Ta0583, an archaeal actin homolog
Thermoplasma acidophilum (archaea,thermophile)
The shape of cells is very important to maintain their function. For example, endothelial cells are rather rigid in order to keep the shape of the tissue, while blood cells are flexible in the blood or lymph vessel. The shape of cells is regulated by the cytoskeletons that are composed of filamentous proteins dispersed over the intracellular space. One of the most important cytoskeletons for the maintenance of the cell shape is actin filament. Actin filament consists of a large number of actin proteins. Actin has endogenous ATPase activity that regulates the formation of the filament; ATP binding to actin accelerates the polymerization of actin, whereas ATP hydrolysis to ADP destabilizes the filament and shortens the length of the filament.
The protein described here is a homolog of actin, Ta0583, in an archaeon, T. acidophilum. Of course, cytoskelton is very important in archaea, but little is known about the counterparts of archaea. The group of Bracher repoted that Ta0583 has ATPase activity and the structure is very similar to the prokaryotic or eukaryotic actin. This result indicated that Ta0583 is an actin homolog in archaea. Since the abundance of Ta0583 in T. acidophilum cell is relatively low, they also suggested that Ta0583 might play a role in partitioning cell components during cell fission or maintenance of cell organization rather than in the shaping of the cell.
Protein Data Bank (PDB)
author: Daisuke Ino