Functional Properties of the unc-64 Gene Encoding aCaenorhabditis elegans Syntaxin*
- From the ‡Department of Biology, Fujita Health University, Toyoake, Aichi 470-11, ‖Department of Nutrition, School of Medicine, Tokushima University, Tokushima 770, and the Departments of ¶Biochemistry and **Physical Information, Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920, Japan
Abstract
Phenotypes of Caenorhabditis elegans unc-18 and unc-64 gene mutations are similar. Whileunc-18 is known to be essential for normal synaptic transmission (Hosono, R., Hekimi, S., Kamiya, Y., Sassa, T., Murakami, S., Nishiwaki, S., Miwa, J., Taketo, A., and Kodaira, K.-I. (1992)J. Neurochem. 58, 1517–1525), the function ofunc-64 remains unclear. Here we describe the cloning, and the molecular and genetic characterization of the unc-64gene, especially in relation to unc-18. unc-64 encodes a protein (C. elegans syntaxin) showing sequence and structural similarities to mammalian syntaxin 1A. Fromunc-64, at least three types of poly(A)+ RNA are transcribed, which encode two types of syntaxin that differ in the deduced transmembrane domain. In gene expression, unc-64closely resembles unc-18, that is, both are expressed in neural cells, especially in motor neurons and neurons constituting head ganglions. C. elegans syntaxin binds to UNC-18 with high affinity. The unc-64 (e246) mutation producing a mild phenotype causes an Ala → Val conversion in the conserved COOH-terminal region in mammalian syntaxin 1A or Drosophilasyntaxin-1A whose site is included in three types of transcripts. The binding of the mutant C. elegans syntaxin to UNC-18 is greatly reduced, indicating the mutation site contributes to the binding.
Footnotes
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↵* This study was supported in part by a Grant-in-Aid for Scientific Research from the NEC Corp. from the Ministry of Education, Science and Culture of Japan and from “Research for the Future” Program of the Japan Society for the Promotion (RFTR) of Science (to R. H.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) AB008842, AB008843, and AB008844.
The C. elegans syntaxin family (SYN1, SYN2, SYN3, and SYN4) discussed in this paper has been submitted to the SwissProt Data Bank with accession number(s) Q20024, Q20574, Q20797, and P91409.
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↵§ These authors contributed equally to this work.
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↵‡ To whom correspondence should be addressed: Dept. of Physical Information, Faculty of Medicine, 13-1 Takara-machi, Kanazawa University, Kanazawa, Ishikawa 920, Japan. Tel.: 81-76-265-2183; Fax: 81-762-34-4202; E-mail: rhosono{at}kenroku.ipc.kanazawa-u.ac.jp.
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↵1 The abbreviation used are: NSF,N-ethylmaleimide-sensitive factor; SNAP, solubleN-ethylmaleimide-sensitive factor attachment protein; v-SNARE, vesicle-associated soluble NSF attachment protein-SNAP receptor; SNAP-25, synaptosomal associated protein of 25 kDa; t-SNAREs, target membrane-associated SNAP receptors; ACh, acetylcholine; GST, glutathione S-transferase; YAC, yeast artificial chromosome; RT, reverse transcriptase; PCR, polymerase chain reaction; LG, linkage group; bp, base pair(s); kb, kilobase pair(s).
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↵2 S. Harada and R. Hosono, unpublished results.
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↵3 A. Fire, S. Xu, J. Ahnn, and G. Seydoux, personal communication.
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↵4 T. Ishihara, personal communication.
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- Received September 16, 1997.
- Revision received November 4, 1997.
- The American Society for Biochemistry and Molecular Biology, Inc.
