Domains of heterochromatin protein 1 required for Drosophila melanogaster heterochromatin spreading.
Centric regions of eukaryotic genomes are packaged into heterochromatin, which possesses the ability to spread along the chromosome and silence gene expression. The process of spreading has been challenging to study at the molecular level due to repetitious sequences within centric regions. A heterochromatin protein 1 (HP1) tethering system was developed that generates "ectopic heterochromatin" at sites within euchromatic regions of the Drosophila melanogaster genome. Using this system, we show that HP1 dimerization and the PxVxL interaction platform formed by dimerization of the HP1 chromo shadow domain are necessary for spreading to a downstream reporter gene located 3.7 kb away. Surprisingly, either the HP1 chromo domain or the chromo shadow domain alone is sufficient for spreading and silencing at a downstream reporter gene located 1.9 kb away. Spreading is dependent on at least two H3K9 methyltransferases, with SU(VAR)3-9 playing a greater role at the 3.7-kb reporter and dSETDB1 predominately acting at the 1.9 kb reporter. These data support a model whereby HP1 takes part in multiple mechanisms of silencing and spreading.
Hines
Karrie A
KA
Department of Biochemistry, University of Iowa, Iowa City, 52242, USA.
Cryderman
Diane E
DE
Flannery
Kaitlin M
KM
Yang
Hongbo
H
Vitalini
Michael W
MW
Hazelrigg
Tulle
T
Mizzen
Craig A
CA
Wallrath
Lori L
LL
D000818:Animals; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000502:physiology*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics*; D020868:Gene Silencing; D017930:Genes, Reporter; D006570:Heterochromatin / Q000378:metabolism*; D008722:Methods; D008780:Methyltransferases; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary
D002868:Chromosomal Proteins, Non-Histone; D029721:Drosophila Proteins; D006570:Heterochromatin; D000090266:Chromobox Protein Homolog 5; D008780:Methyltransferases