MOLECULAR-CLONING OF, AND PHYLOGENETIC ANALYSIS OF, AN ACTIN IN NAEGLERIA-FOWLERI

We cloned and sequenced an intronless actin gene from the amoebo-flage llate Naegleria fowleri, LEE strain, an opportunistic pathogen of man. Codon usage and third-position-codon nucleotide frequency were signif icantly different from Acanthamoeba, another amoeba genus which also i ncludes 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 s equences, using a distance method, placed Naegleria in a cluster with Plasmodium and Entamoeba.