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Nanoscale biological materials formed by the assembly of defined block-domain proteins control the formation of cellular compartments such as organelles. Here, we introduce an approach to intentionally 'program' the de novo synthesis and self-assembly of genetically encoded amphiphilic proteins to form cellular compartments, or organelles, in Escherichia coli. These proteins serve as building blocks for the formation of artificial compartments in vivo in a similar way to lipid-based organelles. We investigated the formation of these organelles using epifluorescence microscopy, total internal reflection fluorescence microscopy and transmission electron microscopy. The in vivo modification of these protein-based de novo organelles, by means of site-specific incorporation of unnatural amino acids, allows the introduction of artificial chemical functionalities. Co-localization of membrane proteins results in the formation of functionalized artificial organelles combining artificial and natural cellular function. Adding these protein structures to the cellular machinery may have consequences in nanobiotechnology, synthetic biology and materials science, including the constitution of artificial cells and bio-based metamaterials.

The antimicrobial activity of poly(2-methyl-1,3-oxazoline)s (PMOX) with the antimicrobial N,N-dimethyldodecylammonium (DDA) end group is greatly dependent on the nature of the group at the distal end of the polymer, the satellite group. Three comparable PMOX with a DDA end group and different satellite groups (methyl, decyl, hexadecyl) were investigated with respect to the reasons for the huge differences in their biocidal behavior. Static light scattering (SLS) and pulsed field gradient diffusion NMR measurements revealed that the samples show comparable aggregation conduct, thus, not being responsible for the varying biological activity. Experiments using different liposomal systems as models for bacterial cell membranes have been performed. It was found that differential interactions between the respective polymers and the phospholipid membranes constitute the reason for the varying effectiveness observed in antimicrobial susceptibility determinations.

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These are important milestones in the development of an intracellular bacteriophage therapy that might be useful in the fight against multi-drug-resistant intracellular pathogens like Mycobacterium tuberculosis.