Cationic bactericidal peptide 1018 does not specifically target the stringent response alarmone (p)ppGpp.
The bacterial stringent response is a key regulator of bacterial virulence, biofilm formation and antibiotic tolerance, and is a promising target for the development of new antibacterial compounds. The intracellular nucleotide (p)ppGpp acts as a messenger orchestrating the stringent response. A synthetic peptide 1018 was recently proposed to specifically disrupt biofilms by inhibiting the stringent response via direct interaction with (p)ppGpp (de la Fuente-Núñez et al. (2014) PLoS Pathogens). We have interrogated the specificity of the proposed molecular mechanism. When inhibition of Pseudomonas aeruginosa planktonic and biofilm growth is tested simultaneously in the same assay, peptides 1018 and the control peptide 8101 generated by an inversion of the amino acid sequence of 1018 are equally potent, and, importantly, do not display a preferential activity against biofilm. 1018 inhibits planktonic growth of Escherichia coli equally efficiently either when the alleged target, (p)ppGpp, is essential (MOPS media lacking amino acid L-valine), or dispensable for growth (MOPS media supplemented with L-valine). Genetic disruption of the genes relA and spoT responsible for (p)ppGpp synthesis moderately sensitizes - rather than protects - E. coli to 1018. We suggest that the antimicrobial activity of 1018 does not rely on specific recognition of the stringent response messenger (p)ppGpp.
Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, SE-901 87 Umeå, Sweden.|Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Building 6K and 6L, University Hospital Area, SE-901 87 Umeå, Sweden.
Liis
L
Andresen
University of Tartu, Institute of Technology, Nooruse 1, 50411 Tartu, Estonia.
Tanel
T
Tenson
Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, SE-901 87 Umeå, Sweden.|Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Building 6K and 6L, University Hospital Area, SE-901 87 Umeå, Sweden.|University of Tartu, Institute of Technology, Nooruse 1, 50411 Tartu, Estonia.
Vasili
V
Hauryliuk
D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism*; D018441:Biofilms / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism; D006158:Guanosine Pentaphosphate / Q000378:metabolism*; D006159:Guanosine Tetraphosphate / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000378:metabolism; D014633:Valine / Q000378:metabolism
D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D010455:Peptides; D006159:Guanosine Tetraphosphate; D006158:Guanosine Pentaphosphate; D014633:Valine