The Division of Endosymbiotic Organelles

Osteryoung, Katherine W.; Nunnari, Jodi

doi:10.1126/science.1082192

Cited by 273 publications

(236 citation statements)

References 77 publications

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“…NbGyrA, NbGyrB, and other plant DNA gyrase subunits contain an N-terminal extension that features chloroplast and mitochondria targeting signals (Emanuelsson and von Heijne, 2001). Of the prokaryotic GyrA and GyrB sequences, those of cyanobacterial species are most closely related to NbGyrA and NbGyrB (50 to 61% sequence identity), which suggests that the plant GyrA and GyrB genes have an endosymbiotic origin (Osteryoung and Nunnari, 2003).…”

Section: N Benthamiana Homologs Of the Dna Gyrase A And B Subunitsmentioning

confidence: 97%

DNA Gyrase Is Involved in Chloroplast Nucleoid Partitioning

et al. 2004

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DNA gyrase, which catalyzes topological transformation of DNA, plays an essential role in replication and transcription in prokaryotes. Virus-induced gene silencing of NbGyrA or NbGyrB, which putatively encode DNA gyrase subunits A and B, respectively, resulted in leaf yellowing phenotypes in Nicotiana benthamiana. NbGyrA and NbGyrB complemented the gyrA and gyrB temperature-sensitive mutations of Escherichia coli, respectively, which indicates that the plant and bacterial subunits are functionally similar. NbGyrA and NbGyrB were targeted to both chloroplasts and mitochondria, and depletion of these subunits affected both organelles by reducing chloroplast numbers and inducing morphological and physiological abnormalities in both organelles. Flow cytometry analysis revealed that the average DNA content in the affected chloroplasts and mitochondria was significantly higher than in the control organelles. Furthermore, 49,6-diamidino-2-phenylindole staining revealed that the abnormal chloroplasts contained one or a few large nucleoids instead of multiple small nucleoids dispersed throughout the stroma. Pulse-field gel electrophoresis analyses of chloroplasts demonstrated that the sizes and/ or structure of the DNA molecules in the abnormal chloroplast nucleoids are highly aberrant. Based on these results, we propose that DNA gyrase plays a critical role in chloroplast nucleoid partitioning by regulating DNA topology.

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Section: N Benthamiana Homologs Of the Dna Gyrase A And B Subunitsmentioning

confidence: 97%

DNA Gyrase Is Involved in Chloroplast Nucleoid Partitioning

et al. 2004

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“…In the following section we will review the fission/fusion machinery focusing on the proteins that have been shown to be involved in mammalian cell death (Table 1). For a more detailed discussion of mitochondrial fission/fusion machinery see review [34][35][36][37][38][39][40].…”

Section: Overview Of Mitochondrial Membrane Dynamics Machinementioning

confidence: 99%

Mitochondrial dynamics in the regulation of neuronal cell death

2007

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Mitochondria undergo continuous fission and fusion events in physiological situations. Fragmentation of mitochondria during cell death has been shown to play a key role in cell death progression, including release of the mitochondrial apoptotic proteins. Ultrastructural changes in mitochondria, such as cristae remodeling, is also involved in cell death initiation. Here, we emphasize the important role of mitochondrial fission/fusion machinery in neuronal cell death. Unlike many other cell types such as immortalized cell lines, neurons are distinct morphologically and functionally. We will discuss how this uniqueness presents special challenges in the cellular response to neurotoxic stresses, and how this affects the mitochondrial dynamics in the regulation of cell death in neurons.

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“…These processes require nuclear-encoded assembly factors (Grivell et al, 1999;Vothknecht and Westhoff, 2001). (v) Organelle development, for instance organelle division, which is tightly controlled by nuclear-encoded proteins (Osteryoung and Nunnari, 2003).…”

Section: Anterograde Mechanismsmentioning

confidence: 99%

Genomics-based dissection of the cross-talk of chloroplasts with the nucleus and mitochondria in Arabidopsis

Leister¹

2005

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Post-endosymbiotic evolution of chloroplasts was characterized by a massive transfer of cyanobacterial genes to the nucleus, followed by re-routing of many of their encoded proteins. In consequence, most plastid proteins are nucleus-encoded, enabling an anterograde (nucleusto-plastid) control of the organelle. The regulation of chloroplast functions includes also cross-talk between chloroplasts and mitochondria, as well as retrograde (plastid-to-nucleus) signalling. Genetic analyses reveal that redox state, flux through the chlorophyll biosynthetic pathway, sugar sensing and reactive oxygen species contribute to retrograde signalling. However, the identity of the messenger molecule(s) remains largely unknown. Novel facets of the chloroplast -mitochondrion cross-talk have been revealed by the characterization of mitochondrial mutants affected in chloroplast properties. Studies of the nuclear chloroplast transcriptome imply the existence of at least three distinct types of transcriptional regulation: a master switch, acting in a binary mode by either inducing or repressing the same large set of genes; a ''mixed response'' with about equal numbers of up-and down-regulated genes; and mechanisms supporting the specific co-regulation of nuclear genes for photosynthesis and for plastid gene expression. The recent discovery of the latter mode of control highlights a possibly ancient route to co-ordinate chloroplast and nuclear genome expression. D

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The Division of Endosymbiotic Organelles

Cited by 273 publications

References 77 publications

DNA Gyrase Is Involved in Chloroplast Nucleoid Partitioning

DNA Gyrase Is Involved in Chloroplast Nucleoid Partitioning

Mitochondrial dynamics in the regulation of neuronal cell death

Genomics-based dissection of the cross-talk of chloroplasts with the nucleus and mitochondria in Arabidopsis

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