CORET-CARUT

Last week, my Biochemistry lecturer gave me an assignment to be presented this Tuesday in front of the class. I volunteered myself to be the 5 first presenter not because I'm good or thought that I'm good. Actually it is just for fun. Hehe.. Do you think it's freak? Maybe.. Haha.. I choose "current issues on microbial usage in green energy" as the topic of my presentation. I decided to put up on my blog the summarize done from my readings just to share the knowledge. Be happy to read through.. (^_^)v

PROTEORHODOPSIN

What is Proteorhodopsin?

Proteorhodopsin is a photoactive retinylidene protein in marine bacterioplanktons. It is a light-absorbing pigment in oceanic bacteria in simple words. Just like the homologous pigment bacteriorhodopsin found in some Achaea, it consists of a transmembrane protein bound to a retinal molecule and functions as a light-driven proton pump.

When did it been discovered?

Proteorhodopsin was first discovered in 2000. It was found in the genomes of several species of uncultivated marine γ-proteobacteria present in the Eastern Pacific Ocean, Central North Pacific Ocean and Southern Ocean, Antarctica. Subsequently, genes of proteorhodopsin variants have been identified in samples from the Mediterranean and Red Seas and the Sargasso Sea and the Sea of Japan. These variants are not spread randomly, but have different distributions of absorption maxima along depth gradients and across locations.

How does it works?

When exposed to light, the photopigment moved ions across the bacteria’s cell membrane, showing that it could generate energy by absorbing light. This process is much simpler than the process of photosynthesis used by plants and algae.

The mechanism:

Model of the energy generating mechanism in marine bacteria. When sunlight strikes a rhodopsin molecule (1), it changes its configuration such that a proton is expelled from the cell (2). The chemical potential causes the proton to flow back into the cell (3), thus generating energy (4) in the form of adenosine triphosphate (5).

Who did the research?

This discovery was made by researchers at University of Kalmar in Sweden, led by Jarone Pinhassi in collaboration with researchers in Gothenburg, Sweden, and Spain. Further studies also have been made by researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley, scientists funded by the National Science Foundation (NSF) and affiliated with the Monterey Bay Aquarium Research Institute (MBARI).

MBARI contributors to proteorhodopsin project:

Oded Béjà, Lynne Christianson, Ed DeLong, Chris Preston, Marcelino Suzuki, Jose de la Torre

Berkeley researchers:

Derek Greenfield (left), Jessica Walter, Jan Liphardt and Carlos Bustamante used genetic engineering techniques to determine the function in bacteria of the light-sensitive protein proteorhodopsin.