The Acanthamoeba Shikimate Pathway Has a Unique Molecular Arrangement and Is Essential for Aromatic Amino Acid Biosynthesis

Protist. 2015 Feb;166(1):93-105. doi: 10.1016/j.protis.2014.12.001. Epub 2014 Dec 11.


The shikimate pathway is the only known biosynthetic route for de novo synthesis of aromatic compounds. It is described as an ancient eukaryotic innovation that has been retained in a subset of eukaryotes, replaced in plants through the acquisition of the chloroplast, but lost in many including humans. Herein, we demonstrate that Acanthamoeba castellanii possesses the shikimate pathway by biochemical and a combination of bioinformatics and molecular biological methods. The growth of A. castellanii (Neff strain and a recently isolated clinical specimen, both T4 genotypes) is inhibited by glyphosate [N-(phosphonomethyl) glycine], an inhibitor of EPSP synthase and the addition of phenylalanine and tryptophan, which are dependent on the shikimate pathway, rescued A. castellanii from glyphosate indicating that glyphosate was specific in action. A. castellanii has a novel complement of shikimate pathway enzymes including unique gene fusions, two Type I and one Type II DAHP synthases (for which their likely sensitivities to feedback inhibition by phenylalanine, tyrosine and tryptophan has been modelled) and a canonical chorismate synthase. The shikimate pathway in A. castellanii therefore has a novel molecular arrangement, is required for amino acid biosynthesis and represents an attractive target for antimicrobials.

Keywords: Acanthamoeba castellanii; glyphosate inihibition; novel molecular arrangement.; shikimate pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acanthamoeba castellanii / genetics*
  • Acanthamoeba castellanii / metabolism*
  • Amino Acids, Aromatic / biosynthesis*
  • DNA, Protozoan / chemistry
  • DNA, Protozoan / genetics
  • Metabolic Networks and Pathways / genetics*
  • Molecular Sequence Data
  • Sequence Analysis, DNA
  • Shikimic Acid / metabolism*


  • Amino Acids, Aromatic
  • DNA, Protozoan
  • Shikimic Acid

Associated data

  • GENBANK/KC471623
  • GENBANK/KC471624
  • GENBANK/KC471625
  • GENBANK/KC471626
  • GENBANK/KC471627
  • GENBANK/KC471628
  • GENBANK/KC479580
  • GENBANK/KC479581