The Caenorhabditis elegans peb-1 gene encodes a novel DNA-binding protein involved in morphogenesis of the pharynx, vulva, and hindgut.
Gene expression in the Caenorhabditis elegans pharynx is regulated in part by organ-specific signals, which in the myo-2 gene target a regulatory sequence called the C sub-element. C sub-element activity requires the organ specification factor PHA-4, a winged-helix transcription factor expressed in all pharyngeal cells. To identify additional factors involved in pharyngeal organogenesis, we performed a yeast one-hybrid screen for C sub-element binding proteins. Here we describe the novel factor PEB-1, which is coexpressed with PHA-4 in many pharyngeal cell types, including muscles, epithelial cells, marginal cells, and glands, but is undetectable in the pharyngeal nervous system. PEB-1 is also detected outside the pharynx in cells surrounding the rectum and vulva, as well as in the germ line. Reduction of peb-1 function using RNAi results in morphological defects in the somatic tissues in which peb-1 is expressed. We have mapped the PEB-1 DNA-binding domain to a 158-residue region, which is unrelated to known DNA-binding proteins but shares some sequence similarity to the Drosophila Mod(mdg4) proteins. PEB-1 specifically recognizes a site in the C subelement that partially overlaps the PHA-4 binding site. Both the PEB-1 and the PHA-4 binding sites are necessary for strong C sub-element enhancer activity in some cells in which these factors are coexpressed. In contrast the PEB-1 site is dispensable for C sub-element activity in pharyngeal neurons. We propose that PEB-1 functions with PHA-4 to activate target gene expression in cells in which they are coexpressed.
Thatcher
J D
JD
Department of Biological Sciences (M/C 567), University of Illinois at   Chicago, 900 S. Ashland Avenue, Chicago, Illinois 60607, USA.   
Fernandez
A P
AP
Beaster-Jones
L
L
Haun
C
C
Okkema
P G
PG
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004064:Digestive System / Q000196:embryology; D004625:Embryo, Nonmammalian / Q000502:physiology*; D005260:Female; D015723:Gene Library; D008969:Molecular Sequence Data; D009024:Morphogenesis; D010614:Pharynx / Q000196:embryology; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014844:Vulva / Q000196:embryology
D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; D020033:Protein Isoforms; C420182:peb-1 protein, C elegans