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J Bacteriol. 1973 July; 115(1): 205-212
Copyright © 1973 American Society for Microbiology. All Rights Reserved.

A Bifunctional Enzyme in Pseudomonas aeruginosa: a New Pattern in the Organization of Enzymes Concerned with Phenylalanine and Tyrosine Biosynthesis

S. I. Ahmed1 and J. J. R. Campbell

a Department of Microbiology, The University of British Columbia, Vancouver 8, Canada

ABSTRACT

Two isozymes of chorismate mutase (CA mutase1 and CA mutase2) and two isozymes of prephenate dehydratase (PPA dehydratase1 and PPA dehydratase2) have been found in Pseudomonas aeruginosa. The activities CA mutase2-PPA dehydratase2 catalyzing phenylalanine biosynthesis have been purified almost 40-fold and were found to be associated as a bifunctional enzyme or an enzyme complex. The enzymes specific for tyrosine biosynthesis did not appear to manifest such physical association. Thus, the organization of enzymes concerned with phenylalanine and tyrosine biosynthesis in P. aeruginosa is unique and is unlike most other organisms. Single site mutants have been isolated which have lost both CA mutase2-PPA dehydratase2 activities resulting in a requirement for phenylalanine for growth. Single site revertants of these mutants regained both these activities simultaneously and were able to grow on minimal medium. A mutant, r6, was also isolated which had normal CA mutase2 but lacked PPA dehydratase2 activity.

FOOTNOTES

1 Present address: Department of Oceanography, University of Washington, Seattle, Wash. 98195.

J Bacteriol. 1973 July; 115(1): 205-212
Copyright © 1973 American Society for Microbiology. All Rights Reserved.





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