Compositional and Conformational Analysis of Sperm Nucleus Basi c Proteins from the Bivalve Mollusk Crassostrea virginic a (original) (raw)
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Histone proteins play essential structural and functional roles in the transition between active and inactive chromatin states. Although histones have a high degree of conservation due to constraints to maintain the overall structure of the nucleosomal octameric core, variants have evolved to assume diverse roles in gene regulation and epigenetic silencing. Histone variants, post-translational modifications and interactions with chromatin remodeling complexes influence DMA replication, transcription, repair and recombination. The authors review recent findings on the structure of chromatin that confirm previous interparticle interactions observed in crystal structures.
Nucleic Acids Research, 2009
In this work we have studied the properties of the novel mouse histone variant H2AL2. H2AL2 was used to reconstitute nucleosomes and the structural and functional properties of these particles were studied by a combination of biochemical approaches, atomic force microscopy (AFM) and electron cryo-microscopy. DNase I and hydroxyl radical footprinting as well as micrococcal and exonuclease III digestion demonstrated an altered structure of the H2AL2 nucleosomes all over the nucleosomal DNA length. Restriction nuclease accessibility experiments revealed that the interactions of the H2AL2 histone octamer with the ends of the nucleosomal DNA are highly perturbed. AFM imaging showed that the H2AL2 histone octamer was complexed with only~130 bp of DNA. H2AL2 reconstituted trinucleosomes exhibited a type of a 'beads on a string' structure, which was quite different from the equilateral triangle 3D organization of conventional H2A trinucleosomes. The presence of H2AL2 affected both the RSC and SWI/SNF remodeling and mobilization of the variant particles. These unusual properties of the H2AL2 nucleosomes suggest a specific role of H2AL2 during mouse spermiogenesis. Correspondence may also be addressed to Stefan Dimitrov. +33 4 76 54 94 73; +33 4 76 54 95 95;
European Journal of Biochemistry, 1977
Proton magnetic resonance, circular dichroism and other studies of whole and cleaved calf thymus histone H1 (formerly F1) reveal the presence of specific folded structures in the region approximately from residue 40-115. Ionic, hydrogen-bond and hydrophobic interactions all appear to contribute to the stability of the structure, which is predicted to contain a-helices in regions 42-55 and 58-75. No evidence was found for 8-structures, either inter or intramolecular, or for any structure formation outside the region 40-115. At 18 "C and a protein concentration of 2 mM the first-order exchange rate between random-coil and structured forms is slower than 80 s-'; at 40 "C the exchange rate is faster than 330 s-The very-lysine-rich histone H 1 (formerly called F1 or I; the nomenclature used in this paper is taken from [I]), exhibits several features which distinguish it from the other histone fractions found in eukaryote chromatin. It has the highest molecular weight (approx. 23000) and has a very high lysine : arginine ratio of over 15 : 1, varying up to 21 : 1 for some subfractions.
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Cold Spring Harbor Symposia on Quantitative Biology, 2004
Eukaryotic DNA associates with an equal amount of protein to form chromatin, the fundamental unit of which is the nucleosome core particle (NCP). An NCP consists of two copies each of the four core histones H2A, H2B, H3, and H4. This histone octamer binds 147 base pairs of DNA around its outer surface in 1.65 tight superhelical turns (Fig. 1A) (Luger et al. 1997; Richmond and Davey 2003). Linker histones and other nonhistone proteins promote or stabilize the folding of nucleosomal arrays into superstructures of increasing complexity and largely unknown architecture (Hansen 2002). Covalent modification of the core histones and variations in the fundamental biochemical composition of nucleosomes distinguish transcriptionally active from inactive chromatin regions, by either changing the structure of the nucleosomes, altering their ability to interact with other protein factors, or modifying their propensity to fold into varying degrees of higher-order structures (or by any combination of the above). Studying the mechanism for establishing distinct chromatin domains is essential to understanding differential regulation of gene expression and all other DNA-de
Interaction of histone H1 from sea urchin sperm with superhelical and relaxed DNA
Molecular Biology Reports, 1985
Complexes of histone H 1 from sea urchin sperm (H I S) and calft hymus (H l T) with superhelical DNA I and relaxed circular DNA I1 have been analyzed by analytical sedimentation. Similar to HIT, the highly basic and relatively arginine-rich histone HIS preferentially interacts with DNA I compared to DNA II under competition conditions. However, HIS induces a stronger aggregation of both forms of DNA than H IT. Below 0.05 M NaC1, the soluble complexes formed by both histones have similar properties, but aggregation proceeds in a different manner: HIS induces a stronger aggregation of DNA II as compared to DNA I, whereas HIT fails to aggregate DNA I.