Glyceraldehyde-3-phosphate dehydrogenase phylogeny supports an independent origin of the dinoflagellate chloroplast
Fagan, T.1, Hastings, J.W.1, Morse, D.2
1Dept of Molecular & Cellular Biology, Harvard University, 16 Divinity Ave.,
Cambridge, MA 02138, USA
2Dept of Biology, Universite de Montreal, 4101 Sherbrooke E., Montreal, HIX 2B2, Canada
Nuclear genes encoding cytoplasmic and chloroplastic forms of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) have been isolated from the dinoflagellate Gonyaulax polyedra. The two forms share 49% sequence identity at the amino acid level, and possess residues distinguishing them as having specificities for NAD+ and NAD+/NADP+, associated with the cytoplasmic and chloroplastic forms of the enzyme, respectively. The choroplastic form is also
characterized by the presence of an ~80 amino acid N-terminal extension, as is found in other plastid GAPDHs. Phylogenetic analyses place the plastid sequences well apart from the plastid GAPDHs of higher plants, chlorophytes and rhodophytes, suggesting that the dinoflagellate chloroplast may be derived from a distinct endosymbiotic event. This interpretation is consistent with other unusual features of the dinoflagellate chloroplast, including a triple bounding membrane, the presence of an unusual form II RuBisCo and peridinin, a carotenoid unique to dinoflagellates.
Morse, D., Salois, P., Marcovic, P. and Hastings, J.W. (1995) A nuclear-encoded form II RuBisCo in dinoflagellates. Science 268: 1622-1625.
Li, L., Hong, R. and Hastings, J. W. (1997) Three functional luciferase domains in a single polypeptide chain. Proc. Natl. Acad. Sci. 94: 8954-8958.
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Sunday, April 5 |
05:10 pm |