Paramagnetospirillum magneticum AMB-1
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ABSTRACT:
PROVIDER: PRJNA16217 | ENA |
REPOSITORIES: ENA
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Project description:Iron is limiting in the environment, bacteria respond to this deprivation by activating genes required for bacterial iron homeostasis. Transcriptional regulation in response to iron in Gram-negative bacteria is largely mediated by the ferric uptake regulator protein Fur, which in the presence of iron binds to a specific sequence in the promoter regions of genes under its control and acts as a repressor. Here we describe comparative global gene expression analysis using DNA microarray based on the whole genome sequence of the magnetotactic bacterium Magnetospirillum magneticum AMB-1 was conducted between wild type strain and a non-magnetic NMA61 mutant strain, generated by mini-Tn5 transposon mutagenesis which is incapable of assimilating iron to cytoplasm. No induction of the fur genes in NMA61 mutant strain was considered to be due to low intracellular iron concentration. In the iron-replete condition, among 4492 genes, 434 genes were down-regulated and 527 genes were up-regulated in the wild type strain. Among 434 genes down-regulated, 299 genes were not down-regulated in NMA61 mutant strain, indicating these genes are candidates of Fur-regulated. Keywords: Iron, magnetotactic bacteria
2007-07-07 | GSE5832 | GEO
Project description:Identification of Iron-Inducible Genes in Magnetospirillum magneticum AMB-1 Non-Magnetic Mutant
| PRJNA97227 | ENA
Project description:Expression analysis of Magnetospirillum magneticum AMB-1 WT, ΔMAI, ΔctrA, ΔdivK, and ΔctrA complemented with CtrA D51E, CtrA D51A, and an empty vector control
| PRJNA152467 | ENA
Project description:Global gene expression analysis of iron-inducible genes in Magnetospirillum magneticum AMB-1
| PRJNA94169 | ENA
Project description:Iron is limiting in the environment, bacteria respond to this deprivation by activating genes required for bacterial iron homeostasis. Transcriptional regulation in response to iron in Gram-negative bacteria is largely mediated by the ferric uptake regulator protein Fur, which in the presence of iron binds to a specific sequence in the promoter regions of genes under its control and acts as a repressor. Here we describe comparative global gene expression analysis using DNA microarray based on the whole genome sequence of the magnetotactic bacterium Magnetospirillum magneticum AMB-1 was conducted between wild type strain and a non-magnetic NMA61 mutant strain, generated by mini-Tn5 transposon mutagenesis which is incapable of assimilating iron to cytoplasm. No induction of the fur genes in NMA61 mutant strain was considered to be due to low intracellular iron concentration. In the iron-replete condition, among 4492 genes, 434 genes were down-regulated and 527 genes were up-regulated in the wild type strain. Among 434 genes down-regulated, 299 genes were not down-regulated in NMA61 mutant strain, indicating these genes are candidates of Fur-regulated. A non-magnetic mutant of Magnetospirillum magneticum AMB-1 (NMA61) generated transposon mutagenesis was grown under various iron conditions. Global gene expression analysis of iron-inducible genes was conducted by using DNA microarray.
2010-07-01 | E-GEOD-5832 | biostudies-arrayexpress
Project description:Magnetospirillum magneticum overview
| PRJNA39447 | ENA
Project description:The mechanism of how magnetotactic bacteria navigate along the magnetic field has been a puzzle. Two main models disagree on whether the magnetotactic behavior results from passive alignment with the magnetic field or active sensing of the magnetic force. Here, we quantitatively studied the swimming patterns of Magnetospirillum magneticum AMB-1 cells to understand the origin of their magnetotactic behaviors. Single-cell tracking and swimming pattern analysis showed that the cells follow a mixed run-reverse-tumble pattern. The average run time decreased with the angle between the cell's moving velocity and the external magnetic field. For mutant cells without the methyl-accepting chemotaxis protein (MCP) Amb0994, such dependence disappeared and bacteria failed to align with magnetic field lines. This dysfunction was recovered by complementary Amb0994 on a plasmid. At high magnetic field (>5 mT), all strains with intact magnetosome chains (including the ?amb0994-0995 strains) showed alignment with the external magnetic field. These results suggested that the mechanism for magnetotaxis is magnetic field dependent. Due to the magnetic dipole moment of the cell, the external magnetic field exerts a torque on the cell. In high magnetic fields, this torque is large enough to overcome the random re-orientation of the cell, and the cells align passively with the external magnetic field, much like a compass. In smaller (and biologically more relevant) external fields, the external force alone is not strong enough to align the cell mechanically. However, magnetotactic behaviors persist due to an active sensing mechanism in which the cell senses the torque by Amb0994 and actively regulates the flagella bias accordingly to align its orientation with the external magnetic field. Our results reconciled the two putative models for magnetotaxis and revealed a key molecular component in the underlying magneto-sensing pathway.
| S-EPMC4134682 | biostudies-literature
Project description:Investigation of whole genome expression changes in Magnetospririllum magneticum mutants, probing the role of the CtrA regulatory pathway. The mutants are further described in a manuscript submitted for publication at J. Bacteriology. Developmental events across the prokaryotic life cycle are highly regulated at the transcriptional and post-translational levels. Key elements of a few regulatory networks are conserved among phylogenetic groups of bacteria, although the features controlled by these conserved systems are as diverse as the organisms encoding them. In this work, we probe the role of the CtrA regulatory network, conserved throughout the Alphaproteobacteria, in the magnetotactic bacterium, Magnetospirillum magneticum strain AMB-1, which possesses unique intracellular organization and compartmentalization. While we show that CtrA in AMB-1 is not essential for viability, it is required for motility, and its putative phosphorylation state dictates the ability of CtrA to activate the flagella biosynthesis gene cascade. Gene expression analysis of strains expressing active and inactive CtrA alleles point to the composition of the extended CtrA regulon, including both direct and indirect targets. These results, combined with a bioinformatic study of the AMB-1 genome, enabled the prediction of an AMB-1 specific CtrA binding site. Further, phylogenetic studies comparing CtrA sequences from Alphaproteobacteria in which the role of CtrA has been experimentally examined reveals an ancestral role of CtrA in the regulation of motility and suggests that its essential functions in other Alphaproteobacteria were acquired subsequently.
2012-02-17 | GSE35625 | GEO
Project description:Investigation of whole genome expression changes in Magnetospririllum magneticum mutants, probing the role of the CtrA regulatory pathway. The mutants are further described in a manuscript submitted for publication at J. Bacteriology. Developmental events across the prokaryotic life cycle are highly regulated at the transcriptional and post-translational levels. Key elements of a few regulatory networks are conserved among phylogenetic groups of bacteria, although the features controlled by these conserved systems are as diverse as the organisms encoding them. In this work, we probe the role of the CtrA regulatory network, conserved throughout the Alphaproteobacteria, in the magnetotactic bacterium, Magnetospirillum magneticum strain AMB-1, which possesses unique intracellular organization and compartmentalization. While we show that CtrA in AMB-1 is not essential for viability, it is required for motility, and its putative phosphorylation state dictates the ability of CtrA to activate the flagella biosynthesis gene cascade. Gene expression analysis of strains expressing active and inactive CtrA alleles point to the composition of the extended CtrA regulon, including both direct and indirect targets. These results, combined with a bioinformatic study of the AMB-1 genome, enabled the prediction of an AMB-1 specific CtrA binding site. Further, phylogenetic studies comparing CtrA sequences from Alphaproteobacteria in which the role of CtrA has been experimentally examined reveals an ancestral role of CtrA in the regulation of motility and suggests that its essential functions in other Alphaproteobacteria were acquired subsequently. Total RNA was recovered from each of the wild-type and mutant strains, reverse transcribed to cDNA, fluorescently labeled, and hybridized to whole genome microarrays. The arrays contain 7 probes/gene, with the entire genome duplicated twice. In addition, the arrays contain 7 probes for 22 unannotated ORFs and tiling of a genomic region from coordinates 977403-1097027.
2012-02-17 | E-GEOD-35625 | biostudies-arrayexpress