Identification and Localization of Cyanophycin in Bacteria Cells via Imaging of the Nitrogen Distribution Using Energy-Filtering Transmission Electron Microscopy

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• 作者：Anne Koop ; Ingo Voss ; Andreas Thesing ; Helmut Kohl ; Rudolf Reichelt ; Alexander Steinbü ; chel
• 刊名：Biomacromolecules
• 出版年：2007
• 出版时间：September 2007
• 年：2007
• 卷：8
• 期：9
• 页码：2675 - 2683
• 全文大小：641K
• 年卷期：v.8,no.9(September 2007)
• ISSN：1526-4602

文摘

In this study the technique of energy-filtering transmission electron microscopy was applied to localize cyanophycin(CGP) in recombinant strains of Ralstonia eutropha. Since CGP is a polymer consisting of the amino acids aspartateand arginine, which functions as a temporary nitrogen reserve that is deposited as insoluble inclusions in thecytoplasm of the cell, its nitrogen content is significantly higher than that of the other cell matter. In this study,we recorded nitrogen distribution maps, which represent the location of CGP in ultrathin sections of resin-embeddedcells of recombinant strains of R. eutropha expressing the cyanophycin synthetase of Anabaena sp. strain PCC7120. Furthermore, the existence of nitrogen in CGP granules was additionally proven by recording electronenergy-loss spectra. The samples of R. eutropha H16 (pBBR1MCS-2::cphA1₇₁₂₀) revealed a second type of granule,which does not show nitrogen in the corresponding maps and which can be identified as an inclusion containingpoly(3-hydroxybutyric acid). The methods applied in this study are suitable to identify storage compounds withelevated nitrogen contents and to reveal their location in the bacterial cell. The methods are also very helpful todistinguish between inclusions of different chemical compositions that occur both at the same time in the cellsbut cannot or only hardly be distinguished by other methods.