Male-specific lethal complex of Drosophila targets activated regions of the X chromosome for chromatin remodeling.
The male-specific lethal (MSL) complex of Drosophila is responsible for the presence of a monoacetylated isoform of histone H4 (H4Ac16), found exclusively on the X chromosome of males. This particular covalent modification of histone H4 is correlated with a 2-fold enhancement of the transcription of most X-linked genes in Drosophila males, which is the basis of dosage compensation in this organism. Although widespread along the X chromosome, the MSL complex is not distributed uniformly, as can be seen by the indirect cytoimmunofluorescence staining of larval salivary-gland polytene chromosomes. This distribution pattern has been interpreted as a reflection of the tissue-specific transcriptional activity of the larval salivary gland and as an indication that the MSL complex associates with active chromatin. We have tested this hypothesis by comparing the chromosomal distribution of the complex in two different tissues. We performed this comparison by following the pattern of association of the complex at a specific site on salivary-gland chromosomes during larval development and determining whether an ectopic promoter located in a complex-devoid region of the X chromosome is able to attract the complex upon activation. Our results indicate that, in contrast to other chromatin-remodeling complexes that enhance transcription, the MSL complex targets active chromatin.
Sass
Georgette L
GL
Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA.
Pannuti
Antonio
A
Lucchesi
John C
JC
D000107:Acetylation; D000123:Acetyltransferases / Q000502:physiology; D000818:Animals; D001665:Binding Sites; D002843:Chromatin / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000502:physiology; D004265:DNA Helicases / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology; D004303:Dosage Compensation, Genetic; D029721:Drosophila Proteins / Q000502:physiology*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005260:Female; D051548:Histone Acetyltransferases; D006657:Histones / Q000378:metabolism*; D007814:Larva; D046911:Macromolecular Substances; D008297:Male; D009687:Nuclear Proteins; D009928:Organ Specificity; D010053:Ovary / Q000648:ultrastructure; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D012469:Salivary Glands / Q000648:ultrastructure; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic / Q000235:genetics*; D014960:X Chromosome / Q000378:metabolism*
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006657:Histones; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D014157:Transcription Factors; C070837:mle protein, Drosophila; D000123:Acetyltransferases; D051548:Histone Acetyltransferases; C111063:mof protein, Drosophila; D004265:DNA Helicases