Engineered bacteria for targeted bacterial killing; plus Cas12a base editors, base editing to restore hearing and more

Targeted delivery of antibacterial toxins
University of Washington researchers have co-opted a bacterial secretion system to enable killing of select bacterial species. They described in Cell Host & Microbe how they programmed bacteria with a Type VI secretion system (T6SS) -- which some Gram-negative species use to inject toxins into other bacterial cells -- to express nanobodies against a bacterial target. The single-domain antibodies promote predator-prey adhesion and antibacterial toxin delivery. The engineered cells, named PICs (programmed inhibitor cells), expand the toolbox for targeted antimicrobials beyond bacteriophage therapies (see “Sparing the Microbiome”).

Cas12a base editors
In Cell Reports, ShanghaiTech University and Chinese Academy of Sciences researchers described a Cas12a base editing system dubbed BEACON (base editing induced by human APOBEC3A and Cas12a without DNA break). The BEACON editors, fusions between an engineered human APOBEC3A and deactivated Cas12a, edited cultured cells with efficiencies comparable to or better than two Cas9-based editors. In 10 mouse embryos successfully edited with BEACON, the editing efficiencies were 17-57%; in two mice derived from additional edited embryos, the editing frequencies were 23% and 57%...