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A C-terminal phosphatase module conserved in vertebrate CMP-sialic acid synthetases provides a tetramerization interface for the physiologically active enzyme.
Oschlies, Melanie; Dickmanns, Achim; Haselhorst, Thomas; Schaper, Wiebke; Stummeyer, Katharina; Tiralongo, Joe; Weinhold, Birgit; Gerardy-Schahn, Rita; von Itzstein, Mark; Ficner, Ralf; Münster-Kühnel, Anja-K.
Afiliação
  • Oschlies M; Institut für Zelluläre Chemie, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
J Mol Biol ; 393(1): 83-97, 2009 Oct 16.
Article em En | MEDLINE | ID: mdl-19666032
The biosynthesis of sialic acid-containing glycoconjugates is crucial for the development of vertebrate life. Cytidine monophosphate-sialic acid synthetase (CSS) catalyzes the metabolic activation of sialic acids. In vertebrates, the enzyme is chimeric, with the N-terminal domain harboring the synthetase activity. The function of the highly conserved C-terminal domain (CSS-CT) is unknown. To shed light on its biological function, we solved the X-ray structure of murine CSS-CT to 1.9 A resolution. CSS-CT is a stable shamrock-like tetramer that superimposes well with phosphatases of the haloacid dehalogenase superfamily. However, a region found exclusively in vertebrate CSS-CT appears to block the active-site entrance. Accordingly, no phosphatase activity was observed in vitro, which points toward a nonenzymatic function of CSS-CT. A computational three-dimensional model of full-length CSS, in combination with in vitro oligomerization studies, provides evidence that CSS-CT serves as a platform for the quaternary organization governing the kinetic properties of the physiologically active enzyme as demonstrated in kinetic studies.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: N-Acilneuraminato Citidililtransferase / Multimerização Proteica Limite: Animals Idioma: En Revista: J Mol Biol Ano de publicação: 2009 Tipo de documento: Article País de afiliação: Alemanha

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: N-Acilneuraminato Citidililtransferase / Multimerização Proteica Limite: Animals Idioma: En Revista: J Mol Biol Ano de publicação: 2009 Tipo de documento: Article País de afiliação: Alemanha