AUTHOR=Zhao Fan , Xu Huan , Chen Yubing , Xiao Juan , Zhang Miao , Li Zhuo , Liu Jinlin , Qi Chao 

TITLE=Actinobacillus pleuropneumoniae FliY and YdjN are involved in cysteine/cystine utilization, oxidative resistance, and biofilm formation but are not determinants of virulence

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1169774

DOI=10.3389/fmicb.2023.1169774

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p><italic>Actinobacillus pleuropneumoniae</italic> (<italic>A. pleuropneumoniae</italic>) is a member of <italic>Actinobacillus</italic> in family Pasteurellaceae. It is the causative agent of porcine pleuropneumonia, which has caused huge economic losses to pig industry over the world. Cysteine is a precursor of many important biomolecules and defense compounds in the cell. However, molecular mechanisms of cysteine transport in <italic>A. pleuropneumoniae</italic> are unclear.</p></sec><sec><title>Methods</title><p>In this study, gene-deleted mutants were generated and investigated, to reveal the roles of potential cysteine/cystine transport proteins FliY and YdjN of <italic>A. pleuropneumoniae</italic>.</p></sec><sec><title>Results</title><p>Our results indicated that the growth of <italic>A. pleuropneumoniae</italic> was not affected after <italic>fliY</italic> or <italic>ydjN</italic> single gene deletion, but absence of both FliY and YdjN decreased the growth ability significantly, when cultured in the chemically defined medium (CDM) supplemented with cysteine or cystine as the only sulfur source. <italic>A. pleuropneumoniae</italic> double deletion mutant Δ<italic>fliY</italic>Δ<italic>ydjN</italic> showed increased sensitivity to oxidative stress. Besides, <italic>trans</italic>-complementation of YdjN into Δ<italic>fliY</italic>Δ<italic>ydjN</italic> and wild type leads to increased biofilm formation in CDM. However, the virulence of Δ<italic>fliY</italic>Δ<italic>ydjN</italic> was not attenuated in mice or pigs.</p></sec><sec><title>Discussion</title><p>These findings suggest that <italic>A. pleuropneumoniae</italic> FliY and YdjN are involved in the cysteine/cystine acquisition, oxidative tolerance, and biofilm formation, but not contribute to the pathogenicity of <italic>A. pleuropneumoniae</italic>.</p></sec>