title: Structure, expression and phylogenetic analysis of the gene encoding actin I in Pneumocystis carinii.
abstract: Actin is a major component of the cytoskeleton and one of the most abundant proteins found in eukaryotic cells. Comparative sequence analysis shows that this essential gene has been highly conserved throughout eukaryotic evolution making it useful for phylogenetic analysis. Complete cDNA clones for the actin-encoding gene were isolated and characterized from Pneumocystis carinii purified from immunosuppressed rat lungs. The nucleotide sequence encodes a protein of 376 amino acids. The predicted actin protein of P. carinii shares a high degree of conservation to other known actins. Only one major actin gene was found in P. carinii. The P. carinii actin sequence was compared with 30 other actin sequences. Gene phylogenies constructed using both neighbor-joining and protein parsimony methods places the P. carinii actin sequence closest to the majority of the fungi. Since the phylogenetic relationship of P. carinii to fungi and protists has been questioned, these data on the actin gene phylogeny support the grouping of P. carinii with the fungi.
authors.affiliation: Department of Pathology, School of Medicine, University of North Carolina, Chapel Hill 27599.
authors.forename: L D
authors.initials: LD
authors.lastname: Fletcher
authors.forename: J M
authors.initials: JM
authors.lastname: McDowell
authors.forename: R R
authors.initials: RR
authors.lastname: Tidwell
authors.forename: R B
authors.initials: RB
authors.lastname: Meagher
authors.forename: C C
authors.initials: CC
authors.lastname: Dykstra
mesh_terms: D000199:Actins / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D017931:DNA Primers; D004271:DNA, Fungal / Q000235:genetics; D056890:Eukaryota / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D011010:Pneumocystis / Q000145:classification* / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000199:Actins; D017931:DNA Primers; D004271:DNA, Fungal; D005656:Fungal Proteins