Construction of an obligate photoheterotrophic mutant of the cyanobacterium Synechocystis 6803: inactivation of the psbA gene family
psbA in Synechocystis 6803 was found to belong to a small multigene family with three copies. The psbA gene family was inactivated in vitro by insertion of bacterial drug resistance markers. Inactivation of all three genes resulted in a transformant that is unable to grow photosynthetically but can be cultured photoheterotrophically. This mutant lacks oxygen evolving capacity but retains photosystem I activity. Room temperature measurements of chlorophyll a fluorescence induction demonstrated that the transformant exhibits a high fluorescence yield with little or no variable fluorescence. Immunoblot analyses showed complete loss of the psbA gene product (the DI polypeptide) from thylakoid membranes in the transformant. However, the extrinsic 33 kilodalton polypeptide of the water-splitting complex of photosystem II, is still present. The results indicate that assembly of a partial photosystem II complex may occur even in the absence of the intrinsic D1 polypeptide, a protein implicated as a crucial component of the photosystem II reaction center.
- Research Organization:
- Michigan State Univ., East Lansing
- DOE Contract Number:
- AC02-76ER01338
- OSTI ID:
- 5563190
- Journal Information:
- Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 85:2; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL FUNCTIONS
CHEMICAL REACTIONS
CHLOROPHYLL-BINDING PROTEINS
CYANOBACTERIA
FLUORESCENCE
FUNCTIONS
GENE RECOMBINATION
GENES
KINETICS
LUMINESCENCE
MICROORGANISMS
MUTANTS
ORGANIC COMPOUNDS
PEPTIDES
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHOTOSYNTHETIC REACTION CENTERS
POLYPEPTIDES
PROTEINS
REACTION KINETICS
SYNTHESIS