title: Zn²+-induced rearrangement of the disordered TPPP/p25 affects its microtubule assembly and GTPase activity.
abstract: Tubulin polymerization promoting protein/p25 (TPPP/p25) modulates the dynamics and stability of the microtubule system and plays crucial role in the myelination of oligodendrocytes. Here we showed by CD, fluorescence, and NMR spectroscopies that Zn(2+) is the first ligand that induces considerable rearrangement of the disordered TPPP/p25. Zinc finger motif (His(2)Cys(2)) (His(61)-Cys(83)) was identified within the flexible region of TPPP/p25 straddled by extended unstructured N- and C-terminal regions. The specific binding of the Zn(2+) to TPPP/p25 induced the formation of molten globule but not that of a well-defined tertiary structure. The Zn(2+)-induced partially folded structure accommodating the zinc binding motif is localized at the single Trp(76)-containing region as demonstrated by fluorescence resonance energy transfer and quenching experiments. We showed that the Zn(2+)-induced change in the TPPP/p25 structure modified its interaction with tubulin and GTP coupled with functional consequences: the TPPP/p25-promoted tubulin polymerization was increased while the TPPP/p25-catalyzed GTPase activity was decreased as detected by turbidimetry and by malachite green phosphate release/(31)P NMR assays, respectively. The finding that the Zn(2+) of the bivalent cations can uniquely influence physiological relavant interactions significantly contributes to our understanding of the role of Zn(2+)-related TPPP/p25 processes in the differentiation/myelination of oligodendrocytes possessing a high-affinity Zn(2+) uptake mechanism.
authors: Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, H-1113 Budapest, Hungary.
authors: Ágnes
authors: Á
authors: Zotter
authors: Judit
authors: J
authors: Oláh
authors: Emma
authors: E
authors: Hlavanda
authors: Andrea
authors: A
authors: Bodor
authors: András
authors: A
authors: Perczel
authors: Krisztián
authors: K
authors: Szigeti
authors: Judit
authors: J
authors: Fidy
authors: Judit
authors: J
authors: Ovádi
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D008870:Microtubules / Q000737:chemistry* / Q000201:enzymology / Q000473:pathology; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000502:physiology; D058105:Polymerization; D011485:Protein Binding; D015032:Zinc / Q000737:chemistry*
chemical_list: D008024:Ligands; D009419:Nerve Tissue Proteins; C118136:TPPP protein, human; D020558:GTP Phosphohydrolases; D015032:Zinc