The emergence of antibiotic-resistant bacteria is a major public health threat, and therefore novel antimicrobial targets and strategies are urgently needed. In this regard, cell-wall-associated proteases are envisaged as interesting antimicrobial targets due to their role in cell wall remodeling. Here, we describe the discovery and characteristics of a protease substrate that is processed by a bacterial cell-wall-associated protease. Stationary-phase grown Gram-positive bacteria were incubated with fluorogenic protease substrates, and their cleavage and covalent incorporation into the cell wall was analyzed. Of all of the substrates used, only one substrate, containing a valine-leucine-lysine (VLK) motif, was covalently incorporated into the bacterial cell wall. Linkage of the VLK-peptide substrate appeared unrelated to sortase A and B activity, as both wild-type and sortase A and B knock out Staphylococcus aureus strains incorporated this substrate into their cell wall with comparable efficiency. Additionally, the VLK-peptide substrate showed significantly higher incorporation in the cell wall of VanA-positive Enterococcus faecium strains than in VanB- and vancomycin-susceptible isolates. In conclusion, the VLK-peptide substrate identified in this study shows promise as a vehicle for targeting antimicrobial compounds and diagnostic contrast agents to the bacterial cell wall.,
Bioconjugate Chemistry
Department of Medical Microbiology and Infectious Diseases

Hansenová Maňásková, S., Bikker, F., Nazmi, K., Van Zuidam, R. (Rianne), Slotman, J. A., van Cappellen, G., … Kaman, W. (2016). Incorporation of a Valine-Leucine-Lysine-Containing Substrate in the Bacterial Cell Wall. Bioconjugate Chemistry, 27(10), 2418–2423. doi:10.1021/acs.bioconjchem.6b00381