In Vitro Induction of H1−H1 Histone Cross-Linking by Adenosine Diphosphate−Ribose Polymers

Abstract

It is well-known that H1-H1 interactions are very important for the induction of 30 nm chromatin fiber and that, among all posttranslational modifications, poly(ADP-ribosyl)ation is one of those capable of modifying chromatin structure, mainly through H1 histone. As this protein can undergo both covalent and noncovalent modifications by poly(ADP-ribosyl)ation, our aim was to investigate whether and how ADP-ribose polymers, by themselves, are able to affect the formation of H1-H1 oligomers, which are normally present in a condensed chromatin structure. The results obtained in our in vitro experimental system indicate that ADP-ribose polymers are involved in chromatin decondensation. This conclusion was reached as the result of two different observations: (a) H1 histone molecules can be hosted in clusters on ADP-ribose polymers, as shown by their ability to be chemically cross-linked, and (b) H1 histone has a higher affinity for ADP-ribose polymers than for DNA; ADP-ribose polymers compete, in fact, with DNA for H1 histone binding.

Proteome-wide microarray-based screening of PAR-binding proteins

“…Fifteen proteins, indicated by the points in the upper right shaded corner of the graph in Figure 1C, were observed to have the highest PAR-binding signal intensity (Figure 1C). As expected, known PARbinding proteins such as histones (Panzeter et al, 1992;Reale et al, 2000;Realini and Althaus, 1992) and p53 (Fischbach et al, 2018;Kruger et al, 2019), were among the highest PAR binders. The specificity of the interaction was further underscored by the observation that positively charged lysine-rich histones do not bind measurably to negatively charged poly(A).…”

Poly(ADP-ribosyl)ation and Epigenetics: Is CTCF PARt of the Plot?

“…30,31 On a similar note, free PAR molecules are also able to affect directly the formation of H1-H1 oligomers and therefore regulate processes of chromatin remodeling. 32 Taken together, these data suggest a link between PARlation and epigenetic processes. A further insight into potential molecular mechanisms of these events comes from the observations that apart from histones, a number of key transcription factors, such as p53, 15,33 YY1 34 and CTCF 35 have been documented to be PARlated both, in vivo and in vitro.…”

Chromatin Insulators: Regulatory Mechanisms and Epigenetic Inheritance

“…In this case, there are hints that the modification is a positive regulator of insulator function, as treatment with 3-aminobenzamide, an inhibitor of PARlation, results in loss of insulation. The idea that PARlation regulates CTCF insulation by promoting interactions between insulator sites has not been shown conclusively but appears likely, as PARlation seems to promote protein-protein interactions in other contexts (Reale et al, 2000). Another case of insulator regulation by modulation of protein-protein interaction is the modification of Mod(mdg4)2.2 and CP190 in the Drosophila Su(Hw) insulator complex by addition of SUMO (Small Ubiquitin-like Modifier) (Capelson and Corces, 2006).…”