Abstract
Several lines of evidence indicate that allophycocyanin is the previously unidentified “phycochrome” observed in extracts of blue-green algae.
Fractions containing phycoerythrin, phycocyanin, and allophycocyanin and exhibiting light-induced absorbance changes were prepared from extracts of Nostoc muscorum and Fremyella diplosiphon by isoelectric focusing. Illumination of such fractions with red light (650 nanometers) causes a reduction in absorbance at 620 nm (≃1 to 2%) and an increase at 560 nm. The effect, (previously observed by Björn and Björn [1976 Physiol Plant 36: 297-304]) is reversible, upon illumination with green light (550 nm). Selective immunoprecipitation of the phycobiliproteins indicates that allophycocyanin is the photoresponsive pigment.
At pH 4.0 to 4.2, allophycocyanin purified from the same algae or from Phormidium luridum exhibits a light-induced absorbance change at 620 nm, which coincides with its absorption maximum at this pH; the fluorescence emission of allophycocyanin under these conditions is at 647 nm and its S20,w is 2.28, compatible with an α1β1 polypeptide composition. At neutral pH (5.8 to 7.0), allophycocyanin aggregates have a sedimentation coefficient of 4.8 (≃α3β3) and an additional absorption peak at 640 nm appears while that at 620 nm remains unaffected. The fluorescence emission maximum of the larger aggregate is at 667 nm and the light-induced change in its absorption is shifted to 650 nm. The effect of pH changes in the range 4.0 to 7.0 on the spectral and aggregation properties of allophycocyanin is completely reversible. Changes in pH which affect allophycocyanin aggregation have parallel effects on absorption and fluorescence maxima as well as on the light-induced absorbance changes of the biliprotein.
No evidence is provided to resolve whether this phycochrome plays the role of an adaptochrome.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bennett A., Bogorad L. Complementary chromatic adaptation in a filamentous blue-green alga. J Cell Biol. 1973 Aug;58(2):419–435. doi: 10.1083/jcb.58.2.419. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Diakoff S., Scheibe J. Action Spectra for Chromatic Adaptation in Tolypothrix tenuis. Plant Physiol. 1973 Feb;51(2):382–385. doi: 10.1104/pp.51.2.382. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Glazer A. N., Bryant D. A. Allophycocyanin B (lambdamax 671, 618 nm): a new cyanobacterial phycobiliprotein. Arch Microbiol. 1975 Jun 20;104(1):15–22. doi: 10.1007/BF00447294. [DOI] [PubMed] [Google Scholar]
- Gysi J., Zuber H. Allophycocyanin I-a second cyanobacterial allophycocyanin? Isolation, characterization and comparison with allophycocyanin II from the same alga. FEBS Lett. 1976 Sep 15;68(1):49–54. doi: 10.1016/0014-5793(76)80402-4. [DOI] [PubMed] [Google Scholar]
- Gysi J., Zuber H. Isolation and characterization of allophycocyanin II from the thermophilic blue-green alga Mastigocladus laminosus Cohn. FEBS Lett. 1974 Nov 15;48(2):209–213. doi: 10.1016/0014-5793(74)80469-2. [DOI] [PubMed] [Google Scholar]
- Haury J. F., Bogorad L. Action Spectra for Phycobiliprotein Synthesis in a Chromatically Adapting Cyanophyte, Fremyella diplosiphon. Plant Physiol. 1977 Dec;60(6):835–839. doi: 10.1104/pp.60.6.835. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ley A. C., Butler W. L. Isolation and Function of Allophycocyanin B of Porphyridium cruentum. Plant Physiol. 1977 May;59(5):974–980. doi: 10.1104/pp.59.5.974. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Scheibe J. Photoreversible pigment: occurrence in a blue-green alga. Science. 1972 Jun 2;176(4038):1037–1039. doi: 10.1126/science.176.4038.1037. [DOI] [PubMed] [Google Scholar]