title: Distinct self-interaction domains promote Multi Sex Combs accumulation in and formation of the Drosophila histone locus body.
abstract: Nuclear bodies (NBs) are structures that concentrate proteins, RNAs, and ribonucleoproteins that perform functions essential to gene expression. How NBs assemble is not well understood. We studied the Drosophila histone locus body (HLB), a NB that concentrates factors required for histone mRNA biosynthesis at the replication-dependent histone gene locus. We coupled biochemical analysis with confocal imaging of both fixed and live tissues to demonstrate that the Drosophila Multi Sex Combs (Mxc) protein contains multiple domains necessary for HLB assembly. An important feature of this assembly process is the self-interaction of Mxc via two conserved N-terminal domains: a LisH domain and a novel self-interaction facilitator (SIF) domain immediately downstream of the LisH domain. Molecular modeling suggests that the LisH and SIF domains directly interact, and mutation of either the LisH or the SIF domain severely impairs Mxc function in vivo, resulting in reduced histone mRNA accumulation. A region of Mxc between amino acids 721 and 1481 is also necessary for HLB assembly independent of the LisH and SIF domains. Finally, the C-terminal 195 amino acids of Mxc are required for recruiting FLASH, an essential histone mRNA-processing factor, to the HLB. We conclude that multiple domains of the Mxc protein promote HLB assembly in order to concentrate factors required for histone mRNA biosynthesis.
authors.affiliation: Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599.
authors.forename: Esteban A
authors.initials: EA
authors.lastname: Terzo
authors.affiliation: Department of Biology, University of North Carolina, Chapel Hill, NC 27599.
authors.forename: Shawn M
authors.initials: SM
authors.lastname: Lyons
authors.affiliation: Department of Biology, University of North Carolina, Chapel Hill, NC 27599.
authors.forename: John S
authors.initials: JS
authors.lastname: Poulton
authors.affiliation: Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599.
authors.forename: Brenda R S
authors.initials: BR
authors.lastname: Temple
authors.affiliation: Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599 Department of Biology, University of North Carolina, Chapel Hill, NC 27599 Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599 Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599 Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599.
authors.forename: William F
authors.initials: WF
authors.lastname: Marzluff
authors.affiliation: Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599 Department of Biology, University of North Carolina, Chapel Hill, NC 27599 Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599 Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599 Department of Genetics, University of North Carolina, Chapel Hill, NC 27599 duronio@med.unc.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Duronio
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D029721:Drosophila Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006657:Histones / Q000235:genetics* / Q000378:metabolism; D018613:Microscopy, Confocal; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary; D014158:Transcription, Genetic / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D006657:Histones; C000604521:Mxc protein, Drosophila; D025521:Tumor Suppressor Proteins