The N-terminal domain of the myelin enzyme 2′,3′-cyclic nucleotide 3′-phosphodiesterase: direct molecular interaction with the calcium sensor calmodulin

• Published in: Journal of neurochemistry 2012-11, Vol.123 (4), p.515-524
• Main Authors: Myllykoski, Matti, Itoh, Kouichi, Kangas, Salla M., Heape, Anthony M., Kang, Sung-Ung, Lubec, Gert, Kursula, Inari, Kursula, Petri
• Format: Article
• Language: English
• Subjects: 2',3'-Cyclic Nucleotide 3'-Phosphodiesterase - chemistry; 2',3'-Cyclic Nucleotide 3'-Phosphodiesterase - genetics; 2',3'-Cyclic Nucleotide 3'-Phosphodiesterase - metabolism; 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase; 3′-cyclic nucleotide 3′-phosphodiesterase; Animals; Antagonists; Biochemistry. Physiology. Immunology; Biological and medical sciences; Brain - cytology; Brain - metabolism; Brain research; calmodulin; Calmodulin - genetics; Calmodulin - metabolism; Chromatography, Affinity; Chromatography, Gel - methods; Crustacea; Embryo, Mammalian; Enzyme Inhibitors - pharmacology; Fundamental and applied biological sciences. Psychology; Ganglia, Spinal - drug effects; Ganglia, Spinal - metabolism; Humans; interaction; Invertebrates; Isolated neuron and nerve. Neuroglia; Mice; Mice, Inbred C57BL; Models, Molecular; Molecular Sequence Data; myelin; Nerve Fibers, Myelinated - metabolism; Neurochemistry; Oligodendroglia; Organ Culture Techniques; Phosphorylation - genetics; Physiology. Development; protein; Protein Binding - drug effects; Protein Binding - genetics; Protein Processing, Post-Translational - drug effects; Protein Processing, Post-Translational - physiology; Protein Structure, Tertiary - genetics; Protein Structure, Tertiary - physiology; Proteomics; Rats; Schwann Cells - enzymology; Surface Plasmon Resonance; Vertebrates: nervous system and sense organs
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/jnc.12000

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. The N‐terminal domain of the myelin enzyme CNPase binds calmodulin The membrane‐associated enzyme 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase (CNPase) is one of the most abundant proteins in the myelin sheath. In this study, we show that the CNPase N‐terminal domain interacts directly with the ubiquitous calcium sensor protein calmodulin. Our finding implies that the function of CNPase, which is currently poorly understood, could be regulated by cellular calcium levels.