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Novel methyl transfer during chemotaxis in Bacillus subtilis. Biochemistry 1989 Jun 27;28(13):5585-9

Date

06/27/1989

Pubmed ID

2505839

DOI

10.1021/bi00439a037

Scopus ID

2-s2.0-0024354885   23 Citations

Abstract

If Bacillus subtilis is incubated in radioactive methionine in the absence of protein synthesis, the methyl-accepting chemotaxis proteins (MCPs) become radioactively methylated. If the bacteria are further incubated in excess nonradioactive methionine ("cold-chased") and then given the attractant aspartate, the MCPs lose about half of their radioactivity due to turnover, in which lower specific activity methyl groups from S-adenosylmethionine (AdoMet) replace higher specific activity ones. Due to the cold-chase, the specific activity of the AdoMet pool is reduced at least 2-fold. If, later, the attractant is removed, higher specific activity methyl groups return to the MCPs. Thus, there must exist an unidentified methyl carrier that can "reversibly" receive methyl groups from the MCPs. In a similar experiment, labeled cells were transferred to a flow cell and exposed to addition and removal of attractant and of repellent. All four kinds of stimuli were found to cause methanol production. Bacteria with maximally labeled MCPs were exposed to many cycles of addition and removal of attractant; the maximum amount of radioactive methanol was evolved on the third, not the first, cycle. This result suggests that there is a precursor-product relationship between methyl groups on the MCPs and on the unidentified carrier, which might be the direct source of methanol. However, since no methanol was produced when a methyltransferase mutant, whose MCPs were unmethylated, was exposed to addition and removal of attractant or repellent, the methanol must ultimately derive from methylated MCPs.

Author List

Thoelke MS, Kirby JR, Ordal GW

Author

John Kirby PhD Chair, Center Associate Director, Professor in the Microbiology and Immunology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Bacillus subtilis
Bacterial Proteins
Chemotactic Factors
Chemotaxis
Kinetics
Membrane Proteins
Methanol
Methionine
Methyl-Accepting Chemotaxis Proteins
Methylation