Hazelaar Sandra, van der Strate Han J, Gieskes Winfried W C, Vrieling Engel G
Department of Marine Biology, Center for Ecological and Evolutionary Studies, University of Groningen, P.O. Box 14, 9750 AA Haren, The Netherlands.
Biomol Eng. 2003 Jul;20(4-6):163-9. doi: 10.1016/s1389-0344(03)00044-3.
In diatom silicon biomineralization peptides are believed to play a role in silica precipitation and the consequent structure direction of the cell wall. Characterization of such peptides should reveal the nature of this organic-inorganic interaction, knowledge that may eventually well be used to expand the existing range of artificial silicas ("biomimicking"). Biochemical studies on Navicula pelliculosa revealed a set of proteins, which have a high affinity for a solid silica matrix; some were only eluted from the matrix when SDS-denaturation was applied. One of the proteins with an affinity for silica, about 8.5 kDa, is shown to be a homologue of ubiquitin on the basis of its N-terminal amino acid sequence; ubiquitin itself is a highly conserved 8.6 kDa protein that is involved in protein degradation. This finding is in line with a model of silica biomineralization in diatoms that implies the removal of templating polypeptides when pores in the growing cell wall develop. Western blotting with specific anti-ubiquitin antibodies confirmed cross-reactivity. Immunocytochemical localization of ubiquitin indicates that it is present along the diatom cell wall and inside pores during different stages of valve formation.
在硅藻的硅生物矿化过程中，肽类被认为在二氧化硅沉淀以及随之而来的细胞壁结构定向中发挥作用。对这类肽的表征应能揭示这种有机-无机相互作用的本质，这一知识最终可能会被用于扩展现有的人工二氧化硅范围（“生物模拟”）。对舟形藻的生化研究揭示了一组对固体二氧化硅基质具有高亲和力的蛋白质；有些蛋白质只有在应用SDS变性时才从基质上洗脱下来。其中一种对二氧化硅有亲和力的蛋白质，约8.5 kDa，根据其N端氨基酸序列显示为泛素的同源物；泛素本身是一种高度保守的8.6 kDa蛋白质，参与蛋白质降解。这一发现与硅藻中硅生物矿化的模型一致，该模型表明当生长中的细胞壁上的孔隙形成时，模板多肽会被去除。用特异性抗泛素抗体进行的蛋白质印迹证实了交叉反应性。泛素的免疫细胞化学定位表明，在瓣膜形成的不同阶段，它存在于硅藻细胞壁周围和孔隙内部。
