Responses of hyperthermophilic crenarchaea to UV irradiation

Götz, Dorothee; Paytubi, Sònia; Munro, Stacey; Lundgren, Magnus; Bernander, Rolf; White, Malcolm F.

doi:10.1186/gb-2007-8-10-r220

Cited by 108 publications

(171 citation statements)

References 52 publications

(64 reference statements)

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“…The levels of anucleate cells are comparable to those reported for C. crescentus, wherein increased levels of ParA or ParAB resulted in 5% and 10% of anucleate cells, respectively (9). Interestingly, segAB are highly repressed upon UV irradiation (27). This is consistent with a role in chromosome segregation, as genome replication, partition, and cell division are put on hold until DNA damage is repaired.…”

Section: Discussionsupporting

confidence: 74%

Chromosome segregation in Archaea mediated by a hybrid DNA partition machine

Kalliomaa-Sanford

Rodríguez-Castañeda²,

McLeod³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Eukarya and, more recently, some bacteria have been shown to rely on a cytoskeleton-based apparatus to drive chromosome segregation. In contrast, the factors and mechanisms underpinning this fundamental process are underexplored in archaea, the third domain of life. Here we establish that the archaeon Sulfolobus solfataricus harbors a hybrid segrosome consisting of two interacting proteins, SegA and SegB, that play a key role in genome segregation in this organism. SegA is an ortholog of bacterial, Walker-type ParA proteins, whereas SegB is an archaea-specific factor lacking sequence identity to either eukaryotic or bacterial proteins, but sharing homology with a cluster of uncharacterized factors conserved in both crenarchaea and euryarchaea, the two major archaeal sub-phyla. We show that SegA is an ATPase that polymerizes in vitro and that SegB is a site-specific DNA-binding protein contacting palindromic sequences located upstream of the segAB cassette. SegB interacts with SegA in the presence of nucleotides and dramatically affects its polymerization dynamics. Our data demonstrate that SegB strongly stimulates SegA polymerization, possibly by promoting SegA nucleation and accelerating polymer growth. Increased expression levels of segAB resulted in severe growth and chromosome segregation defects, including formation of anucleate cells, compact nucleoids confined to one half of the cell compartment and fragmented nucleoids. The overall picture emerging from our findings indicates that the SegAB complex fulfills a crucial function in chromosome segregation and is the prototype of a DNA partition machine widespread across archaea.nucleoid | polymerization | segrosome | Sulfolobus | Walker-type ParA

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Section: Discussionsupporting

confidence: 74%

Chromosome segregation in Archaea mediated by a hybrid DNA partition machine

Kalliomaa-Sanford

Rodríguez-Castañeda²,

McLeod³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…5), whereas cells arrested by acetate showed elevated levels of Orc1-2 and low levels of Orc1-1 and Orc1-3 (1); resumption of growth after arrest resulted in elevated Orc1-1 and -3 and greatly reduced Orc1-2. Several laboratories have reported microarray analyses of the response of the Sulfolobus transcriptome to a range of physiological stresses such as UV treatment, viral infection, and heat shock (21)(22)(23)(24). Interestingly, these studies have revealed modulation of Orc1 gene transcript and/or protein levels; similar to that seen with microarray analysis of acetate-treated cells (25).…”

Section: Discussionsupporting

confidence: 48%

Chromosome replication dynamics in the archaeon Sulfolobus acidocaldarius

Duggin

McCallum

Bell

2008

Proc. Natl. Acad. Sci. U.S.A.

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The ''baby machine'' provides a means of generating synchronized cultures of minimally perturbed cells. We describe the use of this technique to establish the key cell-cycle parameters of hyperthermophilic archaea of the genus Sulfolobus. The 3 DNA replication origins of Sulfolobus acidocaldarius were mapped by 2D gel analysis to near 0 (oriC2), 579 (oriC1), and 1,197 kb (oriC3) on the 2,226-kb circular genome, and we present a direct demonstration of their activity within the first few minutes of a synchronous cell cycle. We also detected X-shaped DNA molecules at the origins in log-phase cells, but these were not directly associated with replication initiation or ongoing chromosome replication in synchronized cells. Whole-genome marker frequency analyses of both synchronous and log-phase cultures showed that origin utilization was close to 100% for all 3 origins per round of replication. However, oriC2 was activated slightly later on average compared with oriC1 and oriC3. The DNA replication forks moved bidirectionally away from each origin at Ϸ88 bp per second in synchronous culture. Analysis of the 3 Orc1/Cdc6 initiator proteins showed a uniformity of cellular abundance and origin binding throughout the cell cycle. In contrast, although levels of the MCM helicase were constant across the cell cycle, its origin localization was regulated, because it was strongly enriched at all 3 origins in early S phase.Archaea ͉ cell cycle ͉ DNA replication

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“…These public data sets included 108 Mmp microarrays for a mutant of Ehb membrane-associated hydrogenase (Porat et al 2006), different growth rates, and growth under limiting hydrogen, phosphate, and leucine (Hendrickson et al 2007(Hendrickson et al , 2008; 55 Pfu microarrays for growth under gamma radiation (Williams et al 2007), elemental sulfur (Schut et al 2007), hydrogen peroxide (Strand et al 2010), cold shock , and different carbon sources of peptides and maltose (Schut et al 2003); and 54 Sso microarrays for infection by turreted icosahedral virus (Ortmann et al 2008), growth under different oxygen concentrations (Simon et al 2009), and UV radiation (Gotz et al 2007). The conditional operons were estimated by integrating these public data with those from this study as described in Koide et al (2009).…”

Section: Identification Of Conditional Operonsmentioning

confidence: 99%

Parallel evolution of transcriptome architecture during genome reorganization

et al. 2011

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Assembly of genes into operons is generally viewed as an important process during the continual adaptation of microbes to changing environmental challenges. However, the genome reorganization events that drive this process are also the roots of instability for existing operons. We have determined that there exists a statistically significant trend that correlates the proportion of genes encoded in operons in archaea to their phylogenetic lineage. We have further characterized how microbes deal with operon instability by mapping and comparing transcriptome architectures of four phylogenetically diverse extremophiles that span the range of operon stabilities observed across archaeal lineages: a photoheterotrophic halophile (Halobacterium salinarum NRC-1), a hydrogenotrophic methanogen (Methanococcus maripaludis S2), an acidophilic and aerobic thermophile (Sulfolobus solfataricus P2), and an anaerobic hyperthermophile (Pyrococcus furiosus DSM 3638). We demonstrate how the evolution of transcriptional elements (promoters and terminators) generates new operons, restores the coordinated regulation of translocated, inverted, and newly acquired genes, and introduces completely novel regulation for even some of the most conserved operonic genes such as those encoding subunits of the ribosome. The inverse correlation (r = -0.92) between the proportion of operons with such internally located transcriptional elements and the fraction of conserved operons in each of the four archaea reveals an unprecedented view into varying stages of operon evolution. Importantly, our integrated analysis has revealed that organisms adapted to higher growth temperatures have lower tolerance for genome reorganization events that disrupt operon structures.

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Responses of hyperthermophilic crenarchaea to UV irradiation

Cited by 108 publications

References 52 publications

Chromosome segregation in Archaea mediated by a hybrid DNA partition machine

Chromosome segregation in Archaea mediated by a hybrid DNA partition machine

Chromosome replication dynamics in the archaeon Sulfolobus acidocaldarius

Parallel evolution of transcriptome architecture during genome reorganization

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