Molecular cloning of, and phylogenetic analysis of, an actin in Naegleria fowleri.

We cloned and sequenced an intronless actin gene from the amoebo-flagellate Naegleria fowleri, LEE strain, an opportunistic pathogen of man. Codon usage and third-position-codon nucleotide frequency were significantly different from Acanthamoeba, another amoeba genus which also includes opportunistic pathogens of man. Between the two amoebae, actin peptide sequences were 92.8% similar, while nucleotide sequences were only 70% similar. A phylogenetic reconstruction of actin amino acid sequences, using a distance method, placed Naegleria in a cluster with Plasmodium and Entamoeba.