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Chromatin marks are recognized by distinct binding modules, many of which are embedded in multidomain proteins. How the different functionalities of such complex chromatin modulators are regulated is often unclear. Here, we delineated the interplay of the H3 amino terminus– and K9me-binding activities of the multidomain hUHRF1 protein. We show that the phosphoinositide PI5P interacts simultaneously with two distant flexible linker regions connecting distinct domains of hUHRF1. The binding is dependent on both, the polar head group, and the acyl part of the phospholipid and induces a conformational rearrangement juxtaposing the H3 amino terminus and K9me3 recognition modules of the protein. In consequence, the two features of the H3 tail are bound in a multivalent, synergistic manner. Our work highlights a previously unidentified molecular function for PI5P outside of the context of lipid mono- or bilayers and establishes a molecular paradigm for the allosteric regulation of complex, multidomain chromatin modulators by small cellular molecules.

Metal ions present in cellular microenvironment have been implicated as drivers of aggregation of amyloid forming proteins. Zinc (Zn2+) ions have been reported to directly interact with α-synuclein (AS), a causative agent of Parkinson’s disease and other neurodegenerative diseases, and promote its aggregation. AS is a small intrinsically disordered protein (IDP) i.e., understanding molecular factors that drive its misfolding and aggregation has been challenging since methods used routinely to study protein structure are not effective for IDPs. Here, we report the atomic details of Zn2+ binding to AS at physiological conditions using proton-less NMR techniques that can be applied to highly dynamic systems like IDPs. We also examined how human serum albumin (HSA), the most abundant protein in human blood, binds to AS and whether Zn2+ and/or ionic strength affect this. We conclude that Zn2+ enhances the anti-aggregation chaperoning role of HSA that relies on protecting the hydrophobic N-terminal and NAC regions of AS, rather than polar negatively charged C-terminus. This suggested a previously undocumented role of Zn2+ in HSA function and AS aggregation.

Chromatin signaling relies on a plethora of posttranslational modifications (PTM) of the histone proteins which package the long DNA molecules of our cells in reoccurring units of nucleosomes. Determining the biological function and molecular working mechanisms of different patterns of histone PTMs requires access to various chromatin substrates of defined modification status. Traditionally, these are achieved by individual reconstitution of single nucleosomes or arrays of nucleosomes in conjunction with modified histones produced by means of chemical biology. Here, we report an alternative strategy for establishing a library of differentially modified nucleosomes that bypasses the need for many individual syntheses, purification and assembly reactions by installing modified histone tails on ligation-ready, immobilized nucleosomes reconstituted in a single batch. Using the ligation-ready nucleosome strategy with sortase-mediated ligation for histone H3 and intein splicing for histone H2A, we generated libraries of up to 280 individually modified nucleosomes in 96-well plate format. Screening these libraries for the effects of patterns of PTMs onto the recruitment of a well-known chromatin factor, HP1 revealed a previously unknown long-range cross-talk between two modifications. H3S28 phosphorylation enhances recruitment of the HP1 protein to the H3K9 methylated H3-tail only in nucleosomal context. Detailed structural analysis by NMR measurements implies negative charges at position 28 to increase nucleosomal H3-tail dynamics and flexibility. Our work shows that ligation-ready nucleosomes enable unprecedented access to the ample space and complexity of histone modification patterns for the discovery and dissection of chromatin regulatory principles., 280 different patterns of histone modifications were installed in preassembled nucleosomes using PTS and SML enabling screening of readout crosstalk.

Chromatin marks are recognized by distinct binding modules many of which are embedded in multidomain proteins or complexes. How the different protein functionalities of complex chromatin modulators are regulated is often unclear. Using a combination of biochemical, biophysical and structural approaches we delineated the regulation of the H3unmodified and H3K9me binding activities of the multidomain UHRF1 protein. The phosphoinositide PI5P interacts with two distant flexible linker regions of UHRF1 in a mode that is dependent on the polar head group and the acyl part of the phospholipid. The associated conformational rearrangements stably position the H3unmodified and H3K9me3 histone recognition modules of UHRF1 for multivalent and synergistic binding of the H3 tail. Our work highlights a novel molecular function for PI5P outside of the context of lipid mono- or bilayers and establishes a molecular paradigm for the allosteric regulation of complex, multidomain chromatin modulators by small cellular molecules.

Amplification of chromosomal region 8p11–12 is a common genetic alteration that has been implicated in the aetiology of lung squamous cell carcinoma (LUSC)1–3. The FGFR1 gene is the main candidate driver of tumorigenesis within this region4. However, clinical trials evaluating FGFR1 inhibition as a targeted therapy have been unsuccessful5. Here we identify the histone H3 lysine 36 (H3K36) methyltransferase NSD3, the gene for which is located in the 8p11–12 amplicon, as a key regulator of LUSC tumorigenesis. In contrast to other 8p11–12 candidate LUSC drivers, increased expression of NSD3 correlated strongly with its gene amplification. Ablation of NSD3, but not of FGFR1, attenuated tumour growth and extended survival in a mouse model of LUSC. We identify an LUSC-associated variant NSD3(T1232A) that shows increased catalytic activity for dimethylation of H3K36 (H3K36me2) in vitro and in vivo. Structural dynamic analyses revealed that the T1232A substitution elicited localized mobility changes throughout the catalytic domain of NSD3 to relieve auto-inhibition and to increase accessibility of the H3 substrate. Expression of NSD3(T1232A) in vivo accelerated tumorigenesis and decreased overall survival in mouse models of LUSC. Pathological generation of H3K36me2 by NSD3(T1232A) reprograms the chromatin landscape to promote oncogenic gene expression signatures. Furthermore, NSD3, in a manner dependent on its catalytic activity, promoted transformation in human tracheobronchial cells and growth of xenografted human LUSC cell lines with amplification of 8p11–12. Depletion of NSD3 in patient-derived xenografts from primary LUSCs containing NSD3 amplification or the NSD3(T1232A)-encoding variant attenuated neoplastic growth in mice. Finally, NSD3-regulated LUSC-derived xenografts were hypersensitive to bromodomain inhibition. Thus, our work identifies NSD3 as a principal 8p11–12 amplicon-associated oncogenic driver in LUSC, and suggests that NSD3-dependency renders LUSC therapeutically vulnerable to bromodomain inhibition. The histone H3K36 methyltransferase NSD3, which is associated with the common 8p11–12 chromosomal amplification, is an oncogenic driver in lung squamous cell carcinoma.

The DNA-binding protein H-NS is a pleiotropic gene regulator in gram-negative bacteria. Through its capacity to sense temperature and other environmental factors, H-NS allows pathogens like Salmonella to adapt their gene expression, and hence toxicity and biological responses, to their presence inside or outside warm-blooded hosts. To investigate how this sensing mechanism may have evolved to fit different bacterial lifestyles, we compared H-NS orthologs from bacteria that infect humans, plants, and insects, and from bacteria that live on a deep-sea hypothermal vent. The combination of biophysical characterization, high-resolution proton-less NMR spectroscopy and molecular simulations revealed, at an atomistic level, how the same general mechanism was adapted to specific habitats and lifestyles. In particular, we demonstrate how environment-sensing characteristics arise from specifically positioned intra- or intermolecular electrostatic interactions. Our integrative approach clarified the mechanism for H-NS–mediated environmental sensing and suggests that it resulted from the exaptation of an ancestral protein feature.

Summary The etiological role of NSD2 enzymatic activity in solid tumors is unclear. Here we show that NSD2, via H3K36me2 catalysis, cooperates with oncogenic KRAS signaling to drive lung adenocarcinoma (LUAD) pathogenesis. In vivo expression of NSD2E1099K, a hyperactive variant detected in individuals with LUAD, rapidly accelerates malignant tumor progression while decreasing survival in KRAS-driven LUAD mouse models. Pathologic H3K36me2 generation by NSD2 amplifies transcriptional output of KRAS and several complementary oncogenic gene expression programs. We establish a versatile in vivo CRISPRi-based system to test gene functions in LUAD and find that NSD2 loss strongly attenuates tumor progression. NSD2 knockdown also blocks neoplastic growth of PDXs (patient-dervived xenografts) from primary LUAD. Finally, a treatment regimen combining NSD2 depletion with MEK1/2 inhibition causes nearly complete regression of LUAD tumors. Our work identifies NSD2 as a bona fide LUAD therapeutic target and suggests a pivotal epigenetic role of the NSD2-H3K36me2 axis in sustaining oncogenic signaling.