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Expression of the gltP gene of Escherichia coli in a glutamate transport‐deficient mutant of Rhodobacter sphaeroides restores chemotaxis to glutamate
Author(s) -
Jacobs Mariken H.J.,
Heide Tiemen,
Tolner Berend,
Driessen Arnold J.M.,
Konings Wil N.
Publication year - 1995
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1995.mmi_18040641.x
Subject(s) - rhodobacter sphaeroides , biology , chemotaxis , biochemistry , mutant , glutamate receptor , permease , amino acid , glutamic acid , glutamine , escherichia coli , gene , receptor , photosynthesis
Rhodobacter sphaeroides is chemotactic to glutamate and most other amino acids. In Escherichia coli , chemotaxis involves a membrane‐bound sensor that either binds the amino acid directly or interacts with the binding protein loaded with the amino acid. In R. sphaeroides , chemotaxis is thought to require both the uptake and the metabolism of the amino acid. Glutamate is accumulated by the cells via a binding protein‐dependent system. To determine the role of the binding protein and transport in glutamate taxis, mutants were created by Tn 5 insertion mutagenesis and selected for growth in the presence of the toxic glutamine analogue γ‐glutamyl‐hydrazide. One of the mutants, R. sphaeroides MJ7, was defective in glutamate uptake but showed wild‐type levels of binding protein. The mutant showed no chemotactic response to glutamate. Both glutamate uptake and chemotaxis were recovered when the gltP gene, coding for the H + ‐linked glutamate carrier of E. coli , was expressed in R. sphaeroides MJ7. It is concluded that the chemotactic response to glutamate strictly requires uptake of glutamate, supporting the view that intracellular metabolism is needed for chemotaxis in R. sphaeroides .