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[Jon Moulton]

Knockdowns in Gram+ bacteria (Bacillus and Enterococcus) and Gram- bacteria (Escherichia) are reported using peptide-Morpholino conjugates which activated mRNA cleavage by RNase-P. The oligos were mixed with Luria broth; no other cytosolic delivery method was required. Doses as low as 15 uM of peptide-Morpholino conjugates targeting the gyrA mRNA decreased Bacillus subtilis survival to 1.5% of control cultures after 4 hours treatment; scrambled sequence peptide-Morpholino conjugates decreased Bacillus subtilis survival to 10% of control cultures, so there was some nonspecific toxicity. This is the first report I have seen that shows a Morpholino oligo can act like a external guide strand (EGS) and trigger RNase-P activity.

Significantly, this work shows that peptide-conjugated Morpholinos can cross the Gram + cell envelope and enter the cytosol of Gram + bacteria.

Shen N, Ko JH, Xiao G, Wesolowskia D, Shan G, Geller B, Izadjood M, Altman S. Inactivation of expression of several genes in a variety of bacterial species by EGS technology. Proc. Natl. Acad. Sci. USA. 2009 April [Epub ahead of print]