Which of the following component from Halobacterium salinarum absorb the energy in sunlight and generates proton motive force (pmf) through phocycling under anaerobic or microaerobic conditions ?
MH SET - 2023, SET Exam - 2023,
Answer: C
The light-driven proton pump is Bacteriorhodopsin.
Under low oxygen, Halobacterium salinarum makes purple membrane patches packed with bacteriorhodopsin, a protein bound to retinal. Absorbing a photon isomerises retinal from all-trans to 13-cis, and the protein's photocycle (the paper's 'phocycling') moves one proton out of the cell per photon. The resulting proton motive force drives ATP synthase, a form of phototrophy without chlorophyll.
Chlorosomes are the light-harvesting antennae of green sulphur bacteria, bacteriochlorophyll a is the photosynthetic pigment of purple bacteria, and photosystem I belongs to cyanobacteria and plants. Halobacteria, which are archaea, have none of these.
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