Streptococcus suis Uptakes Carbohydrate Source from Host Glycoproteins by N-glycans Degradation System for Optimal Survival and Full Virulence during Infection.

Jiale Ma,Ze Zhang,Xiaojun Zhong,Yue Zhang,Zihao Pan,Yinchu Zhu,Huochun Yao,Guangjin Liu,Qiankun Bai,Zongfu Wu

doi:10.3390/pathogens9050387

Jiale Ma, Ze Zhang + Show 8 more

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https://doi.org/10.3390/pathogens9050387

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Journal: Pathogens	Publication Date: May 18, 2020
Citations: 4	License type: CC BY 4.0

Affiliation: Nanjing Agricultural University

Abstract

Infection with the epidemic virulent strain of Streptococcus suis serotype 2 (SS2) can cause septicemia in swine and humans, leading to pneumonia, meningitis and even cytokine storm of Streptococcal toxic shock-like syndrome. Despite some progress concerning the contribution of bacterial adhesion, biofilm, toxicity and stress response to the SS2 systemic infection, the precise mechanism underlying bacterial survival and growth within the host bloodstream remains elusive. Here, we reported the SS2 virulent strains with a more than 20 kb endoSS-related insertion region that showed significantly higher proliferative ability in swine serum than low-virulent strains. Further study identified a complete N-glycans degradation system encoded within this insertion region, and found that both GH92 and EndoSS contribute to bacterial virulence, but that only DndoSS was required for optimal growth of SS2 in host serum. The supplement of hydrolyzed high-mannose-containing glycoprotein by GH92 and EndoSS could completely restore the growth deficiency of endoSS deletion mutant in swine serum. EndoSS only hydrolyzed a part of the model glycoprotein RNase B with high-mannose N-linked glycoforms into a low molecular weight form, and the solo activity of GH92 could not show any changes comparing with the blank control in SDS-PAGE gel. However, complete hydrolyzation was observed under the co-incubation of EndoSS and GH92, suggesting GH92 may degrade the high-mannose arms of N-glycans to generate a substrate for EndoSS. In summary, these findings provide compelling evidences that EndoSS-related N-glycans degradation system may enable SS2 to adapt to host serum-specific availability of carbon sources from glycoforms, and be required for optimal colonization and full virulence during systemic infection.

Highlights

Streptococcus suis is considered to be one of the important bacterial pathogens in the swine industry and represents a significant threat to human health [1,2,3]
ZY05719 in swine serum in vitro or bloodstream in vivo during systemic infection relies on the EndoSS-related N-glycans degradation system
EndoSS and GH92 were identified to play important roles in N-glycans degradation of model glycoproteins RNase B and fetuin, which contribute to the uptake of the carbohydrate source to support bacterial growth, they may facilitate

Summary

Introduction

Streptococcus suis is considered to be one of the important bacterial pathogens in the swine industry and represents a significant threat to human health [1,2,3]. Host serums have been used to interact with bacterial pathogens for identification of important virulence factors [5,6,7], which contribute to developing new prevention and treatment strategies against bacterial infection. To survive and even proliferate in host blood, S. suis must overcome two major obstacles, the innate immunity and nutritional limit of the host [8]. The innate immunity, such as complement-mediated opsonophagocytosis and antimicrobial peptide-mediated killing, is the first barrier of host blood that S. suis need to overcome to establish sustained bacteremia. To adapt the metal-ions limited condition, numerous metal-ions acquisition systems including feoB, SSU0308 and troA have been reported in S. suis to uptake metal-ions from host blood during systematic infection [11,12,13]

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