Project description:One of the most complex prokaryotic organelles are magnetosomes, which are formed by magnetotactic bacteria as sensors for navigation in the Earth’s magnetic field. In the alphaproteobacterium Magnetospirillum gryphiswaldense magnetosomes consist of chains of magnetite crystals (Fe3O4) that under suboxic conditions are biomineralized within membrane vesicles. To form such an intricate structure, the transcription of >30 specific structural genes clustered within the genomic magnetosome island (MAI) has to be coordinated with the expression of an as-yet unknown number of auxiliary genes encoding several generic metabolic functions. However, their global regulation and transcriptional organization in response to anoxic conditions most favorable for magnetite biomineralization are still unclear. Here, we compared transcriptional profiles of anaerobically grown magnetosome forming cells with those in which magnetosome biosynthesis has been suppressed by aerobic condition. Using whole transcriptome shotgun sequencing, we found that transcription of about 300 of the >4300 genes was significantly enhanced during magnetosome formation. The about 40 top upregulated genes are directly or indirectly linked to aerobic and anaerobic respiration (denitrification) or unknown functions. mam and mms gene clusters specifically controlling magnetosome biosynthesis were highly transcribed, but constitutively expressed irrespective of the growth condition. By Cappable-sequencing, we show that the transcriptional complexity of both the MAI and the entire genome decreased under anaerobic conditions optimal for magnetosome formation. In addition, predominant promoter structures were highly similar to sigma factor σ70 dependent promoters in other Alphaproteobacteria. Our transcriptome-wide analysis revealed that magnetite biomineralization relies on a complex interplay between generic metabolic processes such as aerobic and anaerobic respiration, cellular redox control, and the biosynthesis of specific magnetosome structures. In addition, we provide insights into global regulatory features that have remained uncharacterized in the widely studied model organism M. gryphiswaldense, including a comprehensive dataset of newly annotated transcription start sites and genome-wide operon detection as a community resource.
2022-10-19 | GSE197098 | GEO
Project description:Boosting biomethanation using magnetite nanoparticles
| PRJNA1132306 | ENA
Project description:magnetite-amended anaerobic system (bacteria)
| PRJNA659155 | ENA
Project description:magnetite-amended anaerobic system (archaea)
Project description:Deatails of the series are available in the publications Suzuki et al., The Journal of Bacteriology “Global gene expression analysis of iron-inducible genes in Magnetospirillum magneticum AMB-1”, accepted for the publication. The gene expression profiles were categorized into 5 patterns. Abstract of the publication: "feo, tpd and ftr which encode ferrous transporters were up-regulated under iron-rich conditions.The concomitant rapid iron uptake and magnetite formation suggest that these uptake systems serve as iron supply lines for magnetosome synthesis." Keywords: iron response
Project description:A Transcriptomics Approach to Study the Biocompatibility and Finding out the Potential Applications of Magnetite (Fe3O4) Nanoparticles Here in this study, we examine the molecular effects of uptake of Fe3O4 nanoparticles using a whole genome microarray study in human epithelial cancer cell line. 38 genes (55%) out of 69 downregulated genes were found to be associated with TGF-beta or BMP signaling including six genes, Id1, Id2, Id3, Caspase-9, Smad6 and SMAD7, important negative regulators of these signaling pathways involved in development and tumorigenesis.