title: The functioning of the Drosophila CPEB protein Orb is regulated by phosphorylation and requires casein kinase 2 activity.
abstract: The Orb CPEB protein regulates translation of localized mRNAs in Drosophila ovaries. While there are multiple hypo- and hyperphosphorylated Orb isoforms in wild type ovaries, most are missing in orb(F303), which has an amino acid substitution in a buried region of the second RRM domain. Using a proteomics approach we identified a candidate Orb kinase, Casein Kinase 2 (CK2). In addition to being associated with Orb in vivo, we show that ck2 is required for orb functioning in gurken signaling and in the autoregulation of orb mRNA localization and translation. Supporting a role for ck2 in Orb phosphorylation, we find that the phosphorylation pattern is altered when ck2 activity is partially compromised. Finally, we show that the Orb hypophosphorylated isoforms are in slowly sedimenting complexes that contain the translational repressor Bruno, while the hyperphosphorylated isoforms assemble into large complexes that co-sediment with polysomes and contain the Wisp poly(A) polymerase.
authors.affiliation: Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America.
authors.forename: Li Chin
authors.initials: LC
authors.lastname: Wong
authors.forename: Alexandre
authors.initials: A
authors.lastname: Costa
authors.forename: Ian
authors.initials: I
authors.lastname: McLeod
authors.forename: Ali
authors.initials: A
authors.lastname: Sarkeshik
authors.forename: John
authors.initials: J
authors.lastname: Yates
authors.forename: Saw
authors.initials: S
authors.lastname: Kyin
authors.forename: David
authors.initials: D
authors.lastname: Perlman
authors.forename: Paul
authors.initials: P
authors.lastname: Schedl
mesh_terms: D000818:Animals; D047390:Casein Kinase II / Q000378:metabolism*; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D009154:Mutation; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine
chemical_list: D029721:Drosophila Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C089932:orb protein, Drosophila; D014443:Tyrosine; D047390:Casein Kinase II