Riemerella anatipestifer Type IX Secretion System Is Required for Virulence and Gelatinase Secretion

Guo, Yunqing; Hu, Di; Guo, Jie; Wang, Tao; Xiao, Yufei; Wang, Xiliang; Li, Shaowen; Liu, Mei; Li, Zili; Bi, Dingren; Zhou, Zutao

doi:10.3389/fmicb.2017.02553

Cited by 32 publications

(21 citation statements)

References 48 publications

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“…The importance of T9SSs in the nutrition, physiology, motility, and virulence of members of the phylum Bacteroidetes has been demonstrated (1,3,19,36,(38)(39)(40). Most of the proteins with easily predicted functions that are secreted by T9SSs have type A CTDs.…”

Section: Discussionmentioning

confidence: 99%

The Carboxy-Terminal Region of Flavobacterium johnsoniae SprB Facilitates Its Secretion by the Type IX Secretion System and Propulsion by the Gliding Motility Machinery

et al. 2019

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Flavobacterium johnsoniae SprB moves rapidly along the cell surface, resulting in gliding motility. SprB secretion requires the type IX secretion system (T9SS). Proteins secreted by the T9SS typically have conserved C-terminal domains (CTDs) belonging to the type A CTD or type B CTD family. Attachment of 70- to 100-amino-acid type A CTDs to a foreign protein allows its secretion. Type B CTDs are common but have received little attention. Secretion of the foreign protein superfolder green fluorescent protein (sfGFP) fused to regions spanning the SprB type B CTD (sfGFP-CTDSprB) was analyzed. CTDs of 218 amino acids or longer resulted in secretion of sfGFP, whereas a 149-amino-acid region did not. Some sfGFP was secreted in soluble form, whereas the rest was attached on the cell surface. Surface-attached sfGFP was rapidly propelled along the cell, suggesting productive interaction with the motility machinery. This did not result in rapid cell movement, which apparently requires additional regions of SprB. Secretion of sfGFP-CTDSprB required coexpression with sprF, which lies downstream of sprB. SprF is similar in sequence to Porphyromonas gingivalis PorP. Most F. johnsoniae genes encoding proteins with type B CTDs lie immediately upstream of porP/sprF-like genes. sfGFP was fused to the type B CTD from one such protein (Fjoh_3952). This resulted in secretion of sfGFP only when it was coexpressed with its cognate PorP/SprF-like protein. These results highlight the need for extended regions of type B CTDs and for coexpression with the appropriate PorP/SprF-like protein for efficient secretion and cell surface localization of cargo proteins. IMPORTANCE The F. johnsoniae gliding motility adhesin SprB is delivered to the cell surface by the type IX secretion system (T9SS) and is rapidly propelled along the cell by the motility machinery. How this 6,497-amino-acid protein interacts with the secretion and motility machines is not known. Fusion of the C-terminal 218 amino acids of SprB to a foreign cargo protein resulted in its secretion, attachment to the cell surface, and rapid movement by the motility machinery. Efficient secretion of SprB required coexpression with the outer membrane protein SprF. Secreted proteins that have sequence similarity to SprB in their C-terminal regions are common in the phylum Bacteroidetes and may have roles in adhesion, motility, and virulence.

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Section: Discussionmentioning

confidence: 99%

The Carboxy-Terminal Region of Flavobacterium johnsoniae SprB Facilitates Its Secretion by the Type IX Secretion System and Propulsion by the Gliding Motility Machinery

et al. 2019

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“…Duck serositis, caused by Riemerella anatipestifer , is an important communicable disease (Zheng et al, 2012; Guo et al, 2017). R. anatipestifer is a gram-negative, rod-shaped, non-spore-forming, non-motile bacterium that can primarily infect ducks that are l−5 weeks of age, via the respiratory or digestive tracts (Chikuba et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Interplay Between the Phenotype and Genotype, and Efflux Pumps in Drug-Resistant Strains of Riemerella anatipestifer

et al. 2018

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The number of multidrug-resistant strains of Riemerella anatipestifer continues to increase, and new strategies for the treatment of associated infections are necessary. Recently, numerous studies have shown that efflux pumps (EPs) play key roles in universal bacterial mechanisms that contribute to antibiotic resistance. In addition, studies have shown that the effects of antibiotics that are subjected to efflux can be reinforced by their combined use with efflux pump inhibitors (EPIs). Unfortunately, the role of the efflux system in R. anatipestifer remains barely understood. In this study, we evaluated the role of EPs and resistance genes in the resistance generated by clinical strains of R. anatipestifer to antibiotics. A set of 10 R. anatipestifer strains were characterized by drug resistance, associated resistance genes, and antibiotic profiles in the presence and absence of EPIs. Efflux activity was studied on a real time basis through a fluorometric method. Quantification of the levels of mRNA transcription of efflux pump genes (EPGs) was determined by RT-qPCR. Several approaches (detection of resistance genes, drug susceptibility testing, and growth kinetics analysis) were used to assess the correlation between the effect of the EPIs and the resistance levels. Analysis of the R. anatipestifer growth inhibition tests showed that the antibiotic activity was enhanced by the synergy of EPIs. Among the various resistance genes that confer antibiotic resistance, different minimum inhibitory concentrations (MICs) were observed. The different levels of resistance were reduced by EPIs. Real time fluorometry showed that all the R. anatipestifer strains presented inherent efflux activity, conferring varying levels of inhibition in the presence of EPIs. Moreover, 15 EPGs were overexpressed in the presence of antibiotics. The addition of EPIs to antibiotics led to downregulation in the expression of some EPGs and a simultaneous increase in drug resistance and sensitivity. These results demonstrated the contribution of these EPs in the resistant phenotype of the clinical strains of R. anatipestifer that are under investigation, independently of the resistant genotype of the respective strains. Intrinsic efflux activity was possibly linked to the evolution of resistance in multidrug-resistant isolates of R. anatipestifer. Furthermore, the inhibition of EPs by EPIs could enhance the clinical effects of antibiotics.

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“…The sprT gene encodes the T9SS component SprT, which is involved in the protein secretion and virulence of R . anatipestifer [21]. However, the functions of other T9SS components in R .…”

Section: Discussionmentioning

confidence: 99%

“…SprT, encoded by the sprT gene, is a T9SS protein involved in protein secretion in R. anatipestifer . T9SS is functional in R. anatipestifer and contributes to its virulence by exporting key proteins [21]. The T9SS component GldM is required for bacterial gliding motility and the secretion of the cell-surface motility adhesins SprB and RemA in F. johnsoniae [22].…”

Section: Introductionmentioning

confidence: 99%

Riemerella anatipestifer GldM is required for bacterial gliding motility, protein secretion, and virulence

Chen

Wang

Ren

et al. 2019

Vet Res

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Riemerella anatipestifer is a major pathogenic agent of duck septicemic and exudative diseases. Genetic analyses suggest that this pathogen has a novel protein secretion system, known as the “type IX secretion system” (T9SS). We previously reported that deletion of the AS87_RS08465 gene significantly reduced the bacterial virulence of the R. anatipestifer strain Yb2, but the mechanism remained unclear. The AS87_RS08465 gene is predicted to encode the gliding motility protein GldM (GldM) protein, a key component of the T9SS complex. In this study, Western blotting analysis demonstrated that R. anatipestifer GldM was localized to the cytomembrane. Further study revealed that the adhesion and invasion capacities of the mutant strain RA2281 (designated Yb2Δ gldM ) in Vero cells and the bacterial loads in the blood of infected ducks were significantly reduced. RNA-Seq and PCR analyses showed that six genes were upregulated and five genes were downregulated in the mutant strain Yb2Δ gldM and that these genes were mainly involved in the secretion of proteins. Yb2Δ gldM was also found to be defective in gliding motility and protein secretion. Liquid chromatography–tandem mass spectrometry analysis revealed that nine of the proteins had a conserved T9SS C-terminal domain and were differentially secreted by Yb2Δ gldM compared to Yb2. The complementation strain cYb2Δ gldM recovered the adhesion and invasion capacities in Vero cells and the bacterial loads in the blood of infected ducks as well as the bacterial gliding motility and most protein secretion in the mutant strain Yb2Δ gldM to the levels of the wild-type strain Yb2. Taken together, these results indicate that R. anatipestifer GldM is associated with T9SS and is important in bacterial virulence. Electronic supplementary material The online version of this article (10.1186/s13567-019-0660-0) contains supplementary material, which is available to authorized users.

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Riemerella anatipestifer Type IX Secretion System Is Required for Virulence and Gelatinase Secretion

Cited by 32 publications

References 48 publications

The Carboxy-Terminal Region of Flavobacterium johnsoniae SprB Facilitates Its Secretion by the Type IX Secretion System and Propulsion by the Gliding Motility Machinery

The Carboxy-Terminal Region of Flavobacterium johnsoniae SprB Facilitates Its Secretion by the Type IX Secretion System and Propulsion by the Gliding Motility Machinery

Interplay Between the Phenotype and Genotype, and Efflux Pumps in Drug-Resistant Strains of Riemerella anatipestifer

Riemerella anatipestifer GldM is required for bacterial gliding motility, protein secretion, and virulence

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