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Characterization of a novel kinase involved in biomineralization of diatom silica
Author(s) -
Sheppard Vonda Chantal,
Hipp Dustin,
Poulsen Nicole,
Kroger Nils
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.lb186
Subject(s) - biomineralization , kinase , microbiology and biotechnology , golgi apparatus , protein kinase domain , phosphorylation , diatom , biology , chemistry , biochemistry , endoplasmic reticulum , frustule , botany , gene , mutant , paleontology
Diatoms are unicellular, eukaryotic algae that produce cell walls made of intricately nanopatterned SiO 2 (silica). Formation of diatom silica involves highly phosphorylated proteins (silaffins and silacidins), analogous to other biomineralization systems (e.g., human bone and teeth), which also depend on diverse sets of phosphoproteins. The phosphate moieties on biomineralization proteins are essential for their mineral formation, yet the kinases catalyzing their attachment have not been identified in any organism. Such kinases are expected to reside within in the secretory pathway (endoplasmic reticulum, Golgi apparatus) through which the biomineralization proteins pass on their route to the biomineral forming compartment (extracellular space or specific intracellular vesicle). Here we present data on the characterization of a novel kinase, tpSTK1, which is strongly upregulated during silica formation in the diatom T. pseudonana . TpSTK1 is an abundant component of the ER lumen, and is capable of phosphorylating silaffins but not silacidins. Bioinformatic analysis identified tpSTK1 homologs in other diatom species, but only weak homology to kinases from other organisms, suggesting that tpSTK1 belongs to a novel family of kinases. TpSTK1 is the first molecularly characterized kinase that appears to catalyze phosphorylation of biomineral forming proteins in vivo.