title: Effects of the antimicrobial peptide gomesin on the global gene expression profile, virulence and biofilm formation of Xylella fastidiosa.
abstract: In the xylem vessels of susceptible hosts, such as citrus trees, Xylella fastidiosa forms biofilm-like colonies that can block water transport, which appears to correlate to disease symptoms. Besides aiding host colonization, bacterial biofilms play an important role in resistance against antimicrobial agents, for instance antimicrobial peptides (AMPs). Here, we show that gomesin, a potent AMP from a tarantula spider, modulates X. fastidiosa gene expression profile upon 60 min of treatment with a sublethal concentration. DNA microarray hybridizations revealed that among the upregulated coding sequences, some are related to biofilm production. In addition, we show that the biofilm formed by gomesin-treated bacteria is thicker than that formed by nontreated cells or cells exposed to streptomycin. We have also observed that the treatment of X. fastidiosa with a sublethal concentration of gomesin before inoculation in tobacco plants correlates with a reduction in foliar symptoms, an effect possibly due to the trapping of bacterial cells to fewer xylem vessels, given the enhancement in biofilm production. These results warrant further investigation of how X. fastidiosa would respond to the AMPs produced by citrus endophytes and by the insect vector, leading to a better understanding of the mechanism of action of these molecules on bacterial virulence.
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, SP, Brazil.
authors.forename: Andréa C
authors.initials: AC
authors.lastname: Fogaça
authors.forename: Paulo A
authors.initials: PA
authors.lastname: Zaini
authors.forename: Nelson A
authors.initials: NA
authors.lastname: Wulff
authors.forename: Patrícia I P
authors.initials: PI
authors.lastname: da Silva
authors.forename: Marcos A
authors.initials: MA
authors.lastname: Fázio
authors.forename: Antônio
authors.initials: A
authors.lastname: Miranda
authors.forename: Sirlei
authors.initials: S
authors.lastname: Daffre
authors.forename: Aline M
authors.initials: AM
authors.lastname: da Silva
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D020411:Oligonucleotide Array Sequence Analysis; D010935:Plant Diseases / Q000382:microbiology; D014026:Nicotiana / Q000382:microbiology; D014774:Virulence / Q000187:drug effects; D044167:Xylella / Q000187:drug effects* / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; C415987:gomesin