title: Interaction between the Drosophila heterochromatin proteins SUUR and HP1.
abstract: SUUR (Suppressor of Under-Replication) protein is responsible for late replication and, as a consequence, for DNA underreplication of intercalary and pericentric heterochromatin in Drosophila melanogaster polytene chromosomes. However, the mechanism by which SUUR slows down the replication process is not clear. To identify possible partners for SUUR we performed a yeast two-hybrid screen using full-length SUUR as bait. This identified HP1, the well-studied heterochromatin protein, as a strong SUUR interactor. Furthermore, we have determined that the central region of SUUR is necessary and sufficient for interaction with the C-terminal part of HP1, which contains the hinge and chromoshadow domains. In addition, recruitment of SUUR to ectopic HP1 sites on chromosomes provides evidence for their association in vivo. Indeed, we found that the distributions of SUUR and HP1 on polytene chromosomes are interdependent: both absence and overexpression of HP1 prevent SUUR from chromosomal binding, whereas SUUR overexpression causes redistribution of HP1 to numerous sites occupied by SUUR. Finally, HP1 binds to intercalary heterochromatin when histone methyltransferase activity of SU(VAR)3-9 is increased. We propose that interaction with HP1 is crucial for the association of SUUR with chromatin.
authors.affiliation: Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia.
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Pindyurin
authors.forename: Lidiya V
authors.initials: LV
authors.lastname: Boldyreva
authors.forename: Victor V
authors.initials: VV
authors.lastname: Shloma
authors.forename: Tatiana D
authors.initials: TD
authors.lastname: Kolesnikova
authors.forename: Galina V
authors.initials: GV
authors.lastname: Pokholkova
authors.forename: Evgeniya N
authors.initials: EN
authors.lastname: Andreyeva
authors.forename: Elena N
authors.initials: EN
authors.lastname: Kozhevnikova
authors.forename: Igor G
authors.initials: IG
authors.lastname: Ivanoschuk
authors.forename: Ekaterina A
authors.initials: EA
authors.lastname: Zarutskaya
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Demakov
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Gorchakov
authors.forename: Elena S
authors.initials: ES
authors.lastname: Belyaeva
authors.forename: Igor F
authors.initials: IF
authors.lastname: Zhimulev
mesh_terms: D000818:Animals; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D002875:Chromosomes / Q000378:metabolism* / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D006570:Heterochromatin / Q000378:metabolism* / Q000648:ultrastructure; D063150:Polycomb Repressive Complex 1; D020798:Two-Hybrid System Techniques
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006570:Heterochromatin; C066770:Pc protein, Drosophila; C464850:SuUR protein, Drosophila; C452193:heterochromatin protein 1, Drosophila; D063150:Polycomb Repressive Complex 1