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Regulation of the Gene for Alanine Racemase Modulates Amino Acid Metabolism with Consequent Alterations in Cell Wall Properties and Adhesive Capability in Brucella spp.

Authors :
Mingyue Hao
Minghui Wang
Ting Tang
Danyu Zhao
Shurong Yin
Yong Shi
Xiaofang Liu
Gaowa Wudong
Yuanhao Yang
Mengyu Zhang
Lin Qi
Dong Zhou
Wei Liu
Yaping Jin
Aihua Wang
Source :
International Journal of Molecular Sciences, Vol 24, Iss 22, p 16145 (2023)
Publication Year :
2023
Publisher :
MDPI AG, 2023.

Abstract

Brucella, a zoonotic facultative intracellular pathogenic bacterium, poses a significant threat both to human health and to the development of the livestock industry. Alanine racemase (Alr), the enzyme responsible for alanine racemization, plays a pivotal role in regulating virulence in this bacterium. Moreover, Brucella mutants with alr gene deletions (Δalr) exhibit potential as vaccine candidates. However, the mechanisms that underlie the detrimental effects of alr knockouts on Brucella pathogenicity remain elusive. Here, initially, we conducted a bioinformatics analysis of Alr, which demonstrated a high degree of conservation of the protein within Brucella spp. Subsequent metabolomics studies unveiled alterations in amino acid pathways following deletion of the alr gene. Furthermore, alr deletion in Brucella suis S2 induced decreased resistance to stress, antibiotics, and other factors. Transmission electron microscopy of simulated macrophage intracellular infection revealed damage to the cell wall in the Δalr strain, whereas propidium iodide staining and alkaline phosphatase and lactate dehydrogenase assays demonstrated alterations in cell membrane permeability. Changes in cell wall properties were revealed by measurements of cell surface hydrophobicity and zeta potential. Finally, the diminished adhesion capacity of the Δalr strain was shown by immunofluorescence and bacterial enumeration assays. In summary, our findings indicate that the alr gene that regulates amino acid metabolism in Brucella influences the properties of the cell wall, which modulates bacterial adherence capability. This study is the first demonstration that Alr impacts virulence by modulating bacterial metabolism, thereby providing novel insights into the pathogenic mechanisms of Brucella spp.

Details

Language :
English
ISSN :
14220067 and 16616596
Volume :
24
Issue :
22
Database :
Directory of Open Access Journals
Journal :
International Journal of Molecular Sciences
Publication Type :
Academic Journal
Accession number :
edsdoj.86600e9fdec4997848e3fcad99c3c3e
Document Type :
article
Full Text :
https://doi.org/10.3390/ijms242216145