Question

1. Bacteriorhodopsins and Proteorhodopsins may play an important role in sustaining bacteria and archaea in the world’s oceans. Give at least 1-2 paragraphs for each question.
   1. What is that role, and how was it determined?
   2. How widespread are organisms carrying genes for these pigments? Where are they found?
   3. Do these pigments provide an ecological advantage to the microbes that possess them?  What is the evidence?

Answer 1

a. The biological world is powered by sunlight. Capturing sunlight is the main agenda for survival in most organisms. This is done using the process of photosynthesis. Photosynthesis involves a complex machinery of photosystems and molecular antennas. This is where the bacteriordhodopsins come in in the archaebacteria with a simpler solution to capturing sunlight. When powered by sunlight, bacteriorhodopsin pumps protons across membranes making the cell extremely alkaline on the inside and when these protons flow back in via ATP synthase, ATP is produced powering the cell. Therefore, bacteriorhodopsin is one of the most important sources of energy to the cell.

Proteorhodopsin is again another light dependent proton pump. It has a high phylogenetic diversity in the environment reflecting functional diversity as well. Proteorhodopsin is the most important source resulting in prolonged starvation survival, multiplied growth and faster movement. It helps bacteria to produce energy without the use of organic carbon thus aiding survival under extreme conditions.

X-ray diffraction studies of the molecules aided in understanding and developing processes for bacteriorhodopsin and proteorhodopsin.

b. Proteorhodopsin family is a huge family of over 50 photoactive proteins found widespread in eukaryotes (protae), archae ans marine planktonic bacteria. It was first discovered in bacteria. The genes for these molecules have been identified in extreme environments as in the Red Sea, the North Sea, the Sargasso Sea, the Sea of Japan, and the Meditteranean. Bacteriorhodopsin is used by Archae and the most studied organism would be the halobacteria. They are found in extremely alkaline environment as in the Dead Sea, the Great Salt Lake and Lake Magadi. The fact that the genes for these proteins can be preserved under extreme environments under long spans of time proves its longevity and sustenance in existing and spreading.

3. The fuctional studies carried out on these genes prove that these genes are essential in providing an ecological advantage to the microbes that carry them. These proteins help in maintaining the alkaline environment inside the cell and across the membrane so that the pH inside the cell matches the outside environment aiding in survival. They also help in providing energy through methods that do not require organic carbon. This particularly aids in survival during starvation period and extreme conditions. The evidence for survival can be proved from the microbes that carry these proteins and thus can survive in extreme atmospheres as the Dead Sea, the Red Sea and so on wherein even the macroscopic aquatic organisms such as fish and plants have not evolved enough to survive.

Bacteriorhodopsin:

  

Proteorhodopsin: