Chromosomal structure of the halophilic archaebacterium Halobacterium salinarium.
AUTOR(ES)
Takayanagi, S
RESUMO
The chromosomal structure of the extremely halophilic archaebacterium Halobacterium salinarium was examined. Sheared chromosomes prepared from the bacteria in the late exponential phase were separated into two peaks (peaks I and II) by sucrose gradient centrifugation, suggesting that the chromosomes consist of two parts differing in quality. The UV spectra of peaks I and II resembled those of DNA and eukaryotic chromatin, respectively. Electron microscopic observations revealed that the major component of peak I was protein-free DNA, while the major components of peak II were rugged thick fibers with a diameter of 17 to 20 nm. The rugged fibers basically consisted of bacterial nucleosome-like structures composed of DNA and protein, as demonstrated in experiments with proteinase and nuclease digestion. Whole-mount electron microscopic observations of the chromosomes directly spread onto a water surface revealed a configuration in which the above-described regions were localized on a continuous DNA fiber. From these results it is concluded that the H. salinarium chromosome is composed of regions of protein-free DNA and DNA associated with nucleosome-like structures. Peaks I and II were predominant in the early exponential phase and stationary phase, respectively; therefore, the transition of the chromosome structure between non-protein-associated and protein-associated forms seems to be related to the bacterial growth phase.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=207413Documentos Relacionados
- Nucleosomelike structures associated with chromosomes of the archaebacterium Halobacterium salinarium.
- Halophilic enzymes in cell-free extracts of Halobacterium salinarium.
- Conservation of chromosomal arrangement among three strains of the genetically unstable archaeon Halobacterium salinarium.
- Structure specific ds/ss-RNase activity in the extreme halophile Halobacterium salinarium.
- Primary structure and functional analysis of the soluble transducer protein HtrXI in the archaeon Halobacterium salinarium.