title: Antimicrobial nodule-specific cysteine-rich peptides induce membrane depolarization-associated changes in the transcriptome of Sinorhizobium meliloti.
abstract: Leguminous plants establish symbiosis with nitrogen-fixing alpha- and betaproteobacteria, collectively called rhizobia, which provide combined nitrogen to support plant growth. Members of the inverted repeat-lacking clade of legumes impose terminal differentiation on their endosymbiotic bacterium partners with the help of the nodule-specific cysteine-rich (NCR) peptide family composed of close to 600 members. Among the few tested NCR peptides, cationic ones had antirhizobial activity measured by reduction or elimination of the CFU and uptake of the membrane-impermeable dye propidium iodide. Here, the antimicrobial spectrum of two of these peptides, NCR247 and NCR335, was investigated, and their effect on the transcriptome of the natural target Sinorhizobium meliloti was characterized. Both peptides were able to kill quickly a wide range of Gram-negative and Gram-positive bacteria; however, their spectra were only partially overlapping, and differences were found also in their efficacy on given strains, indicating that the actions of NCR247 and NCR335 might be similar though not identical. Treatment of S. meliloti cultures with either peptide resulted in a quick downregulation of genes involved in basic cellular functions, such as transcription-translation and energy production, as well as upregulation of genes involved in stress and oxidative stress responses and membrane transport. Similar changes provoked mainly in Gram-positive bacteria by antimicrobial agents were coupled with the destruction of membrane potential, indicating that it might also be a common step in the bactericidal actions of NCR247 and NCR335.
authors.affiliation: Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary.
authors.forename: Hilda
authors.initials: H
authors.lastname: Tiricz
authors.forename: Attila
authors.initials: A
authors.lastname: Szucs
authors.forename: Attila
authors.initials: A
authors.lastname: Farkas
authors.forename: Bernadett
authors.initials: B
authors.lastname: Pap
authors.forename: Rui M
authors.initials: RM
authors.lastname: Lima
authors.forename: Gergely
authors.initials: G
authors.lastname: Maróti
authors.forename: Éva
authors.initials: É
authors.lastname: Kondorosi
authors.forename: Attila
authors.initials: A
authors.lastname: Kereszt
mesh_terms: D000595:Amino Acid Sequence; D023181:Antimicrobial Cationic Peptides / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism*; D019295:Computational Biology; D003545:Cysteine / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects* / Q000235:genetics; D008969:Molecular Sequence Data; D011419:Propidium; D017423:Sequence Analysis, RNA; D016962:Sinorhizobium meliloti / Q000235:genetics / Q000378:metabolism*; D059467:Transcriptome / Q000235:genetics*
chemical_list: D023181:Antimicrobial Cationic Peptides; D011419:Propidium; D003545:Cysteine