There is a strong need to better diagnose infections at deep body sites through noninvasive molecular imaging methods. Herein, we describe the synthesis and characterization of probes based on siderophore conjugates with catechol moieties and a central DOTAM scaffold. The probes can accommodate a metal ion as well as an antibiotic moiety and are therefore suited for theranostic purposes. The translocation of the conjugates across the outer and inner cell membranes of E. coli was confirmed by growth recovery experiments with enterobactin-deficient strains, by the antibacterial activity of ampicillin conjugates, and by confocal imaging using a fluorogen-activating protein-malachite green system adapted to E. coli. The suitability of the probes for in vivo imaging was demonstrated with a Cy5.5 conjugate in mice infected with P. aeruginosa.

Transfer RNA (tRNA) modifications impact the structure and function of tRNAs, thus affecting the efficiency and fidelity of translation. In the opportunistic pathogen Pseudomonas aeruginosa translational regulation plays an important but less defined role in adaptation to changing environments. In this study, we have explored tRNA modifications in P. aeruginosa through LC‐MS/MS approaches. Neutral loss scanning (NLS) demonstrated the potential to identify previously unknown modifications, whereas multiple reaction monitoring (MRM) was able to detect modifications with high specificity and sensitivity. In this study, the MRM‐based external calibration method allowed for quantification of the four canonical and 32 modified ribonucleosides, out of which 21 tRNA modifications were quantified in the total tRNA pool of P. aeruginosa PA14. We also purified the single tRNA isoacceptors tRNA‐ArgUCU, tRNA‐LeuCAA, and tRNA‐TrpCCA and determined their specific modification patterns, both qualitatively and quantitatively. Deeper insights into the nature and dynamics of tRNA modifications in P. aeruginosa should pave the way for further studies on post‐transcriptional gene regulation as a relatively unexplored molecular mechanism of controlling bacterial pathogenicity and mode of growth.

Es besteht ein großer Bedarf an besseren Diagnosen von Infektionen in tieferliegenden Kçrperregionen durch nichtinvasive molekulare Bildgebung. In diesem Zusammenhang wurden Sonden entwickelt, die auf Siderophor-Konjugaten mit Catechol-Einheiten und einem zentralenD OTAM-Kern beruhen. Diese Sonden kçnnen sowohlein Metallion als auche inen antibiotischen Wirkstoff tragen und eignen sich daher fürtheranostische Anwendungen. Die Translokation der Konjugate durchd ie innere und äußere Zellmembran von E. coli wurde durch Experimente zur Wiederherstellung des Wachstums mit Enterobactin-defizienten Bakterienstämmen, durch die antibakterielle WirkungA mpicillin-tragender Konjugate sowie durch Konfokalmikroskopie bestätigt. FürL etztere wurde ein auf E. coli adaptiertes System aus Fluorogenaktivierendem Protein und Malachitgrünverwendet. Eine erste Anwendung der Verbindungen fürd ie In-vivo-Bildgebung wurde mit einem Cy5.5-Konjugat in P. -aeruginosa-infizierten Mäusen gezeigt.

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