Replacement of histidine by glutamine at select residues in the chlorophyll-binding protein CP47 in photosystem II. [Synechocystis sp. PCC 6803]
- Arizona State Univ., Tempe (United States)
A mutant strain of the cyanobacterium Synechocystis sp. PCC 6803 has been developed in which psbB, the gene coding for the chlorophyll a-binding protein CP47 in photosystem II (PS II), has been deleted. This deletion mutant has been used for the reintroduction of modified psbB into the cyanobacterium. Histidine residues in hydrophobic regions of CP47 are potential ligands to chlorophyll molecules. Three histidine residues in the putative sixth membrane spanning helix of this protein have been replaced by glutamine, resulting in mutants H455Q, H466Q and H469Q (the number refers to the CP47 residue that was altered). Both H455Q and H466Q are able to grow photoautotrophically with a doubling time of 12 hours at a rate similar to wild type. H469Q, however, has a doubling time of 50 hours. The chlorophyll/PS II ratio in H469Q is also increased from 600 (as found in wild type, H455Q and H466Q) to 3,300. The 695 nm 77K fluorescence emission, emanating from PS II, is also greatly reduced in H469Q. They conclude that histidine 469 is required for the stable incorporation of CP47 into the thylakoid membrane and is therefore required for the stable assembly of the PS II reaction center.
- DOE Contract Number:
- FG02-89ER14031
- OSTI ID:
- 5401783
- Report Number(s):
- CONF-9107184--
- Journal Information:
- Plant Physiology, Supplement; (United States), Journal Name: Plant Physiology, Supplement; (United States) Vol. 96:1; ISSN PPYSA; ISSN 0079-2241
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AMIDES
AMINO ACIDS
AZOLES
CARBOXYLIC ACIDS
CHLOROPHYLL-BINDING PROTEINS
CYANOBACTERIA
GENES
GLUTAMINE
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HISTIDINE
IMIDAZOLES
MICROORGANISMS
MOLECULAR STRUCTURE
MUTANTS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOSYNTHETIC REACTION CENTERS
PHYSIOLOGY
PROTEINS