The Poly-Histidine Tag H6 Mediates Structural and Functional Properties of Disintegrating, Protein-Releasing Inclusion Bodies

SÁNCHEZ, JULIETA MARÍA; CARRATALÁ, JOSÉ VICENTE; SERNA, NAROA; UNZUETA, UGUTZ; NOLAN, VERÓNICA; SÁNCHEZ-CHARDI, ALEJANDRO; VOLTÀ-DURÁN, ERIC; LÓPEZ-LAGUNA, HÈCTOR; FERRER-MIRALLES, NEUS; VILLAVERDE, ANTONIO; VAZQUEZ, ESTHER

Pharmaceutics

MDPI

Año: 2022 vol. 14

The coordination between histidine-rich peptides and divalent cations supports the formationof nano- and micro-scale protein biomaterials, including toxic and non-toxic functional amyloids,which can be adapted as drug delivery systems. Among them, inclusion bodies (IBs) formed inrecombinant bacteria have shown promise as protein depots for time-sustained protein release. Wehave demonstrated here that the hexahistidine (H6) tag, fused to recombinant proteins, impacts bothon the formation of bacterial IBs and on the conformation of the IB-forming protein, which showsa higher content of cross-beta intermolecular interactions in H6-tagged versions. Additionally, theaddition of EDTA during the spontaneous disintegration of isolated IBs largely affects the proteinleakage rate, again protein release being stimulated in His-tagged materials. This event depends onthe number of His residues but irrespective of the location of the tag in the protein, as it occurs ineither C-tagged or N-tagged proteins. The architectonic role of H6 in the formation of bacterial IBs,probably through coordination with divalent cations, offers an easy approach to manipulate proteinleakage and to tailor the applicability of this material as a secretory amyloidal depot in differentbiomedical interfaces. In addition, the findings also offer a model to finely investigate, in a simpleset-up, the mechanics of protein release from functional secretory amyloids.