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Caenorhabditis elegans contains two distinct acid sphingomyelinases.


Lin, X; Hengartner, M O; Kolesnick, R N (1998). Caenorhabditis elegans contains two distinct acid sphingomyelinases. Journal of Biological Chemistry, 273(23):14374-14379.

Abstract

Mounting evidence supports a role for acid sphingomyelinase (ASM) in cellular stress signaling. Only murine and human sphingomyelinases have been defined at the molecular level. These enzymes are the products of a conserved gene and at the amino acid level share 82% identity. In this study, we show that the nematode Caenorhabditis elegans possesses two ASMs, termed ASM-1 and ASM-2 encoded by two distinct genes, but lacks detectable neutral sphingomyelinase activity. The C. elegans ASMs are about 30% identical with each other and with the human and murine enzymes. The conserved regions include a saposin-like domain, proline-rich domain, and a putative signal peptide. In addition, 16 cysteines distributed throughout the molecules, and selected glycosylation sites, are conserved. The expression of these genes in C. elegans is regulated during development. Asm-1 is preferentially expressed in the embryo, whereas asm-2 is predominantly expressed in postembryonic stages. When transfected as Flag-tagged proteins into COS-7 cells, ASM-1 is found almost entirely in a secreted form whereas only 20% of ASM-2 is secreted. Only the secreted forms display enzymatic activity. Furthermore, ASM-2 requires addition of Zn2+ to be fully active, whereas ASM-1 is active in the absence of cation. C. elegans is the first organism to display two ASMs. This finding suggests the existence of an ASM gene family.

Mounting evidence supports a role for acid sphingomyelinase (ASM) in cellular stress signaling. Only murine and human sphingomyelinases have been defined at the molecular level. These enzymes are the products of a conserved gene and at the amino acid level share 82% identity. In this study, we show that the nematode Caenorhabditis elegans possesses two ASMs, termed ASM-1 and ASM-2 encoded by two distinct genes, but lacks detectable neutral sphingomyelinase activity. The C. elegans ASMs are about 30% identical with each other and with the human and murine enzymes. The conserved regions include a saposin-like domain, proline-rich domain, and a putative signal peptide. In addition, 16 cysteines distributed throughout the molecules, and selected glycosylation sites, are conserved. The expression of these genes in C. elegans is regulated during development. Asm-1 is preferentially expressed in the embryo, whereas asm-2 is predominantly expressed in postembryonic stages. When transfected as Flag-tagged proteins into COS-7 cells, ASM-1 is found almost entirely in a secreted form whereas only 20% of ASM-2 is secreted. Only the secreted forms display enzymatic activity. Furthermore, ASM-2 requires addition of Zn2+ to be fully active, whereas ASM-1 is active in the absence of cation. C. elegans is the first organism to display two ASMs. This finding suggests the existence of an ASM gene family.

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Additional indexing

Item Type:Journal Article, refereed
Communities & Collections:07 Faculty of Science > Institute of Molecular Life Sciences
Dewey Decimal Classification:570 Life sciences; biology
Language:English
Date:5 June 1998
Deposited On:11 Feb 2008 12:19
Last Modified:26 Aug 2016 07:32
Publisher:American Society for Biochemistry and Molecular Biology
ISSN:0021-9258
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:10.1074/jbc.273.23.14374
Related URLs:http://www.jbc.org/cgi/content/abstract/273/23/14374
PubMed ID:9603947
Permanent URL: http://doi.org/10.5167/uzh-956

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