Mutations that prevent or mimic persistent post-translational modifications of the histone H3 globular domain cause lethality and growth defects in Drosophila.

Jessica K. Tyler,Hillary K. Graves,Matthew Lagarde,Pingping Wang,Zhihong Chen

doi:10.1186/s13072-016-0059-3

Jessica K. Tyler, Hillary K. Graves + Show 3 more

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https://doi.org/10.1186/s13072-016-0059-3

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Abstract

Background Understanding the function of histone post-translational modifications is the key to deciphering how genomic activities are regulated. Among the least well-understood histone modifications in vivo are those that occur on the surface of the globular domain of histones, despite their causing the most profound structural alterations of the nucleosome in vitro. We utilized a Drosophila system to replace the canonical histone genes with mutated histone transgenes.ResultsMutations predicted to mimic or prevent acetylation on histone H3 lysine (K) 56, K115, K122, and both K115/K122, or to prevent or mimic phosphorylation on H3 threonine (T) 118 and T80, all caused lethality, with the exception of K122R mutants. T118 mutations caused profound growth defects within wing discs, while K115R, K115Q, K56Q, and the K115/K122 mutations caused more subtle growth defects. The H3 K56R and H3 K122R mutations caused no defects in growth, differentiation, or transcription within imaginal discs, indicating that H3 K56 acetylation and K122 acetylation are dispensable for these functions. In agreement, we found the antibody to H3 K122Ac, which was previously used to imply a role for H3 K122Ac in transcription in metazoans, to be non-specific in vivo.ConclusionsOur data suggest that chromatin structural perturbations caused by acetylation of K56, K115, or K122 and phosphorylation of T80 or T118 are important for key developmental processes.Electronic supplementary materialThe online version of this article (doi:10.1186/s13072-016-0059-3) contains supplementary material, which is available to authorized users.

Highlights

Understanding the function of histone post-translational modifications is the key to deciphering how genomic activities are regulated
Chisquared analyses show that the difference in frequency of emergence of flies from pupae for the WT and mutant flies is statistically significant (Fig. 1c). These results indicate that histone H3 residues K56, T80, K115, T118, and K122, and potentially their post-translational modification, are essential for Drosophila development, with each functioning at different stages of development
Mutation of H3 residues K56, T80, K115, T118, and K122 results in lethality in Drosophila Given that the modifications H3 K56Ac, T80p, K115Ac, T118p, and K122Ac occur at histone surfaces that normally mediate histone–DNA interactions or potentially nucleosome–nucleosome interactions (Fig. 1a), we were interested in determining their importance in a metazoan using the Drosophila system

Summary

Introduction

Understanding the function of histone post-translational modifications is the key to deciphering how genomic activities are regulated. Of the histone H3 globular domain modifications, acetylation of lysine 56 (K56Ac) which is conserved from yeast to humans is the best studied. It has been shown functionally that H3 K56Ac promotes the assembly and disassembly of nucleosomes in yeast, leading to efficient DNA repair, replication, and transcription [6,7,8]. Direct study of H3 K56Ac function in metazoan cells has been limited to immunolocalization, where H3 K56Ac levels in flies and humans increase at regions undergoing transcription and DNA repair, suggesting that H3 K56Ac may have similar roles in metazoans as it does in yeast [9,10,11]. The levels of H3 K56Ac in mammalian cells is much lower than in yeast and to date the function of H3 K56Ac has not been directly examined in vivo beyond yeast

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