title: The N-terminal domain of the myelin enzyme 2',3'-cyclic nucleotide 3'-phosphodiesterase: direct molecular interaction with the calcium sensor calmodulin.
abstract: 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) is a quantitatively major enzyme in myelin, where it localizes to the non-compact regions and is bound to the membrane surface. Although its catalytic activity in vitro has been characterized, the physiological function and in vivo substrate of CNPase remain unknown. Especially the N-terminal domain has been poorly characterized; previously, we have shown it is involved in CNPase dimerization and RNA binding. Here, we show that purified CNPase binds to the calcium sensor protein calmodulin (CaM) in a calcium-dependent manner; the binding site is in the N-terminal domain of CNPase. CaM does not affect the phosphodiesterase activity of CNPase in vitro, nor does it influence polyadenylic acid binding. The colocalization of CNPase and CaM during Schwann cell myelination in culture was observed, and CaM antagonists induced the colocalization of CNPase with microtubules in differentiated CG-4 oligodendrocytes. An analysis of post-translational modifications of CNPase from rat brain revealed the presence of two novel phosphorylation sites on Tyr110 and Ser169 within the N-terminal domain. The results indicate a role for the N-terminal domain of CNPase in mediating multiple molecular interactions and provide a starting point for detailed structure-function studies on CNPase and its N-terminal domain.
authors.affiliation: Department of Biochemistry, University of Oulu, Oulu, Finland.
authors.forename: Matti
authors.initials: M
authors.lastname: Myllykoski
authors.forename: Kouichi
authors.initials: K
authors.lastname: Itoh
authors.forename: Salla M
authors.initials: SM
authors.lastname: Kangas
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Heape
authors.forename: Sung-Ung
authors.initials: SU
authors.lastname: Kang
authors.forename: Gert
authors.initials: G
authors.lastname: Lubec
authors.forename: Inari
authors.initials: I
authors.lastname: Kursula
authors.forename: Petri
authors.initials: P
authors.lastname: Kursula
mesh_terms: D063309:2',3'-Cyclic Nucleotide 3'-Phosphodiesterase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism*; D002846:Chromatography, Affinity; D002850:Chromatography, Gel / Q000379:methods; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009413:Nerve Fibers, Myelinated / Q000378:metabolism; D009836:Oligodendroglia; D009924:Organ Culture Techniques; D010766:Phosphorylation / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology*; D040901:Proteomics; D051381:Rats; D012583:Schwann Cells / Q000201:enzymology; D020349:Surface Plasmon Resonance
chemical_list: D002147:Calmodulin; D004791:Enzyme Inhibitors; D063309:2',3'-Cyclic Nucleotide 3'-Phosphodiesterase