Planarian peptidylglycine-hydroxylating monooxygenase, a neuropeptide processing enzyme, colocalizes with cytochrome b561 along the central nervous system.
Planarians are one of the simplest animal groups with a central nervous system. Their primitive central nervous system produces large quantities of a variety of neuropeptides, of which many are amidated at their C terminus. In vertebrates, peptide amidation is catalyzed by two enzymes [peptidylglycine alpha-hydroxylating monooxygenase (PHM) and peptidyl-alpha-hydroxylglycine alpha-amidating lyase] acting sequentially. In mammals, both enzymatic activities are contained within a single protein that is encoded by a single gene. By utilizing PCR with degenerate oligonucleotides derived from conserved regions of PHM, we succeeded in cloning a full-length cDNA encoding planarian PHM. The deduced amino acid sequence showed full conservation of five His residues and one Met residue, which bind two Cu atoms that are essential for the activity of PHM. Northern blot analysis confirmed the expression of a PHM mRNA of the expected size. Distribution of the mRNA was analyzed by in situ hybridization, showing specific expression in neurons with two morphologically distinct structures, a pair of the ventral nerve cords and the brain. The distribution of PHM was very similar to that of cytochrome b561. This indicates that the ascorbate-related electron transfer system operates in the planarian central nervous system to support the PHM activity and that it predates the emergence of Plathelminthes in the evolutionary history.
Asada
Akikazu
A
Department of Life Science, Graduate School of Life Science, University of Hyogo (formerly Himeji Institute of Technology), Hyogo, Japan.
Orii
Hidefumi
H
Watanabe
Kenji
K
Tsubaki
Motonari
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D001921:Brain / Q000378:metabolism*; D003001:Cloning, Molecular; D003573:Cytochrome b Group / Q000378:metabolism*; D005123:Eye / Q000378:metabolism; D017403:In Situ Hybridization; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism*; D010802:Phylogeny; D010932:Planarians / Q000201:enzymology*; D016415:Sequence Alignment
D003573:Cytochrome b Group; D009097:Multienzyme Complexes; C023646:cytochrome b561; D006899:Mixed Function Oxygenases; C035189:peptidylglycine monooxygenase