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J S Zlatanova

Publications and source records attributed to J S Zlatanova.

13 recordsLinked to original sources
PubMed1993

Does histone H1 bind specifically to the nuclear factor I recognition sequence?

The issue of whether histone H1 possesses specificity of binding to certain nucleotide sequences in DNA is of fundamental importance to the suggested role of the linker histone in the regulation of gene transcription. The purpose of the present study was to reinvestigate the specificity of binding of histone H1 to the putative nuclear factor I (NFI) recognition sequence suggested by a previous report in the literature. The interaction of purified mouse liver histone H1 with a synthetic oligonucleotide representing the natural NFI binding site from the adenovirus 2 origin of replication cloned in pBR322 has been studied by filter binding and a solid-phase procedure performed on nitrocellulose filter-immobilized protein dots. No indication of specific interactions of the lysine-rich histone H1 with the NFI recognition sequence was obtained.

Adenoviridae↗
PubMed1992

Antibodies specific to histone H1 inhibit in vitro transcription in isolated mammalian nuclei.

The issue of whether histone H1 is present in transcriptionally active chromatin has been approached by studying the effect specific anti-H1 antibodies have on in vitro transcription in isolated nuclei. To that end, the incorporation of radioactive RNA precursors into trichloroacetic acid-precipitable material was compared for control nuclei and nuclei that had been preincubated with specific anti-H1 antibody populations (whole sera, affinity-purified immunoglobulins and monovalent Fab fragments). The anti-H1 antibodies significantly and reproducibly inhibited the transcriptional activity in isolated nuclei. Experiments were also performed to exclude the possibility that the inhibition observed was due to some long-distance effect of the binding of the antibodies to chromatin. The results are interpreted as indicating that active gene chromatin does contain histone H1.

Animals↗
PubMed1992

Chromatin loops and transcriptional regulation.

The existence of a supermolecular structure in the eukaryotic nucleus, involving loops of chromatin attached at irregularly spaced points to the nuclear matrix, is now well established. Quite a bit is known concerning the DNA sequences involved in the attachment. However, the function of this highly organized structure remains largely unknown. In this review, we attempt to provide an overview of present knowledge of nuclear loop structure, and to critically summarize recent studies that provide new insights as to function. We derive the conclusion that the loop structure is very likely one in which DNA topology can be locally regulated by topoisomerase activity, and is most probably modified during development.

Animals↗
PubMed1991

Antigenic structure of histone H1(0).

In order to study the antigenic structure of histone H1(0) the purified protein from mouse liver was subjected to different chemical and enzymatic treatments (CNBr, acetic acid, trypsin, chymotrypsin). The resulting peptides were fractionated in SDS-containing or acid-urea polyacrylamide gels, transferred by electroblotting onto nitrocellulose paper and probed with specific rabbit anti-H1(0) antiserum. The C-terminal fragments 99-193 (obtained following acetic acid hydrolysis) and 107-193 (obtained by chymotrypsin digestion) also exhibited strong immunoreactivity. Fragment 1-30 (CNBr cleavage) contained antigenic determinants while the shorter fragments 1-22 and 1-28 (acetic acid hydrolysis) failed to show any detectable reactivity. It was concluded that, in contrast to histone H5 whose reactivity is mainly concentrated to the globular domain of the molecule, the antigenic determinants in histone H1(0) are more or less evenly distributed along the polypeptide chain with the possible exception of the short unstructured N-nose.

Acetates↗
PubMed1990

Accessibility of histone H1(0) and its structural domains to antibody binding in extended and folded chromatin.

The aim of this work was to study the accessibility of histone H1(0) and its structural domains to antibody binding in high molecular mass chromatin fragments of different conformations. Three types of specific antibody populations were used: (1) anti-H1(0) which reacted with antigenic determinants situated along the whole polypeptide chain, (2) anti-GH5 or anti-GH1(0) which recognized epitopes located in the globular region of H1(0) and (3) anti-C-tail antibodies reacting specifically with fragment 99-193 of the protein molecule. The immunoreactivity of the chromatin-bound antigen was investigated by solid-phase ELISA performed on glutaraldehyde-cross-linked chromatin and by an inhibition assay carried out with native chromatin in solution. The results of both methods were unidirectional and showed that: (1) the accessibility of H1(0) did not change with the compaction of the fiber; (2) the G-domain was not accessible to antibodies either in the relaxed or in the condensed state of the fragments, (3) the binding of the C-terminus-specific antibodies was different for isolated monosomes and for the chromatin fiber and (4) the degree of exposure of the epitopes of H1(0) in chromatin was much less than that of histone H1.

Animals↗
PubMed1990

Immunochemical approaches to the study of histone H1 and high mobility group chromatin proteins.

This review is an attempt to summarize all existing data on histone H1 and high mobility group proteins obtained with immunochemical methods. The following issues are treated consecutively: production of specific antisera to these protein groups, antigenic structure of the polypeptide chains, use of antibodies for the identification, the quantitative estimation and the study of the tissue- and species-specificity of the proteins. Special attention is devoted to the studies of the localization of the respective antigens in the cell, the nucleus, the chromosomes and the interphase chromatin. The use of specific antibodies for the elucidation of the role these proteins play in such basic cellular processes as proliferation and differentiation, replication and transcription is also discussed. It becomes clear that the use of immunochemical approaches in the study of specific chromatin proteins both at the level of the protein molecule and at the level of chromatin can be a powerful tool for the resolution of a number of specific problems. The field is very promising and will undoubtedly develop intensely in the nearest future.

Animals↗
PubMed1990

Cytoplasmic pool of histone H1 in mammalian cells.

Two types of cell populations, nondividing mouse liver cells and exponentially growing Friend erythroleukemia cells, were studied for the presence of a histone H1 pool in the cytoplasm. Purified cytoplasmic fractions were extracted with 5% perchloric acid and the resulting protein preparation was characterized by two types of electrophoresis, gel filtration, peptide mapping, ELISA and immunoblotting. The occurrence of significant quantities of H1 in isolated cytoplasmic fractions was confirmed by indirect immunofluorescence on whole cells. The existence of a cytoplasmic pool of H1 contrasts with the lack of detectable amounts of core histones in the cytoplasm. This indicates that the observed H1 pool is not just a reflection of its cytoplasmic synthesis but probably has some functional significance.

Animals↗
PubMed1988

Supercoils in plant DNA: nucleoid sedimentation studies.

Plant nuclei have been studied with respect to the three-dimensional structure of DNA. Nucleoids derived from nuclei by non-ionic detergent and high salt treatment were analysed by sedimentation in a series of sucrose gradients containing increasing amounts of the intercalating agent ethidium bromide. In addition the nucleoid sedimentation behaviour was investigated following gamma irradiation. The results show that plant DNA is supercoiled, as is the DNA from the other eukaryotes studied, and contains approximately the same concentration of superhelical turns but probably relatively fewer DNA superhelical loops. The plant nuclear populations in all cases studied give rise to two distinct nucleoid bands. These have been characterized by electron microscopy and by their DNA and protein content. The possible origin of the two bands is discussed.

Cell Nucleus↗
PubMed1983

Chemical crosslinking of histone H1o to histone neighbours in nuclei and chromatin.

Crosslinking of histones in mouse liver nuclei and extended chromatin with a bifunctional reagent leads to the formation of H1-H1o heterodimers as well as H1o-H1o homodimers. H1o can be also crosslinked to the core histones. Thus, the location of histone H1o within the basic repeating chromatin structure seems to be analogous to that of H1 histone.

Animals↗
PubMed1983

Presence of histone H1o-related fraction in chicken liver.

The lysine-rich histones of chicken liver were studied in order to see whether a protein similar to mammalian histone H1o was present in this lower vertebrate. The following biochemical methods were used: sodium dodecylsulphate and acid-urea electrophoresis, gel exclusion chromatography on BioGel P100, and ion-exchange chromatography on BioRex 70. Specific polyclonal antibodies were elicited against purified mouse liver H1o and chicken erythrocyte H5, and applied for the further characterization of the chicken H1 subfractions obtained chromatographically. The results from microcomplement fixation and enzyme-linked immunosorbent assays showed that the presumptive chicken liver H1o shared common antigenic determinants with the mammalian H1o and the chicken liver H5. Based on the combined biochemical and immunological evidence, we conclude that an H1o-like protein is present in quiescent differentiated avian cells. The data of Smith et al. [34], who did not find this specific lysine-rich histone in resting chicken cells, are discussed.

Animals↗
PubMedDate not supplied

Interaction of histone H1 with cis-platinum modified DNA.

Cis-diamminedichloroplatinum(II) (cis-DDP) is known as an effective anticancer drug. Its therapeutic effect is supposed to be a consequence of the covalent binding to DNA. A number of cellular proteins were found to bind selectively to DNA modified by cis-DDP (but not by its isomer trans-DDP). Here we present our observations on interaction of the linker histone H1 with cis- and trans-DDP modified DNA fragments. The results afford new experimental information about the preferential binding of histone H1 to cis-DDP-distorted DNAs versus trans-DDP modified ones.

Cisplatin↗