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A Cell Cycle-Regulated Adenine Dna Methyltransferase From Caulobacter Crescentus Processively Methylates Gantc Sites On Hemimethylated Dna, Craig Stephens, Anthony J. Berdis, Irene Lee, James K. Coward, Rachel Wright, Lucy Shapiro, Stephen J. Benkovic
A Cell Cycle-Regulated Adenine Dna Methyltransferase From Caulobacter Crescentus Processively Methylates Gantc Sites On Hemimethylated Dna, Craig Stephens, Anthony J. Berdis, Irene Lee, James K. Coward, Rachel Wright, Lucy Shapiro, Stephen J. Benkovic
Biology
The kinetic properties of an adenine DNA methyltransferase involved in cell cycle regulation of Caulobacter crescentus have been elucidated by using defined unmethylated or hemimethylated DNA (DNAHM) substrates. Catalytic efficiency is significantly enhanced with a DNAHM substrate. Biphasic kinetic behavior during methyl incorporation is observed when unmethylated or DNAHM substrates are used, indicating that a step after chemistry limits enzyme turnover and is most likely the release of enzyme from methylated DNA product. The enzyme is thermally inactivated at 30 degrees C within 20 min; this process is substantially decreased in the presence of saturating concentrations of DNAHM, suggesting that …
Identification Of The Flii And Flij Components Of The Caulobacter Flagellar Type Iii Protein Secretion System, Craig Stephens, Chris Mohr, Charles Boyd, Janine Maddock, James Gober, Lucy Shapiro
Identification Of The Flii And Flij Components Of The Caulobacter Flagellar Type Iii Protein Secretion System, Craig Stephens, Chris Mohr, Charles Boyd, Janine Maddock, James Gober, Lucy Shapiro
Biology
Caulobacter crescentus is motile by virtue of a polar flagellum assembled during the predivisional stage of the cell cycle. Three mutant strains in which flagellar assembly was blocked at an early stage were isolated. The mutations in these strains mapped to an operon of two genes, fliI and fliJ, both of which are necessary for motility. fliI encodes a 50-kDa polypeptide whose sequence is closely related to that of the Salmonella typhimurium FliI protein, an ATPase thought to energize the export of flagellar subunits across the cytoplasmic membrane through a type III protein secretion system. fliJ encodes a 16-kDa hydrophilic …