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FRIBIO2-FRIPRO forskerprosjekt, biologi

Nanowire-mediated iron acquisition in bacteria

Alternative title: Nanowire-drevet jernopptak hos bakterier

Awarded: NOK 7.9 mill.

Iron and manganese are essential nutrients for bacteria. However, in our oxygen-containing atmosphere, these elements are inaccessible for bacteria in many natural environments, as it is complexed with oxygen. Electron donation to these oxides can convert the iron into a form that can be utilized by bacteria. In this project, we have already demonstrated that bacterial pili play an important in accessing iron and manganese oxides. We are in in the process of identifying the molecular components that mediate electron donation to extra cellular electron acceptors and characterize electron donation characteristics. For this we have evaluated deletion mutants and constructed a mutation library that we screen for phenotypes in iron and manganese utilization. Furthermore, we perform characterize the electron donation characteristics of different mutants using electrode systems. We are also investigating and quantifying what sources of iron can be used by marine cyanobacteria. For this we have implemented a defined iron medium for growing cyanobacteria.

The project "Nanowire-mediated iron acquisition in bacteria" established a link between the ability of cyanobacteria to access iron that is contained in oxidized iron minerals. This link has been established through data obtained from physiological, electron microscopy, and gene expression data that uses wild-type and pilin deletion mutants. Genetic deletion of pili results in changes in the photosynthetic electron transport chain, as well as reductive nitrogen metabolism and extracellular carbohydrates.Furthermore, the main pilin in the model cyanobacterium Synechococcus sp. PCC 7002 has been identified as well as the operon for siderophore biosynthesis.

This project addresses the utilisation of a resource that is fundamental to life: Iron There is strong evidence that bacterial pili have a function in donating electrons to iron oxides. However, this electron disposal has so far only been interpreted as to enable respiration of soil bacteria in anaerobic conditions. In contrast, we have collected data that indicates that pili and a cytochrome are crucial for iron acquisition in the cyanobacterium Synechocystis sp. PCC 6803. We hypothesise that pili are meditating electron donation to iron oxides, thereby converting insoluble ferric iron (Fe3+) into soluble ferrous iron (Fe2+), which can readily been taken up by bacteria. In this application we propose to determine the molecular structures and mechanisms that enable iron acquisition in bacteria, using the cyanobacterium Synechocystis sp. PCC 6803 as a model. As iron is an essential, albeit often limiting element for all bacteria, the extracellular conversion of Fe3+ into soluble Fe2+ has enormous implications, ranging from marine primary productivity to human disease. This proposal also aims to gain fundamental structural insight into the pili-cell interface through the implementation of cutting-edge imaging approaches. In addition to addressing the role of pili in iron acquisition, our proposal may also provide crucial understanding required to employ photosynthetic bacteria in the construction of truly renewable photovoltaic devices.

Publications from Cristin

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Funding scheme:

FRIBIO2-FRIPRO forskerprosjekt, biologi

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