title: Context-dependent regulation of Hox protein functions by CK2 phosphorylation sites.
abstract: Variations in Hox protein sequences and functions have been proposed to contribute to evolutionary changes in appendage shape and number in crustaceans and insects. One model is that insect Hox proteins of the Ultrabithorax (UBX) ortholog class evolved increased abilities to repress Distal-less (Dll) transcription and appendage development in part through the loss of serine and threonine residues in casein kinase 2 (CK2) phosphorylation sites. To explore this possibility, we constructed and tested the appendage repression function of chimeric proteins with insertions of different CK2 consensus sites or phosphomimetics of CK2 sites in C-terminal regions of Drosophila melanogaster UBX. Our results indicate that CK2 sites C-terminal to the homeodomain can inhibit the appendage repression functions of UBX proteins, but only in the context of specific amino acid sequences. Our results, combined with previous findings on evolutionary changes in Hox protein, suggest how intra-protein regulatory changes can diversify Hox protein function, and thus animal morphology.
authors.affiliation: Neuroscience & Aging Research Center, The Burnham Institute for Medical Research, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Ouarda
authors.initials: O
authors.lastname: Taghli-Lamallem
authors.forename: Cheryl
authors.initials: C
authors.lastname: Hsia
authors.forename: Matthew
authors.initials: M
authors.lastname: Ronshaugen
authors.forename: William
authors.initials: W
authors.lastname: McGinnis
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D001665:Binding Sites; D019521:Body Patterning / Q000235:genetics; D047390:Casein Kinase II / Q000378:metabolism*; D002678:Chimera / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D004625:Embryo, Nonmammalian; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013909:Thorax / Q000196:embryology; D014157:Transcription Factors / Q000235:genetics
chemical_list: D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C066177:Ubx protein, Drosophila; D047390:Casein Kinase II