Wza gene knockout decreases Acinetobacter baumannii virulence and affects Wzy-dependent capsular polysaccharide synthesis.

Abstract

To investigate the virulence of capsular polysaccharide export protein (Wza) in carbapenem-resistant Acinetobacter baumannii and its effect on capsule formation.wza gene knockout and complementation strains were constructed, and changes in bacterial virulence were observed using in vitro adhesion, antiserum complement killing, anti-oxidation experiments, and infections in Galleria mellonella and mice. The effect of wza knockout on the genes wzb and wzc and wzi were assessed by RT-PCR.We successfully constructed wza knockout and complementation strains. Compared with wild-type (WT) strains, wza knockout strains displayed lower adhesion to A549 cells (p = 0.044), lower antiserum complement killing ability (p = 0.001), and lower mortality of G. mellonella (p = 0.010) and mice (p = 0.033). Expression levels of wzb, wzc and wzi were decreased in wza knockout strains. The antioxidant capacity of Wza knockout bacteria was only slightly decreased. Complementation of the wza gene returned the adhesion ability, antiserum complement killing ability, and mortality of G. mellonella and mice to WT levels. Expression of wzb, wzc and wzi was also returned to WT levels following wza complementation.The results clearly demonstrate that Wza is toxic. Wza affects the expression of other proteins of the Wzy capsule polysaccharide synthesis pathway, which affects the assembly, export, and extracellular fixation of capsular polysaccharide, resulting in synergistic effects that decrease bacterial virulence.

• Authors: Tianshui Niu, Lihua Guo, Qixia Luo, Kai Zhou, Wei Yu, Yunbo Chen, Chen Huang, Yonghong Xiao
• Journal: Virulence (Virulence) Vol. 11 Issue 1 Pg. 1-13 (12 2020) ISSN: 2150-5608 [Electronic] United States
• PMID: 31878839 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Bacterial Outer Membrane Proteins
• Bacterial Proteins
• Escherichia coli Proteins
• Polysaccharides
• Wzi protein, E coli

Topics

• A549 Cells
• Acinetobacter baumannii (genetics, pathogenicity)
• Animals
• Bacterial Capsules (metabolism)
• Bacterial Outer Membrane Proteins (genetics, metabolism)
• Bacterial Proteins (genetics, metabolism)
• Disease Models, Animal
• Escherichia coli (genetics)
• Escherichia coli Proteins (genetics)
• Gene Knockout Techniques
• Humans
• Mice
• Moths
• Polysaccharides (genetics, metabolism)
• Virulence