title: Primary structure and evolution of the ATP-binding domains of the P-type ATPases in Tetrahymena thermophila.
abstract: The P-type ATPases (e.g., Na+-K+-ATPase and Ca2+-ATPase) occur widely in living cells of fungi, Protozoa, plants, and animals. These ion pumps show a high degree of divergence in their primary structures but share a limited number of common amino acid residues for their ATP-catalytic function. Particularly, the amino acid sequences for the phosphorylation site (DKTGTLT) and the binding site for ATP (and its analogs; GDGVND) are conserved throughout evolution. Using two degenerate oligonucleotides corresponding to these regions, we applied a polymerase chain reaction (PCR) technique to the search for P-type ATPase isoforms, which will provide a clue to the evolutionary mechanisms of ion pumps in Tetrahymena thermophila. A total of 12 distinct P-type ATPase genes were identified. Sequence comparisons revealed that seven of them can be compiled into a multigene family, which is similar to animal Na+-K+- and H+-K+-ATPase genes. One of them is close to the sarco(endo)plasmic reticulum Ca2+-ATPase gene, and the other four share a significant homology with the gene encoding Plasmodium ATPase-1 whose function is unknown. A Northern blot analysis and reverse transcriptase-PCR demonstrated that all identified genes are expressed, but the expression levels vary widely under different culture conditions. A Southern blot analysis after pulse-field gel electrophoresis showed that all of these genes exist in T. thermophila macronuclei. The Na+-K+- and H+-K+-ATPase gene family has a high multiplicity (at least 10 different genes detected on genomic Southern blot analysis) and is distributed on four different macronuclear chromosomes. On the basis of a calculation with the amino acid sequences of the cloned cytoplasmic loop region (between the phosphorylation and the gamma-[4-(N-2-chloroethyl-N-methylamino)]-benzylamido ATP sites), the genes with >80% identity form a cognate linkage group within the same macronuclei chromosome, whereas the genes with <70% identity are separated in different chromosomes. The phylogenetic analysis showed that this multigene family is the result of a series of gene duplications.
authors.affiliation: Department of Medical Biochemistry, Ohio State University, Columbus 43210, USA.
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Takeyasu
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002875:Chromosomes; D019143:Evolution, Molecular; D018628:Gene Dosage; D005796:Genes; D008040:Genetic Linkage; D007527:Isoenzymes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016808:Tetrahymena thermophila / Q000201:enzymology*
chemical_list: D007527:Isoenzymes; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases