Identification of Proteus mirabilis Mutants with Increased Sensitivity to Antimicrobial Peptides

AUTOR(ES)

McCoy, Andrea J.

FONTE

American Society for Microbiology

RESUMO

Antimicrobial peptides (APs) are important components of the innate defenses of animals, plants, and microorganisms. However, some bacterial pathogens are resistant to the action of APs. For example, Proteus mirabilis is highly resistant to the action of APs, such as polymyxin B (PM), protegrin, and the synthetic protegrin analog IB-367. To better understand this resistance, a transposon mutagenesis approach was used to generate P. mirabilis mutants sensitive to APs. Four unique PM-sensitive mutants of P. mirabilis were identified (these mutants were >2 to >128 times more sensitive than the wild type). Two of these mutants were also sensitive to IB-367 (16 and 128 times more sensitive than the wild type). Lipopolysaccharide (LPS) profiles of the PM- and protegrin-sensitive mutants demonstrated marked differences in both the lipid A and O-antigen regions, while the PM-sensitive mutants appeared to have alterations of either lipid A or O antigen. Matrix-assisted laser desorption ionization–time of flight mass spectrometry analysis of the wild-type and PM-sensitive mutant lipid A showed species with one or two aminoarabinose groups, while lipid A from the PM- and protegrin-sensitive mutants was devoid of aminoarabinose. When the mutants were streaked on an agar-containing medium, the swarming motility of the PM- and protegrin-sensitive mutants was completely inhibited and the swarming motility of the mutants sensitive to only PM was markedly decreased. DNA sequence analysis of the mutagenized loci revealed similarities to an O-acetyltransferase (PM and protegrin sensitive) and ATP synthase and sap loci (PM sensitive). These data further support the role of LPS modifications as an elaborate mechanism in the resistance of certain bacterial species to APs and suggest that LPS surface charge alterations may play a role in P. mirabilis swarming motility.

Documentos Relacionados

• Proteus mirabilis ZapA Metalloprotease Degrades a Broad Spectrum of Substrates, Including Antimicrobial Peptides
• Arabidopsis mutants with increased sensitivity to aluminum.
• Diversity of TEM Mutants in Proteus mirabilis
• Mutants of Staphylococcus aureus with Increased Sensitivity to Ultraviolet Radiation
• Characterization of Proteus mirabilis Precocious Swarming Mutants: Identification of rsbA, Encoding a Regulator of Swarming Behavior