Simultaneous presence of fhs and purT genes is disadvantageous for the fitness of Escherichia coli growth

Srinivas Aluri, Kervin Rex, Umesh Varshney

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


In bacteria, alternate mechanisms are known to synthesize N10-formyltetrahydrofolate (N10-formyl-THF) and formyl glycinamide ribotide (fGAR), which are important in purine biosynthesis. In one of the mechanisms, a direct transfer of one carbon unit from formate allows Fhs to convert tetrahydrofolate to N10-formyl-THF, and PurT to convert glycinamide ribotide (GAR) to fGAR. Our bioinformatics analysis of fhs and purT genes (encoding Fhs and PurT) showed that in a majority of bacteria (~94%), their presence was mutually exclusive. A large number of organisms possessing fhs lacked purT and vice versa. The phenomenon is so penetrating that even within a genus (Bacillus) if a species possessed fhs it lacked purT and vice versa. To investigate physiological importance of this phenomenon, we used Escherichia coli, which naturally lacks fhs (and possesses purT) as model. We generated strains, which possessed fhs and purT genes in singles or together. Deletion of purT from E. coli in the presence or absence of fhs did not confer a detectable growth disadvantage in pure cultures. However, growth competition assays revealed that the strains possessing either of the single genes outcompeted those possessing both the genes suggesting that mutual exclusion of purT and fhs in organisms confers fitness advantage in mixed cultures.

Original languageEnglish (US)
Article numberfnv101
JournalFEMS Microbiology Letters
Issue number14
StatePublished - Jul 2015
Externally publishedYes


  • Anti-correlative presence of genes
  • Growth competitions
  • Growth fitness advantage

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology
  • Genetics


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