A new bioinformatic approach for discovering biologically active small molecules encoded in the human microbiome is described in Science this week. Called MetaBGC — short for metagenomic identifier of biosynthetic gene clusters — the method is based on a novel computational algorithm that detects biosynthetic gene clusters de novo from metagenomic sequencing data. MetaBGC's developers use the method to show that members of a clinically used class of molecules are widely encoded in the human microbiome and that they exert potent antibacterial activities against neighboring microbes. This, they write, implies a possible role in niche competition and host defense. "We see this strategy as a systematic one for unveiling the chemical repertoire encoded by the human microbiome, a much-needed step for understanding its role in human health and disease," the authors write.
A team of Ludwig Maximilian University scientists report a single chemical pathway is capable of generating both purine and pyrimidine nucleosides, the building blocks of RNA, offering new clues about the origin of life on Earth. While it is theorized that life started with RNAs that were able to self-recognize and replicate, it was unclear how RNA was created under prebiotic conditions. In their study, which appears in Science, the investigators demonstrate the synthesis of the pyrimidine nucleosides from small molecules and ribose, driven solely by wet-dry cycles. "In the presence of phosphate-containing minerals, 5'-mono- and diphosphates also form selectively in one-pot reactions," they write. "The pathway is compatible with purine synthesis, allowing the concurrent formation of all Watson-Crick bases."