PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of jbacterPermissionsJournals.ASM.orgJournalJB ArticleJournal InfoAuthorsReviewers
 
J Bacteriol. 1974 June; 118(3): 928–934.
PMCID: PMC246841

Proline Excretion and Indirect Suppression in Escherichia coli and Salmonella typhimurium

Abstract

The last step in proline biosynthesis in Escherichia coli K-12, Salmonella typhimurium LT7, and a number of other enterobacterial isolates is regulated so that no proline is excreted, even if excess Δ1-pyrroline-5-carboxylate, the immediate precursor of proline, is added to a culture. In proline auxotrophs blocked at an early step in proline biosynthesis (proA or proB), reversion to prototrophy is often due to a mutation in the arginine pathway which diverts N-acetyl glutamate γ-semialdehyde to proline synthesis, thus bypassing the proA or proB block. In such double mutants (proAB, argD), the last step in proline synthesis appears to be unregulated, since proline is excreted. Feedback inhibition and repression of the arginine pathway overcomes indirect suppression (restoring the Pro phenotype), but proline regulation is not restored; double mutants still excrete proline when fed Δ1-pyrroline-5-carboxylate exogeneously. A new class of proline analogue-resistant mutant, due to mutation at argD, is also described.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.1M), or click on a page image below to browse page by page.

Images in this article

Click on the image to see a larger version.

Articles from Journal of Bacteriology are provided here courtesy of American Society for Microbiology (ASM)