Calcium regulates the expression of a Dictyostelium discoideum asparaginyl tRNA synthetase gene.
In a screen for calcium-regulated gene expression during growth and development of Dictyostelium discoideum we have identified an asparaginyl tRNA synthetase (ddAsnRS) gene, the second tRNA synthetase gene identified in this organism. The ddAsnRS gene shows many unique features. One, it is repressed by lowering cellular calcium, making it the first known calcium-regulated tRNA synthetase. Two, despite the calcium-dependence, its expression is unaltered during the cell cycle, making this the first D. discoideum gene to show a calcium-dependent but cell cycle phase-independent expression. Finally, the N-terminal domain of the predicted ddAsnRS protein shows higher sequence similarity to Glutaminyl tRNA synthetases than to other Asn tRNA synthetases. These unique features of the AsnRS from this primitive eukaryote not only point to a novel mechanism regulating the components of translation machinery and gene expression by calcium, but also hint at a link between the evolution of GlnRS and AsnRS in eukaryotes.
Jaiswal
Jyoti K
JK
Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India. jaiswaj@mail.rockefeller.edu
Nanjundiah
Vidyanand
V
D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry / Q000235:genetics*; D000818:Animals; D001226:Aspartate-tRNA Ligase; D001483:Base Sequence; D002118:Calcium / Q000502:physiology*; D018076:DNA, Complementary; D004023:Dictyostelium / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012346:RNA, Transfer, Amino Acyl; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D018076:DNA, Complementary; D012346:RNA, Transfer, Amino Acyl; D000604:Amino Acyl-tRNA Synthetases; D001226:Aspartate-tRNA Ligase; C029194:asparaginyl-tRNA synthetase; D002118:Calcium