Dictyostelium discoideum has a single diacylglycerol kinase gene with similarity to mammalian theta isoforms.
Diacylglycerol kinases (DGKs) phosphorylate the neutral lipid diacylglycerol (DG) to produce phosphatidic acid (PA). In mammalian systems DGKs are a complex family of at least nine isoforms that are thought to participate in down-regulation of DG-based signalling pathways and perhaps activation of PA-stimulated signalling events. We report here that the simple protozoan amoeba Dictyostelium discoideum appears to contain a single gene encoding a DGK enzyme. This gene, dgkA, encodes a deduced protein that contains three C1-type cysteine-rich repeats, a DGK catalytic domain most closely related to the theta subtype of mammalian DGKs and a C-terminal segment containing a proline/glutamine-rich region and a large aspargine-repeat region. This gene corresponds to a previously reported myosin II heavy chain kinase designated myosin heavy chain-protein kinase C (MHC-PKC), but our analysis clearly demonstrates that this protein does not, as suggested by earlier data, contain a protein kinase catalytic domain. A FLAG-tagged version of DgkA expressed in Dictyostelium displayed robust DGK activity. Earlier studies indicating that disruption of this locus alters myosin II assembly levels in Dictyostelium raise the intriguing possibility that DG and/or PA metabolism may play a role in controlling myosin II assembly in this system.
De La Roche
Marc A
MA
Department of Biochemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Smith
Janet L
JL
Rico
Maribel
M
Carrasco
Silvia
S
Merida
Isabel
I
Licate
Lucila
L
Côté
Graham P
GP
Egelhoff
Thomas T
TT
D000465:Algorithms; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D020134:Catalytic Domain; D003001:Cloning, Molecular; D003545:Cysteine / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D019852:Diacylglycerol Kinase / Q000737:chemistry* / Q000235:genetics*; D004023:Dictyostelium; D015536:Down-Regulation; D006801:Humans; D008957:Models, Genetic; D008969:Molecular Sequence Data; D024462:Myosin Type II / Q000737:chemistry / Q000378:metabolism; D010712:Phosphatidic Acids / Q000378:metabolism; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D011485:Protein Binding; D020033:Protein Isoforms; D011493:Protein Kinase C / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D018076:DNA, Complementary; D010712:Phosphatidic Acids; D020033:Protein Isoforms; D012313:RNA; D019852:Diacylglycerol Kinase; D011493:Protein Kinase C; D024462:Myosin Type II; D003545:Cysteine