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T Tarkka

Publications and source records attributed to T Tarkka.

6 recordsLinked to original sources
PubMed1997

Nucleotide and calcium-induced conformational changes in histone H1.

The principal constituents of chromatin, histone H1 (H1) and the nucleosome have essential roles in regulation of eukaryotic gene expression. However, mechanisms for the H1-dependent inactivation and for the ATP-dependent chromatin remodeling upon activation are largely unelucidated. Using circular dichroism (CD) analysis we show that ATP and other nucleotides and Ca2+ induce structural changes in H1. ATP and Ca2+ also induce changes when H1 is interacting with DNA, and the changes in H1 are accompanied by alterations in its DNA interaction. These results suggest that nucleotide and Ca2+ binding may be important for H1-mediated chromatin changes.

Adenine Nucleotides↗
PubMed1995

The ATP/ADP binding domains of actin are conserved in nucleosome complexed with histone H1 and high mobility group-17 protein.

Chromatin has been proposed to share a common evolutionary origin and analogous mechanisms of action with various structures of cytoskeleton such as actin filaments. ATP has been shown to facilitate chromatin remodelling, but the exact site of its interaction with chromatin has not been elucidated. The facts, that ATP binds specifically to actin and promotes its polymerization, led us to characterize the possible domains involved in ATP binding in nucleosome. Comparison of the sequences of actin and the protein components of nucleosome suggests that H2A may contain an adenosine binding site similar to the adenosine motif of actin, H1 and/or H2B phosphate/Ca2+ binding sites corresponding to the phosphate 1 motif of actin, HMG17 a phosphate/Ca2+ binding site corresponding to the phosphate 2 motif of actin. The ability to bind ATP may be involved in the organization of chromatin into inactive solenoid-like structures in vivo.

Actins↗
PubMed1994

Nucleotide recognition by histone H1 involves specific protein structures.

We have reported previously that histone H1 is capable of binding nucleotides such as ATP, GTP, ADP, and GDP in a specific manner. It is demonstrated here using labeling with the uv-crosslinkable ATP analog 8-azido-[alpha-32P]ATP that this ability is a unique characteristic of H1 among the histone proteins. Phosphate analogs such as AlF-4 efficiently counteract the labeling of H1, while they do not compete for labeling of histones H2A, H2B, H3, and H4. Consistent with the assumption that this labeling is due to specific binding, nucleotides competed for the labeling of H1 in a manner similar to labeling of the catalytic subunit of cAMP-dependent protein kinase, casein kinase-II, and heat shock protein-90, all of which are ATP/GTP-binding proteins. The site of nucleotide interaction was subsequently located in a Gly-rich region of H1 which displays homology with the protein kinases, using either radioactive labeling with nucleotide analogs and endoproteinase Glu-C digestion or synthetic peptides corresponding to the putative binding site. The results imply that specific protein structures are involved in nucleotide binding to H1 and that the ability of H1 to bind nucleotides may provide a mechanism for the regulation of eukaryotic gene expression.

Acetyl Coenzyme A↗
PubMed1993

Specific non-enzymatic glycation of the rat histone H1 nucleotide binding site in vitro in the presence of AlF4-. A putative mechanism for impaired chromatin function.

We show here that an aluminium derivative, AlF4-, stimulates glycation of histone H1 selectively in the proximity of its nucleotide-binding site. This adduct formation interferes with nucleoside triphosphate hydrolysis by H1 and with nucleotide modulation of H1 DNA binding. The present mode of aluminium action may in part be responsible for its effects on the chromatin structure and expression of tissue-specific genes, and may constitute a mechanism in the pathogenesis of aluminium-induced encephalopathy and in that of Alzheimer's disease, for example.

Aluminum↗
PubMed1991

Interference of AlF4- with nucleotide and DNA binding of rat histone H1 in vitro. Implications for the pathogenesis of Alzheimer's disease.

We demonstrate here that the H2PO4- analogue AlF4- binds to the nucleotide-binding site of rat liver histone H1 in vitro, and interferes with nucleotide recognition and H1 DNA binding. AlF4- may thus compromise the genetically determined pattern of protein synthesis through binding to H1, the general repressor. The present findings are of interest as a number of studies have implicated aluminium as a factor in the pathogenesis of Alzheimer's disease.

Aluminum↗