A biochemical mechanism for bacterial chemotaxis

George W. Ordaq, Russell B. Fields

Research output: Contribution to journalArticlepeer-review


Peritrichous bacteria alternately swim and tumble (thrash about with little forward progress). By selective modulation of tumbling frequency, these bacteria carry out chemotaxis, which is migration to higher concentrations of attractant or lower concentrations of repellent. A model for chemotaxis is presented in which tumbling frequency is regulated by concentration of Ca2+ ion at the switch that controls tumbling and swimming. Attractants cause decreased levels of free cytoplasmic Ca2+ ion due to binding of Ca2+ ion by specific proteins. This Ca2+ ion is released when these proteins become methylated. An alternative model. involving a cytoplasmic metabolite "compound X", is discussed.

Original languageEnglish (US)
Pages (from-to)491-500
Number of pages10
JournalJournal of Theoretical Biology
Issue number4
StatePublished - Oct 21 1977

ASJC Scopus subject areas

  • Statistics and Probability
  • Modeling and Simulation
  • General Biochemistry, Genetics and Molecular Biology
  • General Immunology and Microbiology
  • General Agricultural and Biological Sciences
  • Applied Mathematics


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