MINI-REVIEW Post-translational modifications of the intrinsically disordered terminal domains of histone H1: effects on secondary structure and chromatin dynamics A. Roque 1 & I. Ponte 1 & P. Suau 1 Received: 9 March 2016 /Revised: 5 April 2016 /Accepted: 7 April 2016 # Springer-Verlag Berlin Heidelberg 2016 Abstract H1 linker histones are involved both in the mainte- nance of chromatin higher-order structure and in gene regula- tion. H1 binds to linker DNA regions on the surface of the nucleosome. In higher eukaryotes, H1 contains three distinct domains: a short N-terminal domain (NTD), a central globular domain, and a long C-terminal domain (CTD). Terminal do- mains determine subtype specificity and to a large extent the linker DNA binding and chromatin condensing properties of histone H1. This review is focused on the recent numerous studies that have provided insights in the role of H1 terminal domains in chromatin dynamics. The N- and C-terminal do- mains behave as intrinsically disordered proteins with coupled binding and folding. We examine the potential kinetic advan- tages of intrinsic disorder in the recognition of the specific H1 binding sites in chromatin. As typical intrinsically disordered regions, H1 terminal domains are post-translationally modi- fied. Post-translational modifications in the NTD determine the interaction of histone H1 with other proteins involved in heterochromatin formation and transcriptional regulation, while phosphorylation by cyclin-dependent kinases modu- lates the secondary structure of the CTD and chromatin con- densation. We review the arguments in favor of the involve- ment of H1 hyperphosphorylation in metaphase chromatin condensation and of partial phosphorylation in interphase chromatin relaxation. In addition, the interplay of histone H1 and other chromatin architectural proteins, such as proteins of the high-mobility group, protamines, and MeCP2, is associat- ed with changes in chromatin structure. Keywords Histone H1 . Intrinsic disorder . Post-translational modifications . Chromatin dynamics . Secondary structure . Chromatin condensation Introduction Histone H1 binds to the surface of the nucleosome and linker DNA. H1 is involved in the modulation of chromatin higher- order structure and gene regulation. In mammals, seven so- matic subtypes (designated H1.0–H1.5 and H1.10), three male germ-line-specific subtypes (H1.6, also called H1t, H1.7, and H1.9), and an oocyte-specific subtype (H1.8) have been iden- tified (Talbert et al. 2012). Despite the overlap of H1 subtype functions, numerous studies suggest their functional differen- tiation (Millán-Ariño et al. 2016; Parseghian 2015; Kowalski and Palyga 2012). Histone H1 is dynamically bound to chromatin in vivo as shown by fluorescence recovery after photobleaching (FRAP) (Misteli et al. 2000; Lever et al. 2000; Th’ng et al. 2005; Raghuram et al. 2009). The residence time of H1 sub- types is variable and may be modulated in part by post- translational modifications (PTMs). FRAP studies have also shown the existence of at least two populations of chromatin- bound H1 with different affinities (Raghuram et al. 2009). H1 has a tripartite structure composed of a central globular domain (GD) (~80 residues) flanked by a short N-terminal domain (NTD) (20–35 residues) and a long C-terminal do- main (CTD) (~100 residues). The GD is highly conserved among subtypes, while the terminal domains are variable in length, amino acid sequence, and PTMs (Parseghian 2015; Ponte et al. 1998). The N- and C-terminal domains are rich in disorder-promoting amino acids, including lysine, serine, proline, and alanine. In the last decade, it has been established that H1 terminal domains are intrinsically disordered regions * P. Suau pere.suau@uab.es 1 Departamento de Bioquímica y Biología Molecular, Facultad de Biociencias, Universidad Autónoma de Barcelona, 08193Bellaterra, Barcelona, Spain Chromosoma DOI 10.1007/s00412-016-0591-8