| Chlamydomonas - a survivalist under anaerobic conditions |
| A. Hemschemeier, J. Jacobs, D. Kravietz, G. Philipps, T. Rühle and T. Happe |
| Ruhr Universität Bochum, Fakultät für Biologie und Biotechnologie, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, 44780 Bochum, Germany |
| While Chlamydomonas reinhardtii is a common model for studying processes in higher plants (1, 2), it has retained many of the genes from the common ancestor of both plants and animals (3), which has also made it a valuable model for studying animal-specific pathways such as the biology of cilia (4). But this organism, sometimes referred to as "half beast-half plant" (5), was also reported to have enzymes typically found in prokaryotes. It has two molecular hydrogen (H2) producing [FeFe]-hydrogenases HydA1 and HydA2. The biochemically characterized HydA1 protein is coupled to the photosynthetic electron transport chain (6). Furthermore, C. reinhardtii has a formate and ethanol producing fermentative metabolism, which was proposed to be initiated by pyruvate formate lyase (Pfl1). Both the hydrogen and the formate/ethanol producing pathways are involved in a sustained anaerobic metabolism of the alga, which can be induced by sulphur depletion in illuminated cultures (7). We have examined the bacteria-like putative Pfl1 protein of C. reinhardtii and proved the formate producing activity of the enzyme by heterologous expression of the algal PFL1 cDNA in Escherichia coli (8). A detailed analysis of the photofermentative pathways in sulphur-depleted algae gives new insights into the extraordinary flexibility of the algal anaerobic metabolism, which has characteristics of plant, mammal and bacterial pathways (8, 9).
1) Rochaix J.D. (2002) FEBS Lett 529, 34-38 |
| e-mail address of presenting author: anja.hemschemeier@rub.de |