Site-specific and compensatory mutations imply unexpected pathways for proton delivery to the Q[sub B] binding site of the photosynthetic reaction center
- Argonne National Laboratory, IL (United States)
In photosynthetic reaction centers, a quinone molecule, Q[sub B], is the terminal acceptor in light-induced electron transfer. The protonatable residues Glu-L212 and Asp-L213 have been implicated in the binding of Q[sub B] and in proton transfer to Q[sub B] anions generated by electron transfer from the primary quinone Q[sub A]. Here the authors report the details of the construction of the Ala-L212/Ala-L213 double mutant strain by site-specific mutagenesis and show that its photosynthetic incompetence is due to an inability to deliver protons to the Q[sub B] anions. They also report the isolation and biophysical characterization of a collection of revertant and suppressor strains that have regained the photosynthetic phenotype. The compensatory mutations that restore function are diverse and show that neither Glu-L212 nor Asp-L213 is essential for efficient light-induced electron or proton transfer in Rhodobacter capsulatus. 42 refs., 3 figs., 1 tab.
- OSTI ID:
- 5295753
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America; (United States), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (United States) Vol. 90:19; ISSN PNASA6; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
CHARGED-PARTICLE TRANSPORT
CHEMICAL REACTIONS
GENE MUTATIONS
MEMBRANE PROTEINS
MUTATIONS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHETIC REACTION CENTERS
PROTEINS
PROTON TRANSPORT
RADIATION TRANSPORT
STRUCTURE-ACTIVITY RELATIONSHIPS