
A. baumannii の細胞表層多糖は、自身の VI 型分泌システムの活性を抑制することで、細菌間競争において防御的な役割を果たす。


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The type VI secretion system (T6SS) is a sophisticated, contact-dependent nanomachine involved in interbacterial competition. To function effectively, the T6SS must penetrate the membranes of both attacker and target bacteria. Structures associated with the cell envelope, like polysaccharides chains, can therefore introduce spatial separation and steric hindrance, potentially affecting the efficacy of the T6SS. In this study, we examined how the capsular polysaccharide (CPS) of Acinetobacter baumannii affects T6SS’s antibacterial function. Our findings show that the CPS confers resistance against T6SS-mediated assaults from rival bacteria. Notably, under typical growth conditions, the presence of the surface-bound capsule also reduces the efficacy of the bacterium’s own T6SS. This T6SS impairment is further enhanced when CPS is overproduced due to genetic modifications or antibiotic treatment. Furthermore, we demonstrate that the bacterium adjusts the level of the T6SS inner tube protein Hcp according to its secretion capacity, by initiating a degradation process involving the ClpXP protease. Collectively, our findings contribute to a better understanding of the dynamic relationship between T6SS and CPS and how they respond swiftly to environmental challenges.

### Competing Interest Statement

The authors have declared no competing interest.

Capsular Polysaccharide Restrains Type VI Secretion in Acinetobacter baumannii

a-baumannii-の細胞表層多糖が-vi-型分泌システムの活性を抑制する


A. baumannii の細胞表層多糖が VI 型分泌システムの活性を抑制する
