Article

Characterization of a 200-kDa diatom protein that is specifically associated with a silica-based substructure of the cell wall.

Lehrstuhl für Biochemie I, Universität Regensburg, Germany.
European Journal of Biochemistry (impact factor: 3.58). 12/1997; 250(1):99-105. pp.99-105
Source: PubMed

ABSTRACT The cell wall of a diatom is made up of a silica-based scaffold and organic macromolecules. Proteins located in the cell wall are believed to control morphogenesis of the species-specific silica structures of the scaffold. However, data that correlate distinct silica elements and specific proteins within the diatom cell wall have not been reported. Here, the cell wall protein HEP200 (200-kDa HF-extractable protein) from the diatom Cylinidrotheca fusiformis is identified and characterized. HEP200 is tightly associated with a substructure of the silica scaffold. It is a member of a new protein family, of which two more members are identified. Each member displays the same bipartite structure. The N-terminal part consists of a variable number of a repeated sequence motif (PSCD domain), whereas the C-terminal part is unique. Immunolocalization experiments revealed the arrangement of different proteins within the cell wall. Frustulins, a previously described group of glycoproteins, constitute the outer coat of the cell wall and exhibit a ubiquitous distribution. In contrast, HEP200 is specifically located at a subset of about six silica strips in intact cell walls, shielded by frustulins. This study therefore identifies a diatom cell wall protein (HEP200) that is associated with a distinct substructure of the silica scaffold.

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Keywords

200-kDa HF-extractable protein
 
bipartite structure
 
C-terminal part
 
cell wall protein HEP200
 
control morphogenesis
 
correlate distinct silica elements
 
diatom cell wall
 
diatom cell wall protein
 
diatom Cylinidrotheca fusiformis
 
Immunolocalization experiments
 
intact cell walls
 
member displays
 
N-terminal part
 
new protein family
 
organic macromolecules
 
PSCD domain
 
repeated sequence motif
 
silica-based scaffold
 
species-specific silica structures
 
variable number