CdrA Interactions within the Pseudomonas aeruginosa Biofilm Matrix Safeguard It from Proteolysis and Promote Cellular Packing.
CdrA Interactions within the Pseudomonas aeruginosa Biofilm Matrix Safeguard It from Proteolysis and Promote Cellular Packing.
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DOI：
10.1128/mbio.01376-18
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发表时间：
2018-09-25
期刊：
影响因子：
6.4
通讯作者：
Parsek MR
中科院分区：
文献类型：
--
作者：
Reichhardt C;Wong C;Passos da Silva D;Wozniak DJ;Parsek MR
铜绿假单胞菌使用胞外多糖和CdrA基质粘附素形成多细胞聚集体或生物膜。我们首次证明铜绿假单胞菌可以使用CdrA来构建不需要已知基质胞外多糖的生物膜。应当理解，生物膜生长是针对环境攻击的保护。然而，很少有人知道如何在这种保护个别矩阵组件之间的相互作用。我们发现CdrA和胞外多糖Psl之间的相互作用通过防止CdrA蛋白水解来强化基质。当两种组分-CdrA和Psl-都是基质的一部分时，形成紧密堆积且具有蛋白酶抗性的坚固聚集体。这些发现提供了深入了解生物膜如何在富含蛋白酶的宿主环境中持续存在。生物膜是包裹在细胞外基质中的强大的多细胞细菌聚集体。不同的细菌物种已被证明使用一系列生物聚合物来构建它们的基质。铜绿假单胞菌是实验室研究生物膜的模式生物，过去的工作表明胞外多糖是所需的基质组分。然而，我们发现，在没有生物膜胞外多糖的情况下，基质蛋白CdrA的表达允许通过产生富含CdrA的蛋白质基质形成生物膜。这代表了CdrA的新功能。对其他物种如大肠杆菌和金黄色葡萄球菌也进行了类似的观察，它们可以利用蛋白质占主导地位的生物膜基质。然而，我们发现，这些含CdrA的基质对外源性和自身产生的蛋白酶都敏感。我们先前报道了CdrA直接结合生物膜基质胞外多糖Psl。现在我们已经发现，当CdrA与Psl结合时，它被保护免于蛋白水解。总之，这些结果支持了多生物分子组分在基质稳定性中的重要性的想法，并使我们提出了一种模型，其中CdrA-CdrA相互作用可以增强聚集体中的细胞-细胞包装，该聚集体对物理剪切具有抗性，而Psl-CdrA相互作用在自产和外源蛋白酶的存在下增强聚集体的完整性。
Pseudomonas aeruginosa forms multicellular aggregates or biofilms using both exopolysaccharides and the CdrA matrix adhesin. We showed for the first time that P. aeruginosa can use CdrA to build biofilms that do not require known matrix exopolysaccharides. It is appreciated that biofilm growth is protective against environmental assaults. However, little is known about how the interactions between individual matrix components aid in this protection. We found that interactions between CdrA and the exopolysaccharide Psl fortify the matrix by preventing CdrA proteolysis. When both components—CdrA and Psl—are part of the matrix, robust aggregates form that are tightly packed and protease resistant. These findings provide insight into how biofilms persist in protease-rich host environments. Biofilms are robust multicellular aggregates of bacteria that are encased in an extracellular matrix. Different bacterial species have been shown to use a range of biopolymers to build their matrices. Pseudomonas aeruginosa is a model organism for the laboratory study of biofilms, and past work has suggested that exopolysaccharides are a required matrix component. However, we found that expression of the matrix protein CdrA, in the absence of biofilm exopolysaccharides, allowed biofilm formation through the production of a CdrA-rich proteinaceous matrix. This represents a novel function for CdrA. Similar observations have been made for other species such as Escherichia coli and Staphylococcus aureus, which can utilize protein-dominant biofilm matrices. However, we found that these CdrA-containing matrices were susceptible to both exogenous and self-produced proteases. We previously reported that CdrA directly binds the biofilm matrix exopolysaccharide Psl. Now we have found that when CdrA bound to Psl, it was protected from proteolysis. Together, these results support the idea of the importance of multibiomolecular components in matrix stability and led us to propose a model in which CdrA-CdrA interactions can enhance cell-cell packing in an aggregate that is resistant to physical shear, while Psl-CdrA interactions enhance aggregate integrity in the presence of self-produced and exogenous proteases.