myxococcus xanthus essays

myxococcus xanthus essays The bacteria Myxococcus Xanthus is a decomposer that moves and forms fruiting bodies to reproduce. These fruiting bodies are mounds that grow into mushroom cloud like bodies, where cells differentiate on the inside to form small spores that are heat and desiccation resistant. In her discussion of Myxococcus Xanthus, Dr. Hartzell addresses various complexes that make flagella-less movement possible for the bacteria. The researchers traced cell movements and found that Myxococcus Xanthus moves at a rate of 2.5 micrometers per minute. A rate that is slower than continental drift (3 micrometers per minute). Cell movements occur in two different forms: social (moving in groups of cells) and adventurous (individuals moving). Movement is found to be gene determined. Two genes were found to be required for any movement: mgl A and mgl B. Furthermore, there are specific genes required for social movement and specific genes required for adventurous movement. Mgl A, a magnesium dependant, is a GTP-ase (a protein that binds and cleaves GTP to GDP) like Ras. It was found that mgl A was necessary for development of the fruiting body and for movement, but not for growth of the cell. When mgl A binds to GDP, it is inactive. However, when it binds GTP, it is active. Then mgl A was sequenced and found to have one of the Aspartine amino acids exchanged for a Threonine. If mgl A was mutated to replace Threonine with Asoartine (the way it is in most Ras proteins), no movement or formation of the fruiting body occurred. Also, induced activation of this protein (forcing GTP to bind to it) causes movement, but not development of the fruiting body. The calcium dependent mgl B protein is also required for movement. Found right next to mgl A and transcribed at the same time, mgl B is believed to be a guanyl nucleotide release factor (REM for short). REMs facilitate the release of GDP from Ras type proteins (mgl A) so that it can bind more G...