The Drosophila cinnamon gene is functionally homologous to Arabidopsis cnx1 and has a similar expression pattern to the mammalian gephyrin gene.
Molybdoenzymes are involved in a variety of essential pathways including nitrate assimilation, sulfur and/or purine metabolism and abscisic acid biosynthesis. Most organisms produce several such enzymes requiring a molybdopterin cofactor for catalytic function. Mutations that result in a lack of the molybdopterin cofactor display a pleiotropic loss of molybdoenzyme activities, and this phenotype has been used to identify genes involved in cofactor biosynthesis or utilization. Although several cofactor genes have been analyzed in prokaryotes, much less is known concerning eukaryotic molybdenum cofactor (MoCF) genes. This work is focused on the Drosophila MoCF gene cinnamon (cin) which encodes a multidomain protein, CIN, that shows significant similarity to three proteins encoded by separate prokaryotic MoCF genes. These domains are also present in the product of cnx1, an Arabidopsis MoCF gene, and in GEPHYRIN, a rat protein thought to organize the glycine receptor, GlyR, within the postsynaptic membrane. Since this apparent consolidation of separate prokaryotic genes into a single eukaryotic gene is a feature of other conserved metabolic pathways, we wished to determine whether the protein's function is also conserved. This report shows that the plant gene cnx1 can rescue both enzymatic and physiological defects of Drosophila carrying cin mutations, indicating that the two genes serve similar or identical functions. In addition, we have investigated the relationship between CINNAMON and GEPHYRIN, using immunohistochemical methods to localize the CIN protein in Drosophila embryos. Most of the CIN protein, like GEPHYRIN in the rat CNS, is localized to the cell borders and shows a tissue-specific pattern of expression. In a parallel study, antibody to GEPHYRIN revealed the same tissue-specific expression pattern in fly embryos. Both antibodies show altered staining patterns in cin mutants. Taken together, these results suggest that GEPHYRIN may also carry out a MoCF-related function.
Department of Biology, Emory University, Atlanta, GA 30322, USA.
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Wittle
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Kamdar
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Finnerty
D042931:Aldehyde Oxidase; D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017360:Arabidopsis / Q000235:genetics*; D002135:Calcium-Binding Proteins / Q000235:genetics*; D037281:Calnexin; D002352:Carrier Proteins / Q000235:genetics*; D002460:Cell Line; D004330:Drosophila / Q000196:embryology / Q000235:genetics*; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian / Q000502:physiology; D005260:Female; D018507:Gene Expression Regulation, Developmental; D007248:Infertility, Male / Q000235:genetics; D008297:Male; D008322:Mammals; D008562:Membrane Glycoproteins / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D008667:Metalloproteins / Q000235:genetics*; D008982:Molybdenum / Q000378:metabolism; D011401:Promoter Regions, Genetic; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis; D014162:Transfection
D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; C094757:Cnx1 protein, S pombe; D029721:Drosophila Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D008667:Metalloproteins; D011994:Recombinant Proteins; C089446:cin protein, Drosophila; C073441:gephyrin; D037281:Calnexin; D008982:Molybdenum; D000445:Aldehyde Oxidoreductases; D042931:Aldehyde Oxidase