First direct evidence for direct cell-membrane penetrations of polycationic homopoly(amino acid)s produced by bacteria


Takeuchi Yamato,Ushimaru Kazunori,Kaneda Kohei,Maruyama Chitose,Ito Takashi,Yamanaka Kazuya,Ogasawara YasushiORCID,Katano Hajime,Kato Yasuo,Dairi TohruORCID,Hamano YoshimitsuORCID


AbstractBacteria produce polycationic homopoly(amino acid)s, which are characterized by isopeptide backbones. Although the biological significance of polycationic homopoly(amino acid)s remains unclear, increasing attention has recently been focused on their potential use to achieve cellular internalization. Here, for the first time, we provide direct evidence that two representative bacterial polycationic isopeptides, ε-poly-l-α-lysine (ε-PαL) and ε-oligo-l-β-lysine (ε-OβL), were internalized into mammalian cells by direct cell-membrane penetration and then diffused throughout the cytosol. In this study, we used clickable ε-PαL and ε-OβL derivatives carrying a C-terminal azide group, which were enzymatically produced and then conjugated with a fluorescent dye to analyze subcellular localization. Interestingly, fluorescent proteins conjugated with the clickable ε-PαL or ε-OβL were also internalized into cells and diffused throughout the cytosol. Notably, a Cre recombinase conjugate with ε-PαL entered cells and mediated the Cre/loxP recombination, and ε-PαL was found to deliver a full-length IgG antibody to the cytosol and nucleus.


MEXT | Japan Society for the Promotion of Science

Japan Foundation for Applied Enzymology

Nagase Science Technology Foundation

Amano Enzyme Foundation


Springer Science and Business Media LLC


General Agricultural and Biological Sciences,General Biochemistry, Genetics and Molecular Biology,Medicine (miscellaneous)







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