Schwarz B, Rochaix JD, Strasser RJ. The herbicide-resistant D1 mutant L275F of Chlamydomonas reinhardtii fails to show the bicarbonate-reversible formate effect on chlorophyll a fluorescence transients.
PHOTOSYNTHESIS RESEARCH 1991;
27:199-208. [PMID:
24414692 DOI:
10.1007/bf00035841]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/1990] [Accepted: 12/21/1990] [Indexed: 06/03/2023]
Abstract
Herbicide-resistant mutants of the eukaryotic green alga Chlamydomonas reinhardtii, that are altered in specific amino acids in their D-1 protein, show differential bicarbonate-reversible formate effects. These results suggest the involvement of D1 protein in the 'bicarbonate effect'. A 25 mM formate treatment of mixotrophically or photoautotrophically grown wild type cells results in a slower rise of chlorophyll a fluorescence transient followed by a dramatically slowed decline during measurements in continuous light. These effects are fully reversed upon addition of 10 mM bicarbonate. The mutant BR-202 [L275F] is, however, highly insensitive to 25 mM formate suggesting that a significant change in formate (bicarbonate) binding has occurred in helix V of the D1 protein near histidine involved in Fe binding. With the exception of DCMU-4 [S264A], which is considerably more sensitive to formate than the wild type, five other different [V219I, A25IV, F255Y, G256D and cell-wall deficient CW-15] mutants display a relatively similar response to formate as wild type. Absence of formate effect on a PS II-lacking [FuD-7] mutant confirms the sole involvement of PS II in the 'bicarbonate effect'.
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