Letter | Published:

Methionine Biosynthesis and Utilization in Pseudomonas tabaci and Ps. angulata

Naturevolume 180pages12821283 (1957) | Download Citation



Pseudomonas tabaci, the wildfire bacterium of tobacco, produces an exotoxin, detectable by a bacteria-free, chlorotic halo surrounding the necrotic focus of infection in the leaf at the site of inoculation ; Ps. angulata, the causative agent of angular leaf spot of tobacco, does not produce the chlorotic halo. These species are indistinguishable when Ps. tabaci is attenuated and no longer produces the exotoxin1. Since the exotoxin behaves as a methionine anti-metabolite for the host cells2, the effect of a second methionine antimetabolite, methionine sulphoximine, on toxigenic strains of Ps. tabaci was determined. Furthermore, eighteen independently isolated, methionine-requiring mutants of this species were tested to establish the site of the block in the biosynthetic pathway for this amino-acid.

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  1. 1

    Braun, A. C., Phytopath., 27, 283 (1937).

  2. 2

    Braun, A. C., Phytopath., 45, 659 (1955).

  3. 3

    Vogel, H. J., and Bonner, D. M., J. Biol. Chem., 218, 97 (1956).

  4. 4

    Garber, E. D., Shaeffer, Susan G., and Goldman, M., J. Gen. Microbiol., 14, 261 (1956).

  5. 5

    Sager, R., Genetics, 40, 476 (1955).

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  1. Department of Botany, University of Chicago, Chicago, 37, Illinois

    • E. D. GARBER


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