Impairment of the class IIa bacteriocin receptor function and membrane structural changes are associated to enterocin CRL35 high resistance in Listeria monocytogenes

MASÍAS EMILSE; FERNANDO G. DUPUY; PAULO RICARDO DA SILVA SANCHES; JUAN V. FARIZANO; EDUARDO CILLI; AUGUSTO BELLOMIO; LUCILA SAAVEDRA; CARLOS J. MINAHK

BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2017 vol. 1861 p. 1770 - 1776

0304-4165

BACKGROUND: Enterocin CRL35 is a class IIa bacteriocin with anti-Listeria activity.Resistance to these peptides has been associated with either the downregulation of thereceptor expression or changes in the membrane and cell walls. The scope of the presentwork was to characterize enterocin CRL35 resistant Listeria strains with MICs more than10,000 times higher than the MIC of the WT sensitive strain.METHODS: Listeria monocytogenes INS7 resistant isolates R2 and R3 were characterized by16S RNA gene sequencing and rep-PCR. Bacterial growth kinetic was studied in differentculture media. Plasma membranes of sensitive and resistant bacteria were characterized byFTIR and Langmuir monolayer techniques.RESULTS: The growth kinetic of the resistant isolates was slower as compared to the parentalstrain in TSB medium. Moreover, the resistant isolates barely grew in a glucose-basedsynthetic medium, suggesting that these cells had a major alteration in glucose transport.Resistant bacteria also had alterations in their cell wall and, most importantly, membranelipids. In fact, even though enterocin CRL35 was able to bind to the membrane-water interfaceof both resistant and parental sensitive strains, this peptide was only able to get inserted intothe latter membranes.CONCLUSIONS: These results indicate that bacteriocin receptor is altered in combination withmembrane structural modifications in enterocin CRL35-resistant L. monocytogenes strains.GENERAL SIGNIFICANCE: Highly enterocin CRL35-resistant isolates derived from Listeriamonocytogenes INS7 have not only an impaired glucose transport but also display structuralchanges in the hydrophobic core of their plasma membranes.