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Comprehensive genetic dissection of the magnetosome gene island reveals the step-wise assembly of a prokaryotic organelle.

ABSTRACT: Although membrane-bounded compartments are commonly considered a unique eukaryotic characteristic, many species of bacteria have organelles. Compartmentalization is well studied in eukaryotes; however, the molecular factors and processes leading to organelle formation in bacteria are poorly understood. We use the magnetosome compartments of magnetotactic bacteria as a model system to investigate organelle biogenesis in a prokaryotic system. The magnetosome is an invagination of the cell membrane that contains a specific set of proteins able to direct the synthesis of a nanometer-sized magnetite crystal. A well-conserved region called the magnetosome island (MAI) is known to be essential for magnetosome formation and contains most of the genes previously implicated in magnetosome formation. Here, we present a comprehensive functional analysis of the MAI genes in a magnetotactic bacterium, Magnetospirillum magneticum AMB-1. By characterizing MAI deletion mutants, we show that parts of its conserved core are not essential for magnetosome biogenesis and that nonconserved genes are important for crystal formation. Most importantly, we show that the mamAB gene cluster encodes for factors important for magnetosome membrane biogenesis, for targeting of proteins to this compartment and for several steps during magnetite production. Altogether, this genetic analysis defines the function of more than a dozen factors participating in magnetosome formation and shows that magnetosomes are assembled in a step-wise manner in which membrane biogenesis, magnetosome protein localization, and biomineralization are placed under discrete genetic control.

SUBMITTER: Murat D

PROVIDER: S-EPMC2851823 | biostudies-other | 2010 Mar

REPOSITORIES: biostudies-other

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Comprehensive genetic dissection of the magnetosome gene island reveals the step-wise assembly of a prokaryotic organelle.

Murat Dorothée D Quinlan Anna A Vali Hojatollah H Komeili Arash A

Proceedings of the National Academy of Sciences of the United States of America 20100308 12

Although membrane-bounded compartments are commonly considered a unique eukaryotic characteristic, many species of bacteria have organelles. Compartmentalization is well studied in eukaryotes; however, the molecular factors and processes leading to organelle formation in bacteria are poorly understood. We use the magnetosome compartments of magnetotactic bacteria as a model system to investigate organelle biogenesis in a prokaryotic system. The magnetosome is an invagination of the cell membrane ...[more]

PMID: 20212111

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Project description:BackgroundAn epidural steroid injection (ESI) is used to treat a number of morbid central nervous system pathologies and is considered a reasonably safe procedure. This study aimed to determine the relative infection risk after spinal surgery by comparing outcomes in spinal surgery patients who received an ESI shortly prior to the surgery against those who did not receive an ESI shortly prior to the surgery.MethodsThe present study is a retrospective cohort study using a multi-institutional healthcare database, TriNetX, to collect data on patients who received spinal surgery with and without having had ESIs six months before surgery. Two cohorts were generated: Cohort 1 included patients who had received an ESI in the six months prior to spinal surgery, and cohort 2 included patients who did not have an ESI in the six months prior to spinal surgery. The patients in cohort 2 had propensity scores matched 1:1 to those in cohort 1 using common baseline demographics, comorbidities and spinal procedure indications. The spinal procedures and surgeries considered for the analysis included open procedures for any purpose, including exploration, decompression, resection, revision or biopsy. Multiple outcomes were compared across these two cohorts in the three months following the spinal procedure/surgery, including the occurrence of death, surgical site infection, epidural and/or spinal abscess, and dural tear.ResultsAn ESI in the six months prior to spinal surgery was associated with a significant decrease in the likelihood epidural/spinal abscess in the three months after surgery. There was no change in mortality, wound infection or identification of dural tear in the three months after spinal surgery for those who received an ESI six months before spinal surgery.ConclusionThis data suggests that epidural steroid injections' anti-inflammatory effects provide benefits before surgery beyond symptomatic relief. Given that the degeneration of spinal pathologies is typically advanced rather than corrected by the body's inflammatory response, it is likely that preventing hyperactivation of the body's immune system in the months preceding surgical intervention, a traumatic insult, is protective compared to no intervention and, importantly, without major adverse effects.

Dataset Information

Comprehensive genetic dissection of the magnetosome gene island reveals the step-wise assembly of a prokaryotic organelle.

Publications

Comprehensive genetic dissection of the magnetosome gene island reveals the step-wise assembly of a prokaryotic organelle.

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