title: The sperm surface localization of the TRP-3/SPE-41 Ca2+ -permeable channel depends on SPE-38 function in Caenorhabditis elegans.
abstract: Despite undergoing normal development and acquiring normal morphology and motility, mutations in spe-38 or trp-3/spe-41 cause identical phenotypes in Caenorhabditis elegans-mutant sperm fail to fertilize oocytes despite direct contact. SPE-38 is a novel, four-pass transmembrane protein and TRP-3/SPE-41 is a Ca(2+)-permeable channel. Localization of both of these proteins is confined to the membranous organelles (MOs) in undifferentiated spermatids. In mature spermatozoa, SPE-38 is localized to the pseudopod and TRP-3/SPE-41 is localized to the whole plasma membrane. Here we show that the dynamic redistribution of TRP-3/SPE-41 from MOs to the plasma membrane is dependent on SPE-38. In spe-38 mutant spermatozoa, TRP-3/SPE-41 is trapped within the MOs and fails to reach the cell surface despite MO fusion with the plasma membrane. Split-ubiquitin yeast-two-hybrid analyses revealed that the cell surface localization of TRP-3/SPE-41 is likely regulated by SPE-38 through a direct protein-protein interaction mechanism. We have identified sequences that influence the physical interaction between SPE-38 and TRP-3/SPE-41, and show that these sequences in SPE-38 are required for fertility in transgenic animals. Despite the mislocalization of TRP-3/SPE-41 in spe-38 mutant spermatozoa, ionomycin or thapsigargin induced influx of Ca(2+) remains unperturbed. This work reveals a new paradigm for the regulated surface localization of a Ca(2+)-permeable channel.
authors.affiliation: Waksman Institute of Microbiology, 190 Frelinghuysen Road, Piscataway, NJ 08854, USA. guna@waksman.rutgers.edu
authors.forename: Gunasekaran
authors.initials: G
authors.lastname: Singaravelu
authors.forename: Indrani
authors.initials: I
authors.lastname: Chatterjee
authors.forename: Sina
authors.initials: S
authors.lastname: Rahimi
authors.forename: Marina K
authors.initials: MK
authors.lastname: Druzhinina
authors.forename: Lijun
authors.initials: L
authors.lastname: Kang
authors.forename: X Z Shawn
authors.initials: XZ
authors.lastname: Xu
authors.forename: Andrew
authors.initials: A
authors.lastname: Singson
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015388:Organelles / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; D015220:Calcium Channels; D008565:Membrane Proteins; C502564:Spe-38 protein, C elegans; C477118:spe-41 protein, C elegans; D002118:Calcium