The GLH proteins, Caenorhabditis elegans P granule components, associate with CSN-5 and KGB-1, proteins necessary for fertility, and with ZYX-1, a predicted cytoskeletal protein.
The GLH proteins belong to a family of four germline RNA helicases in Caenorhabditis elegans. These putative ATP-dependent enzymes localize to the P granules, which are nonmembranous complexes of protein and RNA exclusively found in the cytoplasm of all C. elegans germ cells and germ cell precursors. To determine what proteins the GLHs bind, C. elegans cDNA libraries were screened by the yeast two-hybrid method, using GLHs as bait. Three interacting proteins, CSN-5, KGB-1, and ZYX-1, were identified and further characterized. GST pull-down assays independently established that these proteins bind GLHs. CSN-5 is closely related to the subunit 5 protein of COP9 signalosomes, conserved multiprotein complexes of plants and animals. RNA interference (RNAi) with csn-5 results in sterile worms with small gonads and no oocytes, a defect essentially identical to that produced by RNAi with a combination of glh-1 and glh-4. KGB-1 is a putative JNK MAP kinase that GLHs bind. A kgb-1 deletion strain has a temperature-sensitive, sterile phenotype characterized by the absence of mature oocytes and the presence of trapped, immature oocytes that have undergone endoreplication. ZYX-1 is a LIM domain protein most like vertebrate Zyxin, a cytoskeletal adaptor protein. In C. elegans, while zyx-1 appears to be a single copy gene, neither RNAi depletion nor a zyx-1 deletion strain results in an obvious phenotype. These three conserved proteins are the first members in each of their families reported to associate with germline helicases. Similar to the loss of GLH-1 and GLH-4, loss of either CSN-5 or KGB-1 causes oogenesis to cease, but does not affect the initial assembly of P granules.
Smith
Pliny
P
Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, 65212, USA.
Leung-Chiu
W M
WM
Montgomery
Ruth
R
Orsborn
April
A
Kuznicki
Kathleen
K
Gressman-Coberly
Emily
E
Mutapcic
Lejla
L
Bennett
Karen
K
D000818:Animals; D000075686:COP9 Signalosome Complex; D017173:Caenorhabditis elegans / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000502:physiology*; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins / Q000502:physiology*; D053487:DEAD-box RNA Helicases; D005298:Fertility / Q000502:physiology*; D048031:JNK Mitogen-Activated Protein Kinases; D008540:Meiosis / Q000502:physiology*; D046912:Multiprotein Complexes; D010447:Peptide Hydrolases; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011506:Proteins / Q000502:physiology; D020365:RNA Helicases / Q000502:physiology*; D020798:Two-Hybrid System Techniques; D060589:Zyxin
C524498:CSN-5 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D046912:Multiprotein Complexes; D011506:Proteins; C532814:ZYX-1 protein, C elegans; D060589:Zyxin; D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; C524496:KGB-1 protein, C elegans; C524497:GLH-1 protein, C elegans; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases