Characterization of an endoplasmic reticulum-associated silaffin kinase from the diatom Thalassiosira pseudonana.
J Biol Chem
; 285(2): 1166-76, 2010 Jan 08.
Article
em En
| MEDLINE
| ID: mdl-19889629
ABSTRACT
The formation of SiO(2)-based cell walls by diatoms (a large group of unicellular microalgae) is a well established model system for the study of molecular mechanisms of biological mineral morphogenesis (biomineralization). Diatom biomineralization involves highly phosphorylated proteins (silaffins and silacidins), analogous to other biomineralization systems, which also depend on diverse sets of phosphoproteins (e.g. mammalian teeth and bone, mollusk shells, and sponge silica). The phosphate moieties on biomineralization proteins play an essential role in mineral formation, yet the kinases catalyzing the phosphorylation of these proteins have remained poorly characterized. Recent functional genomics studies on the diatom Thalassiosira pseudonana have revealed >100 proteins potentially involved in diatom silica formation. Here we have characterized the biochemical properties and biological function of one of these proteins, tpSTK1. Multiple tpSTK1-like proteins are encoded in diatom genomes, all of which exhibit low but significant sequence similarity to kinases from other organisms. We show that tpSTK1 has serine/threonine kinase activity capable of phosphorylating silaffins but not silacidins. Cell biological and biochemical analysis demonstrated that tpSTK1 is an abundant component of the lumen of the endoplasmic reticulum. The present study provides the first molecular structure of a kinase that appears to catalyze phosphorylation of biomineral forming proteins in vivo.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteínas Quinases
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Diatomáceas
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Dióxido de Silício
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Proteínas de Algas
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Retículo Endoplasmático
Tipo de estudo:
Risk_factors_studies
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Estados Unidos