The HaloEd ProjectA web site dedicated to biotechnology education |
|
|
| UMBI | COMB | Teaching Kits | Outreach Activities | Graduate Education | |
|
|
Cellular Energetics Halobacteria can obtain energy using multiple pathways, using organic molecules in their environment aerobically or anaerobically, or phototrophically using the energy of light.
· Haloarchaea are generally amino acid utilizing facultative aerobes requiring a number of growth factors and slightly elevated temperatures (38-45oC) for optimal growth. · Many haloarchaea grow in the absence of oxygen via dissimilatory nitrate reduction and denitrification, fermentation of different sugars, breakdown of arginine and use of light energy, mediated by retinal pigments. · Haloarchaea have purple membrane, which are specialized regions of the cell membrane, which contain a two-dimensional crystalline lattice of bacteriorhodopsin. Bacteriorhodopsin contains a protein moiety, bacterio-opsin and a covalently-bound chromophore, retinal, and acts as a light-driven transmembrane protein pump (see Figure). The membrane potential generated can be used to drive ATP synthesis and support some phototrophic growth. · Retinal is produced by oxidative cleavage of b-carotene (requiring molecular oxygen). · Halorhodopsin is an inwardly-directed light-driven chloride pump and may contribute to phototrophic growth.
Since the genome of Halobacterium sp. NRC-1 has been sequenced, we are able to determine a lot of the metabolic pathways, including those for cellular energetics (see diagram below).
|
|
|
Copyright © 2003-2006 UMBI/COMB, |
|
