Carotenoids of Wild Type and Mutant Strains of the Green Aiga, <i>Chlamydomonas reinhardi</i>

Krinsky, Norman I.; Levine, R. P.

doi:10.1104/pp.39.4.680

Cited by 55 publications

(19 citation statements)

References 18 publications

(23 reference statements)

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“…Pigment content of wild type and transformants was determined according to Krinsky and Levine (1964) with the correction of Francis et al . (1973).…”

Section: Methodsmentioning

confidence: 99%

Disruption of the plastid ycf10 open reading frame affects uptake of inorganic carbon in the chloroplast of Chlamydomonas

Rolland¹

1997

The EMBO Journal

110

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The product of the chloroplast ycf10 gene has been localized in the inner chloroplast envelope membrane (Sasaki et al., 1993) and found to display sequence homology with the cyanobacterial CotA product which is altered in mutants defective in CO 2 transport and proton extrusion (Katoh et al., 1996a,b). In Chlamydomonas reinhardtii, ycf10, located between the psbI and atpH genes, encodes a putative hydrophobic protein of 500 residues, which is considerably larger than its higher plant homologue because of a long insertion that separates the conserved N and C termini. Using biolistic transformation, we have disrupted ycf10 with the chloroplast aadA expression cassette and examined the phenotype of the homoplasmic transformants. These were found to grow both photoheterotrophically and photoautotrophically under low light, thereby revealing that the Ycf10 product is not essential for the photosynthetic reactions. However, under high light these transformants did not grow photoautotrophically and barely photoheterotrophically. The increased light sensitivity of the transformants appears to result from a limitation in photochemical energy utilization and/or dissipation which correlates with a greatly diminished photosynthetic response to exogenous (CO 2 ⍣ HCO 3 -), especially under conditions where the chloroplast inorganic carbon transport system is not induced. Mass spectrometric measurements with either whole cells or isolated chloroplasts from the transformants revealed that the CO 2 and HCO 3 -uptake systems have a reduced affinity for their substrates. The results suggest the existence of a ycf10-dependent system within the plastid envelope which promotes efficient inorganic carbon (Ci) uptake into chloroplasts.

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“…Pigment content of wild type and transformants was determined according to Krinsky and Levine (1964) with the correction of Francis et al . (1973).…”

Section: Methodsmentioning

confidence: 99%

Disruption of the plastid ycf10 open reading frame affects uptake of inorganic carbon in the chloroplast of Chlamydomonas

Rolland¹

1997

The EMBO Journal

110

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“…The normal dark pathway for carotene synthesis is inactive in strain FN68, making it easier to study the light regulation of the carotene and retinal synthesis pathway (11,12 We found that phototactic sensitivity was linearly related to the concentration of exogenously supplied chromophore (at least for low concentrations). Since the amount of retinal or retinol incorporated probably depends linearly on its concentration in solution, the observed sensitivity must be directly proportional to the concentration of pigment.…”

Section: Discussionmentioning

confidence: 83%

Autoregulation of rhodopsin synthesis in Chlamydomonas reinhardtii.

Foster

Saranak

Zarrilli

1988

Proc. Natl. Acad. Sci. U.S.A.

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A sensitive assay for the induction of carotenoid and rhodopsin synthesis, based on the phototactic response, has been developed in a mutant of the unicellular alga Chlamydomonas reinhardtii. In the dark, the mutant fails to synthesize carotene and retinal, but it contains the apoprotein opsin. When retinal synthesis is induced by light treatment, the retinal combines with opsin to form rhodopsin, and the cells swim away from a source of light. Since the amount of light required to trigger a phototactic response is inversely proportional to the concentration of rhodopsin, the decrease in amount of light necessary to generate that response can serve as a measure of the amount of retinal synthesized in cells after induction. Using this assay, we found that (i) light induction of retinal depends linearly on light exposure and rhodopsin concentration during the exposure; (ii) the action spectrum of light induction is identical with that for phototaxis for which the receptor pigment is rhodopsin; and (iii) incubation with alltrans-7,8-dihydroretinal before light exposure shifts the actionspectrum peak for light induction 0.41 eV (-71 nm). We conclude that the photopigment for induction of retinal synthesis is a rhodopsin. The time lag required for induction of retinal synthesis and preliminary experiments with transcription or translation inhibitors suggest that alterations in gene expression could be involved in the induction process. Its control could be similar to other processes in which membrane receptors for hormones, neurotransmitters, or growth factors regulate gene expression.Rhodopsin plays multiple roles in animals. It is the photoreceptor for vision and a regulator of circadian rhythm and melatonin production. In vertebrates, it acts as a regulator both in the pineal gland (1) and, to a lesser extent, in the retinal photoreceptor cells (2). In Chlamydomonas, a flagellated eukaryotic alga, we found that a bovine-like rhodopsin serves as the photoreceptor pigment for phototaxis (3). Rhodopsin in eukaryotes is thus of ancient origin. Analysis of 5S RNAs (4) has shown that the Chlamydomonas evolutionary line branched from the plant line soon after the plant and animal lines diverged. The question naturally arises whether the regulatory function of rhodopsin is also ancient.The identity of the light receptors that regulate carotene synthesis in bacteria, fungi, algae, and angiosperms has been uncertain. Flavoproteins, porphyrins, and carotenoid proteins have all been suggested on the basis of action spectra in various organisms (5).The measurement of phototaxis threshold (3) has given us a sensitive assay for the presence of rhodopsin. We noticed that carotenoid mutants exposed to light recovered their phototaxis. Here we report that rhodopsin excitation induces synthesis of carotene and retinal. We do not know the nature of the induced products or how they modulate the synthetic pathway. Nevertheless, since retinal, the chromophore for rhodopsin, is synthesized as a result of rhodopsin excitation, we ...

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“…The initial molar ratio of total carotenoids to chlorophyll is about 1 .1 as compared with about 0 .2 in light-grown cells (0 .23 in isolated spinach chloroplast lamellae [21]) . Other carotenoids which were reported to be present in the wild type Chlamydomonas reinhardi, such as a-carotene, luteoxanthin, zeaxanthin, and trollein (24), were probably present in y-1 cells in amounts too small to be detected on the chromatograms .…”

Section: Method the Incorporation Of Acetate-3h Into Thementioning

confidence: 92%

Biogenesis of Chloroplast Membranes

Goldberg

Ohad

1970

The Journal of Cell Biology

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The glycolipid, phospholipid, pigment, and fatty acid content in whole y-1 cells during the greening process have been investigated . The time course of their changes indicates that phosphatidyl glycerol and glycolipids are the main lipids synthesized specifically during illumination of dark-grown cells, concomitant with an increase in the polyunsaturated C18 :2 and C18 :3 fatty acids . The pigment complex of light-grown cells consists mainly of chlorophylls a and b, lutein, 0-carotene, violaxanthin, and neoxanthin . During the greening process, chlorophylls a and b are synthesized in constant proportions (ratio a/b equals 2 .6), 0-carotene and violaxanthin do not change significantly, and lutein and neoxanthin increase . The molar ratios of the different lipids and pigment to total chlorophyll during greening has been calculated . It was found that during the initial phase of greening when chlorophyll is synthesized at increasing rates, the molar ratios of various lipids and pigments to chlorophyll decrease and tend to become constant when chlorophyll and membrane synthesis proceed at constant rates . The implication of these findings with respect to the concept of membrane assembly through a spontaneous single step process is discussed INTRODUCTION

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Carotenoids of Wild Type and Mutant Strains of the Green Aiga, Chlamydomonas reinhardi

Cited by 55 publications

References 18 publications

Disruption of the plastid ycf10 open reading frame affects uptake of inorganic carbon in the chloroplast of Chlamydomonas

Disruption of the plastid ycf10 open reading frame affects uptake of inorganic carbon in the chloroplast of Chlamydomonas

Autoregulation of rhodopsin synthesis in Chlamydomonas reinhardtii.

Biogenesis of Chloroplast Membranes

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