remained either in the oocyte germinal vesicle or the pronuclei of one-cell embryos. Expression of injected genes could be observed in pronuclei because the signal that normally triggers zygotic gene expression in two-cell embryos still occurred in one-cell embryos arrested in S phase. However, when the tk promoter was injected into zygotic nuclei of two-cell embryos, enhancers increased the number of embryos that expressed luciferase as well as the level of luciferase activity per embryo. PyV enhancer mutation F101, selected for growth in mouse embryonal carcinoma F9 cells, stimulated expression in developing two-cell embryos about seven times better than the wild-type PyV enhancer and competed effectively for factors required for transcription. These results were consistent with the fact that enhancers are required to activate the PyV origin of DNA replication in developing two-cell embryos but not in one-cell embryos. The maximum levels of gene expression in oocytes, one-cell embryos, and developing two-cell embryos (1:67:21) were inversely related to the extent of chromatin assembly, but the need for enhancers was independent of chromatin assembly. Therefore, it appears that the need for enhancers to activate promoters or origins of replication results from some negative regulatory factor that first appears as a component of zygotic nuclear structure.
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Affiliation(s)
- E Martínez-Salas
- Department of Cell and Developmental Biology, Roche Research Center, Nutley, New Jersey 07110
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Abstract
Phosphorylation of cleavage stage (CS) histones was studied during the first cell cycle in male pronuclei of the sea urchin. Histone CS H2A rapidly incorporated 32PO4 during the replication period, but not before. Peptide mapping and amino acid analysis of radiolabelled CS H2A showed that phosphorylation occurred mainly on serine residues located in the C-terminal region of the molecule. When DNA replication was inhibited with aphidicolin both CS H2A and CS H2B accumulated in male pronuclei at the same rate as in the control culture, whereas accumulation of H3 and H4 histones was reduced. Incorporation of 32PO4 by CS H2A doubled when DNA synthesis was inhibited with aphidicolin. Thus phosphorylation of CS H2A was correlated with transport of CS histones from the egg storage pool to the male pronucleus, but not with chromatin synthesis, indicating that this event precedes nucleosome formation. A role for phosphorylation and dephosphorylation of the CS H2A C-terminal region in modulating transport of stored CS histone dimers and their assembly into nucleosomes is discussed.
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Affiliation(s)
- G R Green
- Department of Biology, Webster Center for Biological Science, Amherst College, Massachusetts 01002
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Hough-Evans BR, Britten RJ, Davidson EH. Mosaic incorporation and regulated expression of an exogenous gene in the sea urchin embryo. Dev Biol 1988; 129:198-208. [PMID: 3165895 DOI: 10.1016/0012-1606(88)90174-1] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A fusion gene construct in which the bacterial chloramphenicol acetyltransferase (CAT) gene is controlled by CyIIIa actin gene cis-regulatory sequences was injected into unfertilized eggs of the sea urchin Strongylocentrotus purpuratus. The distribution of CAT DNA sequences was measured directly by in situ hybridization in squashed 24-hr blastula preparations derived from these eggs. Earlier studies had shown that stable mosaic incorporation of the exogenous DNA occurs during cleavage, after which the exogenous sequences replicate at approximately the pace of the host cell genomes. The fractions of embryonic cells observed in this study to include CAT DNA sequences imply that their stable incorporation into a replicating nuclear form occurs most often in a single cell at the 3rd or 4th cleavage stages, though it may occur as early as 2nd cleavage, or as late as 7th cleavage. Corroborative measurements were carried out by the same method on squashed preparations of embryos at earlier stages, and by in situ hybridizations of CAT mRNA, both in dissociated embryos and in cytological sections of 72-hr pluteus-stage embryos. Hybridizations to CAT mRNA and to CAT DNA were carried out on alternate sections of several embryos. The results confirm unequivocally that although CAT mRNA appears only in the aboral ectoderm in embryos derived from eggs injected with the CyIIIa.CAT fusion gene, the exogenous sequences are indeed present, though silent, in the various other cell types of the late embryo.
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Affiliation(s)
- B R Hough-Evans
- Division of Biology, California Institute of Technology, Pasadena 91125
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Abstract
Trypanosoma cruzi chromatin is not condensed in chromosomes during mitosis. In previous studies a characteristic H 1 was not found in SDS or in acid-urea-PAGE. Consequently, it was proposed that the particular behavior of T. cruzi chromatin in dividing cells was due to the absence of an H 1 histone. In the present work, histones from this parasite were systematically characterized by spectrofluorometric analysis, amino acid composition, PAGE in one and in two dimensions, differential extraction with PCA and TCA, immunological cross-reactivity with antisera, and immunoblotting. We conclude that T. cruzi contains all five histones, H 1 presenting solubility and immunological properties similar to those in other species, but with a particular electrophoretic mobility in Triton-PAGE. Thus an explanation other than the absence of H 1 should be offered in order to understand the behavior of T. cruzi chromatin during mitosis. Moreover, histone variants were described by two-dimensional PAGE. The presence of histone variants suggests that they may participate in the regulation of cell proliferation and differentiation of this parasite, as it has been postulated for higher eukaryotes.
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Affiliation(s)
- G C Toro
- Department of Cell Biology and Genetics, School of Medicine, University of Chile, Santiago
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Abstract
Transitions in the histone complement of nuclei during sea urchin spermatogenesis were investigated by two-dimensional gel electrophoresis. Nuclei were isolated from male gonads of individuals differing in degree of maturity. Unlike protamines, the sea urchin sperm-specific histone variants Sp H1 and Sp H2B appear early in spermatogenesis, well before spermatid differentiation, as the predominant representatives of their classes. Both proteins are phosphorylated from their first appearance until the last steps of spermiogenesis, when the highly condensed late spermatid nuclei become spermatozoan nuclei. Phosphorylation of serine occurs mostly (Sp H1) or entirely (Sp H2B) on the N-terminal portions of these molecules. We conclude that phosphorylated sperm-specific histone variants in the sea urchin function in spermatocytes during meiosis and are the major histones present during replication and transcription in some spermatogonia as well. We propose that the dephosphorylation of Sp H1 and Sp H2B in late spermatids is not primarily responsible for spermatid chromatin condensation but instead may act to stabilize the chromatin of the spermatozoon or aid in the final shaping of the sperm nucleus.
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Kopecný V, Babusík P, Tesarík J, Pavlok A. Selective association of some hamster-egg-synthesized proteins with decondensing human sperm chromatin. HISTOCHEMISTRY 1986; 84:197-200. [PMID: 3710829 DOI: 10.1007/bf00499833] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Zona-free hamster eggs were fertilized in vitro with human spermatozoa in a culture medium enriched with either 3H-arginine or 3H-tryptophan. Autoradiography was used to investigate decondensing sperm heads and all pronuclei for the presence of newly synthesized, 3H-labelled proteins. In the case of 3H-arginine-labelled proteins, an intense accumulation of radioactivity was detected in all autoradiograms of chromatin structures. On the other hand, no comparable accumulation was seen for 3H-tryptophan-labelled proteins up to the progressed-pronucleus stage. It is concluded that, as a part of changes of the nucleoproteins in decondensing sperm chromatin, there is an accumulation in the male (as well as in the female) pronucleus of basic nuclear proteins synthesized by the egg during fertilization. Since non-histone, 3H-tryptophan-labelled proteins were not incorporated in the same way, these 3H-arginine-labelled proteins accumulating in pronuclear chromatin during the earliest phase of pronucleus formation are probably histones.
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Wu RS, Panusz HT, Hatch CL, Bonner WM. Histones and their modifications. CRC CRITICAL REVIEWS IN BIOCHEMISTRY 1986; 20:201-63. [PMID: 3519076 DOI: 10.3109/10409238609083735] [Citation(s) in RCA: 213] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Histones constitute the protein core around which DNA is coiled to form the basic structural unit of the chromosome known as the nucleosome. Because of the large amount of new histone needed during chromosome replication, the synthesis of histone and DNA is regulated in a complex manner. During RNA transcription and DNA replication, the basic nucleosomal structure as well as interactions between nucleosomes must be greatly altered to allow access to the appropriate enzymes and factors. The presence of extensive and varied post-translational modifications to the otherwise highly conserved histone primary sequences provides obvious opportunities for such structural alterations, but despite concentrated and sustained effort, causal connections between histone modifications and nucleosomal functions are not yet elucidated.
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Poccia D. Remodeling of nucleoproteins during gametogenesis, fertilization, and early development. INTERNATIONAL REVIEW OF CYTOLOGY 1986; 105:1-65. [PMID: 3539853 DOI: 10.1016/s0074-7696(08)61061-x] [Citation(s) in RCA: 199] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Killian CE, Bland CE, Kuzava JM, Nishioka D. Effects of aphidicolin on premature condensation of sperm chromosomes in fertilized sea urchin eggs. Exp Cell Res 1985; 158:519-24. [PMID: 3924642 DOI: 10.1016/0014-4827(85)90475-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Unfertilized Strongylocentrotus purpuratus eggs may be treated with ammonia to initiate maternal DNA replication and the maternal cell cycle. When these eggs are polyspermically fertilized 75 min after the beginning of ammonia treatment, the nuclei of the fertilizing spermatozoa undergo premature chromosome condensation (PCC) in an apparent attempt to conform to the advanced maternal cell cycle. PCC is inhibited if maternal DNA replication is blocked by exposing the eggs to aphidicolin but will proceed if this exposure begins after replication is complete. Additionally, PCC will proceed in ammonia-activated, polyspermically fertilized anucleate merogons in the continuous presence of aphidicolin. These results suggest that the direct inhibitory effect of aphidicolin may well be limited to the replication of DNA and that the unreplicated maternal nucleus itself exerts negative control over the development of chromosome-condensing conditions in the maternal cytoplasm.
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Poccia D, Wolff R, Kragh S, Williamson P. RNA synthesis in male pronuclei of the sea urchin. BIOCHIMICA ET BIOPHYSICA ACTA 1985; 824:349-56. [PMID: 2580559 DOI: 10.1016/0167-4781(85)90042-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Transcription in male pronuclei of fertilized sea urchin eggs was measured by comparison of [3H]uridine incorporation into RNA in polyspermic, monospermic and activated eggs under conditions where uptake of the isotope and conversion to UTP were equivalent. RNA accumulation from male pronuclei begins by S phase of the first cell cycle. Initiation of this RNA synthesis does not require DNA synthesis. A major fraction of the newly synthesized transcripts are mRNAs coding for early embryo (alpha-) histones. In addition, several other unidentified transcripts are detected by gel electrophoresis. The pattern of RNA transcription remains constant for at least 4 h post-fertilization. These results demonstrate that specific transcription of male pronuclear sequences is activated in the first cell cycle following fertilization.
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Green GR, Poccia DL. Phosphorylation of sea urchin sperm H1 and H2B histones precedes chromatin decondensation and H1 exchange during pronuclear formation. Dev Biol 1985; 108:235-45. [PMID: 3972178 DOI: 10.1016/0012-1606(85)90026-0] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Immediately following fertilization in the sea urchin, sperm-specific histones Sp H1 and Sp H2B are phosphorylated. Then, in parallel with chromatin decondensation, nearly all phosphorylated Sp H1 is lost from the pronuclear chromatin, with the concurrent assimilation of the egg phosphoprotein CS H1. Chemical cleavage of in vivo labeled Sp H1 and Sp H2B shows that serine phosphorylation occurs in the unusually long N-terminal region of these proteins. These regions contain tandemly repeated tetra- and pentapeptide units each containing serine, proline, and two basic amino acids. It is proposed that sperm chromatin decondensation may require prior phosphorylation of these unusual N-terminal regions, whose function in the mature sperm may be to condense or stabilize its highly compact chromatin.
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