Chitin synthase localization in the diatom Thalassiosira pseudonana

Chitin constitutes an abundant component in many biologically formed minerals (biominerals). While the role of chitin for the formation and properties of calcium-based biominerals has been extensively studied, little is known about its role in silica-based biominerals. Furthermore, there is hardly any information about the enzyme machinery for chitin biosynthesis in biomineral-forming organisms. Here we have identified a chitin synthase, chs7305, in the diatom Thalassiosira pseudonana. In stationary cells, chs7305 is located specifically in a ring pattern in the region of the silicified girdle bands. The expression pattern of the chs7305 gene and the co-localization of the encoded enzyme with chitin provides evidence for the importance of chitin synthesis for cell wall function under nutrient limited conditions. Chs7305 is the first chitin synthase that has been localized in a diatom.