Proteins in chromatin

Olave lA, Reck-Peterson SL, Crabtree GR (2002) Nuclear actin and actin-related proteins in chromatin remodeling. Annu Rev Biochem 71 755-781... 

Abstract Post-synthetic modification of histone proteins in chromatin architecture plays a central... 

The principal proteins in chromatin are the histones, of which there are five main types, called HI, H2A, H2B, H3, and H4. All these proteins contain large numbers of basic amino acid residues, such as lysine and arginine. In the... 

Since the major poly(ADP-ribose) acceptor protein in chromatin and in intact cells is poly(ADP-ribose) polymerase (5, 11, 12), we have studied the interaction of the highly modified polymerase with native and Hl-depleted chromatin in order to define its role as a potential modulator of chromatin structure. When poly(ADP-ribosyl)ated native chromatin was resolved on sucrose gradients, it was found that most of the modified enzyme was... 

The DNA in a eukaryotic cell nucleus during the interphase between cell divisions exists as a nucleoprotein complex called chromatin. The proteins of chromatin fall into two classes histones and nonhistone chromosomal proteins. 

Finally, the binding of specific transcription factors to cognate DNA elements may result in disruption of nucleosomal structure. Many eukaryotic genes have multiple protein-binding DNA elements. The serial binding of transcription factors to these elements—in a combinatorial fashion—may either directly disrupt the structure of the nucleosome or prevent its re-formation or recruit, via protein-protein interactions, multiprotein coactivator complexes that have the ability to covalently modify or remodel nucleosomes. These reactions result in chromatin-level structural changes that in the end increase DNA accessibifity to other factors and the transcription machinery. 

An additional question relating to sites of modification is the possible influence of DNA binding proteins and the conformational changes they induce in DNA as it forms chromatin, which in turn may influence available binding sites for adduct formation. Several studies have investigated the distribution of DNA adducts in chromatin (95-102). although no clear answer for the influence of these proteins has yet emerged. 

Orlando, V. (2000) Mapping chromosomal proteins in vivo by formaldehyde-crosslinked-chromatin immunoprecipitation. Trends Biochem. Sci. 3, 99-104. 

While studying the binding of mercury by chromatin of rats injected with mercuric chloride, the nonhistone chromatin proteins in rat and kidney cell nuclei were shown to be mainly responsible for the mercury deposition [43]. The mercury-binding nonhistone proteins were found to be heterogeneous by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. 

In isolated nuclei from rat liver and kidney, Ni2 + was bound to chromatin, polynucleosomes and to deproteinized DNA [339]. Ni2+ directly interacted with stable binding sites on the DNA molecule in chromatin and was associated with histone and nonhistone nuclear proteins [339, 340]. 

During the course of the article, we will present evidence that the histones constitute part of a self-assembly system (Section IV). In the absence of DNA they retain the information to interact with each other to form a hierarchy of structures with dimensions, periodicities, and intermolecular contacts, compatible with what is known about the protein core of chromatin. This strongly suggests that histone-histone interactions have a fundamental role in chromatin structure. 

Furthermore, there is a striking parallelism between these data and the neutron diffraction data from nucleosomes in 100% D 0 (Pardon et al., 1977 Suau et al., 1977), where scattering from the histone protein dominates, and from core protein in 2 M NaCl solution (Pardon et al., 1978). The above interference phenomenon may well be the explanation for the protein-dominated scattering maximum between 35 and 37 A observed for chromatin and nucleosomes in solution (Pardon et al., 1977 Suau et al., 1977). 

PHD Zn-finger (smart00249) YCSVCGKPDDGGELL QCDGCDRWYHQTCL GPPLLIEEPDGKWYCP KCK Found in nuclear proteins and implicated in chromatin-mediated transcriptional regulation. Tifl-a (NP 003843) 43... 

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