Molecular Biology

A Microbial Mystery

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Science  12 Jan 2007:
Vol. 315, Issue 5809, pp. 163
DOI: 10.1126/science.315.5809.163a

One consequence of the widespread access to DNA sequencing machines and the accompanying proliferation of genomes and genes is a renewed focus on RNA. As the most labile and hard-to-handle biological polymer, it had been valued primarily as a carrier (messenger RNA and transfer RNA) of information or as a structural, and occasionally functional, macromolecule (ribosomal RNA). Noncoding RNAs of the micro and small interfering kinds have taken center stage recently, along with riboswitches, which exhibit small molecule-induced conformational changes that regulate gene expression.

Puerta-Fernandez et al. have identified a large noncoding RNA (approximately 600 nucleotides in length) on the basis of a sequence that is highly conserved across 15 microbes that inhabit harsh environments (defined as extremes of pH, salt, or temperature). A consensus model of secondary structure reveals conserved regions within loops and bulges, suggesting that there are likely to be functional constraints on its tertiary structure, though what this function might be is a mystery. Nearby genes do not fall into a single type of metabolic pathway, but immediately downstream in 14 out of the 15 bacterial genomes is a putative membrane protein that may form a complex with this enigmatic RNA. — GJC

Proc. Natl. Acad. Sci. U.S.A. 103, 19490 (2006).

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