Cell biology of anaerobic ammonium-oxidizing bacteria

Contains fulltext : 66946.pdf (publisher's version ) (Open Access)Anammox bacteria perform anaerobic ammonium oxidation to dinitrogen gas and belong to the phylum Planctomycetes. Whereas most Prokaryotes consist of one compartment, the cytoplasm bounded by the cytoplasmic membrane and cell wall, the species within this phylum are compartmentalized by intracellular membranes. In the anammox case, compartmentalization results in the cytoplasm being divided into three compartments surrounded by individual bilayer membranes. The anammox cell plan thus consists of (from out- to inside): the paryphoplasm, the riboplasm (containing the ribosomes and the nucleoid) and the anammoxosome. The innermost compartment, the anammoxosome, has been speculated to be the locus of anammox catabolism. This hypothesis is based upon the immunogold localization of one of the key enzymes of the anammox reaction, hydrazine/hydroxylamine oxidoreductase, to the anammoxosome. In the hypothesis, the anammoxosome membrane is energized by the translocation of protons from the riboplasm to the anammoxosome. This creates a proton motive force that could be used to drive ATP synthesis by anammoxosome membrane-bound ATPases. The research presented in this thesis uses a combination of genome analysis, molecular tools and transmission electron microscopy including electron tomography to investigate whether the anammoxosome is a true bacterial organelle: a separate compartment with a specific function inside the cell. The results obtained support both the hypothesis that the anammoxosome compartment is indeed the place where the anammox catabolism takes place and that there is no connection between the anammoxosome membrane and the intracytoplasmic membrane. This suggests that anammox bacteria have evolved a true bacterial organelle with a similar function as the eukaryotic mitochondrion: energy metabolism.RU Radboud Universiteit Nijmegen, 3 maart 2008Promotores : Jetten, M.S.M., Kuenen, J.G. Co-promotores : Strous, M., Geerts, W.199 p

Application, eco-physiology and biodiversity of anaerobic ammonium-oxidizing bacteria.

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Editorial: Planctomycetes-verrucomicrobia-chlamydiae bacterial superphylum: New model organisms for evolutionary cell biology

Contains fulltext : 176766.pdf (publisher's version ) (Open Access

Anammox-growth physiology, cell biology, and metabolism

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Cargo-loading of hybrid cowpea chlorotic mottle virus capsids via a co-expression approach

Capsids of the cowpea chlorotic mottle virus (CCMV) are great candidates for the development into in vivo catalytic or therapeutic nanocarriers. However, due to their limited intrinsic stability at physiological pH, thus far no methods exist for incorporating cargo into these nanoparticles in cellulo. Here, we employ a stabilized VW1-VW8 ELP-CCMV variant for the development of a co-expression-based cargo-loading approach. Co-expression of the non-functionalized VW1-VW8 ELP-CCMV coat protein with fusion proteins with enhanced green fluorescent protein (mEGFP) and pyrrolysine synthase D (PylD) in E. coli enabled the purification of cargo-loaded capsids from the bacteria directly either via affinity chromatography or PEG-precipitation and subsequent size exclusion chromatography. Microscopy results indicated that the co-expression does not harm the E. coli cells and that proper folding of the mEGFP domain is not hampered by the co-assembly. Our co-expression strategy is thus a suitable approach to produce cargo-loaded CCMV nanoparticles

Anammoxosomes of anaerobic ammonium-oxidizing planctomycetes

Contains fulltext : 36094.pdf (publisher's version ) (Closed access

Mimicking the oxygen minimum zones: Stimulating interaction of aerobic archaeal and anaerobic bacterial ammonia oxidizers in a laboratory‐scale model system

Contains fulltext : 103533.pdf (publisher's version ) (Open Access

Combined structural and chemical analysis of the anammoxosome: A membrane-bounded intracytoplasmic compartment in anammox bacteria

Contains fulltext : 35005.pdf (publisher's version ) (Closed access)Anammox bacteria have unique intracellular membranes that divide their cytoplasm into three separate compartments. The largest and innermost cytoplasmic compartment, the anammoxosome, is hypothesized to be the locus of all catabolic reactions in the anammox metabolism. Electron tomography showed that the anammoxosome and its membrane were highly folded. This finding was confirmed by a transmission electron microscopy study using different sample preparation methods. Further, in this study electron-dense particles were observed and electron tomography showed that they were confined to the anammoxosome compartment. Energy dispersive X-ray analysis revealed that these particles contained iron. The functional significance of a highly folded anammoxosome membrane and intracellular iron storage particles are discussed in relation to their possible function in energy generation