Chromosome organization by a nucleoid-associated protein in live bacteria.

Wenqin Wang, Gene-Wei Li, Chongyi Chen, X Sunney Xie, Xiaowei Zhuang

Department of Physics, Harvard University, Cambridge, MA 02138, USA.

Science (New York, N.Y.) 2011 Sep 9

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Bacterial chromosomes are confined in submicrometer-sized nucleoids. Chromosome organization is facilitated by nucleoid-associated proteins (NAPs), but the mechanisms of action remain elusive. In this work, we used super-resolution fluorescence microscopy, in combination with a chromosome-conformation capture assay, to study the distributions of major NAPs in live Escherichia coli cells. Four NAPs--HU, Fis, IHF, and StpA--were largely scattered throughout the nucleoid. In contrast, H-NS, a global transcriptional silencer, formed two compact clusters per chromosome, driven by oligomerization of DNA-bound H-NS through interactions mediated by the amino-terminal domain of the protein. H-NS sequestered the regulated operons into these clusters and juxtaposed numerous DNA segments broadly distributed throughout the chromosome. Deleting H-NS led to substantial chromosome reorganization. These observations demonstrate that H-NS plays a key role in global chromosome organization in bacteria.

Citation

Wenqin Wang, Gene-Wei Li, Chongyi Chen, X Sunney Xie, Xiaowei Zhuang. Chromosome organization by a nucleoid-associated protein in live bacteria. Science (New York, N.Y.). 2011 Sep 9;333(6048):1445-9