Drosophila histone locus body assembly and function involves multiple interactions

• Type of Material: Article
• Authors: Kaitlin P. Koreski, University of North Carolina Chapel Hill; Leila Rieder, Emory University; Lyndsey M. McLain, University of North Carolina Chapel Hill; Ashlesha Chaubal, University of North Carolina Chapel Hill; William F. Marzluff, University of North Carolina Chapel Hill; Robert J. Duronio, University of North Carolina Chapel Hill
• Language: English
• Date: 2020-07-01
• Publisher: The American Society for Cell Biology
• Publication Version: Final Published Version
• Copyright Statement: © 2020 Koreski et al. “ASCB®,” “The American Society for Cell Biology®,” and “Molecular Biology of the Cell®” are registered trademarks of The American Society for Cell Biology.
• License: Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1091/mbc.E20-03-0176
• Title of Journal or Parent Work: Molecular Biology of the Cell
• Volume: 31
• Issue: 14
• Start Page: 1525
• End Page: 1537
• Grant/Funding Information: This work was supported by National Institutes of Health grant R01GM058921 to R.J.D and W.F.M and F32GM109663, K99HD092625, and R00HD092625 to L.E.R.
• Keywords: Animals; Homozygote; Drosophila Proteins; Transcription, Genetic; Promoter Regions, Genetic; Histones; Genome; RNA, Messenger; Drosophila melanogaster

Abstract

The histone locus body (HLB) assembles at replication-dependent (RD) histone loci and concentrates factors required for RD histone mRNA biosynthesis. The Drosophila melanogaster genome has a single locus comprised of ∼100 copies of a tandemly arrayed 5-kB repeat unit containing one copy of each of the 5 RD histone genes. To determine sequence elements required for D. melanogaster HLB formation and histone gene expression, we used transgenic gene arrays containing 12 copies of the histone repeat unit that functionally complement loss of the ∼200 endogenous RD histone genes. A 12x histone gene array in which all H3-H4 promoters were replaced with H2a-H2b promoters (12xPR) does not form an HLB or express high levels of RD histone mRNA in the presence of the endogenous histone genes. In contrast, this same transgenic array is active in HLB assembly and RD histone gene expression in the absence of the endogenous RD histone genes and rescues the lethality caused by homozygous deletion of the RD histone locus. The HLB formed in the absence of endogenous RD histone genes on the mutant 12x array contains all known factors present in the wild-type HLB including CLAMP, which normally binds to GAGA repeats in the H3-H4 promoter. These data suggest that multiple protein-protein and/or protein-DNA interactions contribute to HLB formation, and that the large number of endogenous RD histone gene copies sequester available factor(s) from attenuated transgenic arrays, thereby preventing HLB formation and gene expression on these arrays.