Files in this item
|(no description provided)|
|Title:||Chemotaxis Methyltransferase Ii From Bacillus Subtilis|
|Department / Program:||Biochemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Chemotaxis is the process by which motile cells sense and respond to their chemical environment. Following a period of time during which chemotactic bacteria respond to chemical stimulation, they revert to their pre-stimulus behavior, or adapt. Biochemically, adaptation is correlated with the methylation or demethylation of certain integral membrane proteins, the methyl-accepting chemotaxis proteins (MCPs). We have purified and characterized a chemotaxis methyltransferase (methyltransferase II) from Bacillus subtilis. By using a combination of DEAE Bio-Gel A chromatography, CM Bio-Gel A chromatography, ammonium sulfate fractionation, and S-adenosylhomocysteine affinity chromatography, a virtually homogeneous product was obtained.
The enzyme was shown to be a monomer with a native molecular weight of 30,000, a K(,m) for S-adenosylmethionine of 5 (mu)M, and a K(,i) for S-adenosylhomocysteine of 0.2 (mu)M. The MCP methylation reaction in vitro was activated by divalent cation and inhibited by NaCl or KCl. It had a pH optimum of 7 and a temperature optimum of 20-25(DEGREES)C. The linkage between the MCP and the transferred methyl group was preliminarily characterized as gammaglutamyl methyl ester.
Methyltransferase II appeared to have the ability to gain access to the intracellular space in permeabilization assays. It was also determined that a 68,000 molecular weight cytoplasmic protein (with two sub-units) could serve as a methyltransferase II substrate. The cytoplasmic protein was partially purified and characterized.
Finally, functional homology between Bacillus subtilis methyl-transferase II and Escherichia coli cheR protein was established.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
|Date Available in IDEALS:||2014-12-15|