First Complete 3-D Structure of a Bacterial Chromosome

A team of researchers at the University of Massachusetts Medical School, Harvard Medical School, Stanford University, and the Prince Felipe Research Centre in Spain have deciphered the complete three-dimensional (3-D) structure of the bacterium Caulobacter crescentus's chromosome. Analysis of the resulting structure —published this week in the October 21, 2011 issue of Molecular Cell — has revealed new insights into the function of genetic sequences responsible for the shape and structure of this genome. Scientists know that the 3-D shape of a cell's chromosome plays a role in how genetic sequences and genes are regulated. However, technical challenges have limited genome-wide analysis of a chromosome's architecture that would allow for simultaneous identification of the elements involved in shaping it and analysis of specific features of the structure. In this study, researchers used high-throughput chromatin interaction detection; next-generation DNA sequencing; computational modeling; and fluorescent microscopy to build the first 3-D model of the architecture of the bacterium's chromosome and analyze the resulting structures. This new experimental approach revealed novel characteristics of a specific genetic sequence called the parS site, which helps to define the chromosome's shape. "What we've shown is that it's possible to combine molecular biology with 3-D modeling technology to perform studies that tell us novel things about how genomes fold and identify the genetic sequences that are responsible," said Dr. Job Dekker, a pioneer in chromosome interaction detection technologies, professor of biochemistry & molecular pharmacology at the University of Massachusetts Medical School, and one of the authors of the study. Dr.
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