The cellular equivalent of a rough wiring diagram for HIV gives further evidence that the architecture of its genome, not just its sequence, explains how the deadly virus works.
Researchers at the University of North Carolina used chemical compounds that linked to pieces of HIV's genome to trace its shape and arrangement. Their morphological reverse-engineering was necessary because HIV stymies standard atomic-level microscopes.
Unlike most genomes, the genetic code of HIV is made from single-stranded RNA rather than double-stranded DNA. Its units are small, densely packed and very hard to work with. As a result, though scientists have identified HIV's genes and their order, just one-fifth of its genome has been described in precise spatial detail.
That's important because genomes don't look anything like the neatly linear, bar code-like pictures returned by basic sequencing techniques. In reality, genomes are arranged in intricate, three-dimensional loops and whorls. And just as a list of machines isn't very useful without a description of their arrangement on a factory floor, structure matters.
In a commentary accompanying the findings, published Wednesday in Nature, University of Michigan chemist Hashim Al-Hashimi called them an "aerial view." The map is still not complete or truly high-resolution. It's also a one-time representation of an ever-shifting target. But even so, it's detailed enough to suggest that the architecture of certain spots in the HIV genome's middle regions coordinates protein manufacture.
Until now, high-resolution imaging efforts have focused on the genome's tips. Researchers can now target other regions in greater detail, and perhaps see where a wrench might be thrown into the viral assembly line. "The quest for a high-resolution structure of the entire HIV-1 RNA genome has begun in earnest," writes Hashimi.
See Also:
- To Understand the Blueprint of Life, Crumple It
- A New Tactic Against HIV: T-Cell Tweaks
- Scientists Record The Birth of a Virus
Citations: "Architecture and secondary structure of an entire HIV-1 RNA genome." By Joseph M. Watts, Kristen K. Dang, Robert J. Gorelick, Christopher W. Leonard, Julian W. Bess Jr,
Ronald Swanstrom, Christina L. Burch & Kevin M. Weeks. Nature Vol. 460 No. 7256, August 6, 2009.
*"Aerial view of the HIV genome." By Hashim M. Al-Hashimi. Nature Vol. 460 No. 7256, August 6, 2009. *
*Image: Nature
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