Contribution of the cold shock protein CspA to virulence in Xanthomonas oryzae pv. oryzae

Abstract

Summary Xanthomonas oryzae pv. oryzae ( Xoo ) causes a damaging bacterial leaf blight disease in rice. Cold shock proteins (Csps) are highly conserved nucleic acid‐binding proteins present in various bacterial genera, but relatively little is known about their functions in Xanthomonas . Herein, we identified four Csps (CspA–CspD) in the Xoo PXO99 A strain. Deletion of cspA decreased cold adaptation and a few known pathogenic factors, including bacterial pathogenicity, biofilm formation and polysaccharide production. Furthermore, we performed transcriptomic and chromosome immunoprecipitation (ChIP) experiments to identify direct targets of CspA and to determine its DNA‐binding sequence. Integrative data analysis revealed that CspA directly regulates two genes, PXO_RS11830 and PXO_RS01060 , by binding to a conserved CCAAT sequence in the promoter region. We generated single‐deletion mutants of each gene and the results indicate that both are responsible for Xanthomonas pathogenicity. In addition, quantitative real‐time polymerase chain reaction and western blotting showed that CspA suppressed the expression of its direct targets. In summary, our study clarifies the characteristics of Csps in Xanthomonas and greatly advances our understanding of the mechanisms underlying the contribution of CspA to bacterial virulence.

Csp1, A Cold-Shock Protein Homolog in Xylella fastidiosa Influences Pili Formation, Stress Response, and Gene Expression

“…Bacterial Csp homologs are involved in a wide range of functions including cold tolerance, general stress response, and virulence (12,17,23). Csps involved in both stress response and virulence have been found in many animal pathogens such as L. monocytogenes (16,19), Brucella melitensis (24), Salmonella enterica serovar Typhimurium (14), Enterococcus fecalis (23), Staphylococcus aureus (25), as well as plant pathogens Xanthomonas oryzae pv.…”

“…Csps involved in both stress response and virulence have been found in many animal pathogens such as L. monocytogenes (16,19), Brucella melitensis (24), Salmonella enterica serovar Typhimurium (14), Enterococcus fecalis (23), Staphylococcus aureus (25), as well as plant pathogens Xanthomonas oryzae pv. oryzae (17) and X. fastidiosa (12). Deleting Csp genes in these bacteria resulted in attenuated virulence, sometimes together with changes to cellular aggregation, surface attachment, and biofilm formation (19).…”

“…The Xanthomonas oryzae pv. oryzae (Xoo) CspA protein regulates expression of two virulence genes, PXO_RS11830 and PXO_RS01060 (17). Deletion of Xoo cspA decreased cold tolerance, bacterial pathogenicity, biofilm formation and polysaccharide production (17).…”

“…One notable difference is the X. fastidiosa genome encodes only two known cold shock protein (Csp) homologs, Csp1 and Csp2 (12), while other bacteria like E. coli and Salmonella enterica have upwards of nine (13)(14)(15). Most research on bacterial cold shock proteins have focused on their role in helping bacteria adapt and survive at suboptimal temperatures, however several studies show some Csps also contribute to virulence and general stress response (14,(16)(17)(18). In E. coli, five of the nine Csps (CspA, CspB, CspE, CspG and CspI) are induced by changes in temperature (15), while CspC and CspE are constitutively expressed at normal growth temperatures (37°C) and are involved in regulating stress response gene expression (13)…”

Proteomics of the Honeydew from the Brown Planthopper and Green Rice Leafhopper Reveal They Are Rich in Proteins from Insects, Rice Plant and Bacteria

“…CSP was identified from bacteria as a PAMP in tobacco [ 73 ]. CSP was identified from Xoo as important for virulence against rice [ 81 ]. In the present study, two CSP proteins from Escherichia and Buchnera were identified in both BPH and GRH honeydews.…”