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Photochemical apparatus organization in Synechococcus 6301 (Anacystis nidulans). Effect of phycobilisome mutation (1984)

Manodori, A. ; Alhadeff, M. ; Glazer, A. N. ; [et al.]

Springer

Archives of microbiology 139 (1984), S. 117-123

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ISSN: 1432-072X

Keywords: Cyanobacteria (Synechococcus) ; Photochemical apparatus ; Photosystem ; Phycobilisome ; Excitation transfer ; Light-harvesting pigment ; Thylakoid membrane organization

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The photochemical apparatus organization in Synechococcus 6301 (Cyanophyceae) was investigated under various experimental conditions. Wild type (WT) Synechococcus produced phycobilisomes (PBSs) containing normal levels of phycocyanin (Phc) and allophycocyanin (Aphc). The ratio of reaction centers(RC) RCII/RCI of 0.4 was the same in WT and the mutant strain AN112, whereas RCH/PBS was 1.9:1 in WT and 1:1 in AN112. Excitation of WT cells with broad-band 620 nm light, which is absorbed primarily by Phc and Aphc and to a much lesser extent by chlorophyll (Chl), sensitized the RC of photosystem (PS) II at about 15 times the rate it sensitized RCI. This implies that PBSs are associated exclusively with PSII complexes and that PBS excitation is not transferred to PSI. The AN112 mutant of Synechococcus produced smaller PBSs consisting of the Aphc-containing core and of only six Phc-containing hexamers, respectively. It lacked about 65% of the Phccontaining rod substractures. Under our experimental conditions, the effective absorption cross section of the mutant PBS was only about half that of the WT. In agreement, the rate of RCII excitation by 620 nm light was also about half of that measured in the WT. Thus, the rate of light absorption by PSII depends directly on PBS size and composition. The low rate of RCI excitation with 620 nm light was the same in WT and AN112 cells, apparently independent of the PBS effective absorption cross section. We propose a strict structural-functional association between PBS and PSII complex. PSI is a structurally distinct entity and it receives excitation independently from its own Chl light-harvesting antenna.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00401985

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Core substructure in cyanobacterial phycobilisomes (1983)

Gingrich, Jeffrey C. ; Lundell, Daniel J. ; Glazer, Alexander N.

New York, N.Y. : Wiley-Blackwell

Journal of Cellular Biochemistry 22 (1983), S. 1-14

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ISSN: 0730-2312

Keywords: cyanobacteria ; phycobilisome substructure ; allophycocyanin complexes ; biliproteins ; energy transfer ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Chemistry and Pharmacology , Medicine

Notes: The tricylindrical core of Synechocystis 6701 phycobilisomes is made up of four types of allophycocyanin-containing complexes: A, (αAP βAP)3; B, (αAP βAP)3 .10K; C, (α1APBα2APβ3AP).10K; D, (αAP βAP)2.18.5K.99K; where AP is allophycocyanin, APB is allophycocyanin B, and 10K, 18.5K, and 99K are polypeptides of 10,000, 18,500, and 99,000 daltons, respectively. The 18.5K polypeptide is a hitherto unrecognized biliprotein subunit with a single phycocyanobilin prosthetic group. The tricylindrical core is made up of 12 subcomplexes in the molar ratio of A:B:C:D: of 4:4:2:2. Complexes C and D act as terminal energy acceptors. From these results and previous analysis of the bicylindrical core of Synechococcus 6301 phycobilisomes [14,15] it is proposed that the two cylinders of the Synechocystis 6701 core, proximal to the thylakoid membrane, each have the composition ABCD, and that the distal cylinder has the composition A2B2.

Additional Material: 8 Ill.