Mutant Chlamydomonas

T. Flynn, ML. Ghirardi, M. Seibert (1999) Isolation of Chlamydomonas mutants with improved oxygen-tolerance. In Division of Fuel Chemistry Preprints of Symposia, 218th ACS National Meeting, 44 846-850... 

Starch is formed in chloroplasts of moss, fern and green algae.18 Chlorophyceae (green algae) starch is similar to that of higher plants, and several species have been used in studies of starch biosynthesis.19,22,29 In a recent set of studies, Ball et al.22 used Chlamydomonas reinhardtii to study starch biosynthesis. They produced several Chlamydomonas mutants which produce starch with characteristics similar to starches produced by maize endosperm mutants.31-34 The various starch mutations of Chlamydomonas will be discussed in Section 3.7. Other classes of algae which produce starch are Prasinophyceae19,35 and Cryptophyceae.35,36... 

These studies, using Chlamydomonas mutants, provide evidence for the involvement of the GBSS, not only in amylose, but also in amylopectin synthesis, and suggest that a function for SSSII is in the synthesis of the intermediate size B-branch chains in amylopectin. 

Chlamydomonas mutants that are entirely deficient in colored carotenoids do not accumulate reaction centers or light-harvesting complexes of Photosystem I or Photosystem II (Herrin et al., 1992). The accumulation of the mRNAs does not seem to be affected, so the failure in protein accumulation must be either due to inhibition of translation or rapid degradation of the proteins that cannot be assembled in the absence of carotenoids. Chi is also synthesized but very rapidly degraded in these mutants. 

Mutants of Scenedesmus obliquus have been desaibed that are carotenoid-deficient when grown in the dark because of a lack of phytoene synthase activity (Sandmaim et al, 1997). These mutants behave differently from the Chlamydomonas mutants in that they assemble a functional PS I but no PS II and no Chi a/b complexes (Humbeck et al., 1989 Romer et al., 1995). Upon illumination, carotenoids are formed and, concomitantly, PS II activity and light-harvesting complexes appear (Romer et al.,... 

Chlamydomonas mutants have been isolated that are deficient either in violaxanthin de-epoxidase or zeaxanthin epoxidase. Using these mutants, it could be demonstrated that only part of the non-photochemical quenching observed in Chlamydomonas is dependent on the formation of zeaxanthin (Niyogi etal., 1997a). It will be interesting to see whether the absence of xanthophyll epoxidase or de-epoxidase products has an effect on the assembly of light-harvesting complexes in these mutants. 

To further analyze the effect of impaiied pigment synthesis in Chlamydomonas, a double mutant was prepared by crossing npql with lorl, a Chlamydomonas mutant defective in the synthesis of a-carotene, lutein andloroxanthin (Niyogi etal., 1997b). 

SPECIFIC LOSS OF LHCII PHOSPHORYLATION IN A CHLAMYDOMONAS MUTANT LACKING THE CYTOCHROME hjf COMPLEX... 

Recent studies in our laboratory have indicated that the cytochrome hjf cyVhJT) complex is involved in the light induced phosphorylation of LHQI polypeptides in Acetabularia mdLemna (1,2). Similar data have been obtained with several cyt.be/f deficient Chlamydomonas (3) and maize mutants (4,5). To furtho ascertain that indeed the cyth /f complex is required for the activation of the redox controlled LHC n kinase, the activity of this enzyme(s) was assayed in another Chlamydomonas mutant lacking the complex components. 

Specific Loss of LCHII Phosphorylation in a Chlamydomonas Mutant Lacking the... 

Nakamura, S., Watanabe, M., Hatase, K., and Kojima, M.K., Light inhibits flagellation in a Chlamydomonas mutant. Plant Cell. Physiol, 31, 399M 01, 1990. 

Sineshchekov, O.A., Govorunova, E.G., Der, A., Keszthelyi, L., and Nultsch, W., Photoinduced electric currents in carotenoid-dehcient Chlamydomonas mutants reconstituted with retinal and its analogs, Biophys.., 66, 6, 2073, 1994. 

The biflagellate unicellular green alga Chlamydomonas reinhardtii is prone to spontaneous mutations that produce deficiencies in flagellar proteins and MT assembly, substructure, and function. Viable mutants that are either nonmotile or slow moving can be isolated and analyzed biochemically and morphologically, thereby establishing structure-function correlations. Electron microscopic analysis... 

Holub, O., Seufferheld, M. J., Gohlke, C., Govindjee, G. J., Heiss, G. J. and Clegg, R. M. (2007). Fluorescence lifetime imaging microscopy of Chlamydomonas reinhardtii Non-photochemical quenching mutants and the effect of photosynthetic inhibitors on the slow chlorophyll fluorescence transients. J. Microsc. 226, 90-120. 

D. Hahn, P. Bennoun, U. Kiick (1996) Altered expression of nuclear genes encoding thechloroplast polypeptides in non-photosynthetic mutants of Chlamydomonas... 

PS1 The PS 1-prep, introduced in this communication is the first reported with a polyhistidine tag fused to the N-terminus of the PsaF subunit. This construct was possible due to the fact that cyanobacterial PsaF-deletion mutants show no impact on photoautotrophic growth - in contrast to Chlamydomonas reinhardtii, where inactivation of PsaF results in a severe reduction of electron transfer from plastocyanin to PS 1 [Hippier et al. 1997], Also, the N-terminus of the F-subunit which was decorated by the tag is located towards the lumen side which enables an attachment of the isolated PS1 with the lumen-exposed /donor-side to the electrode surface in our hydrogen-producing device. 

White, A.L., Melis, A. 2006. Biochemistry of hydrogen metabolism in Chlamydomonas rein-hardtii wild type and a Rubisko-less mutant. Int J Hydrogen Energy 31 455 65. 

In spite of these limitations to our complete knowledge of starch biosynthesis, information about the pathway of starch biosynthesis gained from studies of maize endosperm mutants can probably be generalized to other plant species because related mutants have occurred in peas, sorghum, barley, rice and Chlamydomonas, and because the same enzymes are found in starch-synthesizing tissues in other plant species. Variation in the number of isozymes and their developmental expression, and variations in cellular compartmentation, however, could result in a range of pathways with significant differences. 

A mutant of starch synthase II has also been isolated in Chlamydomonas rein-hardtii 193 this mutant, st-3, accumulated only 20-40% of the amount of starch present in the wild type. The enzyme lacking in the mutant was starch synthase II, one of the two starch synthase isoforms present in C. reinhardlii.m There was an apparent increase in the amylose content, and in a modified form of amylopectin. The changes noted in the mutant amylopectin were a decrease in the number of intermediate-size chains (DP 8-50) and an increase in short chains (DP 2-7). The conclusion made was that this starch synthase II was responsible for synthesis of intermediate-size... 

Some starch-deficient mutants of Arabidopsis and Chlamydomonas have been shown to be defective in a-l,4-glucanotransferase activity. The enzyme is also known as D-enzyme. The reaction it catalyzes is as follows ... 

Photosystem II reaction centres have been shown to be located mainly in the appressed granal membranes by a number of independent but indirect methods, including thylakoid fractionation, de-stacking and re-stacking experiments and chemical modification. Further evidence has come from freeze-fracture investigations of mutants specifically deficient in photosystem II in barley (Simpson et al., 1977), tobacco (Miller and Cushman, 1979) and Chlamydomonas (Olive etal. 1979). In all cases, there was a partial or almost... 

Olive, J., Wollman, F.A., Bennoun, P. and Recouvreur, M. 1979. Ultrastruct-ure—function relationship in Chlamydomonas reinhardtii thylakoids, by means of a comparison between the wild type and the F34 mutant which lack the photosystem II reaction center. Molec. Biol. Rep. 5,139-143. 

Ball, S., Marianne, T., Dirick, L., Fresnoy, M., Delrue, B., and Decq, A. 1991. A Chlamydomonas reinhardtii low-starch mutant is defective for 3-phosphoglycerate activation and orthophosphate inhibition of ADP-glucose pyrophosphorylase. Planta 185,17-26. 

Delrue, B., Fontaine, T., Routier, F., Decq. A., Wieruszeski, J.-M., Van Den Koomhuyse, N., Maddelein, M.-L., Fournet, B., and Ball, S. 1992. Waxy Chlamydomonas reinhardtii Monocellular algal mutants defective in amylose synthesis and granule-bound starch synthase activity accumulate a structurally modified amylopectin. J. BacterioL 174,3612-3620. 

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