Burkholderia BcpA mediates biofilm formation independently of interbacterial contact-dependent growth inhibition
Burkholderia BcpA mediates biofilm formation independently of interbacterial contact-dependent growth inhibition
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DOI：
10.1111/mmi.12339
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发表时间：
2013-09-01
影响因子：
3.6
通讯作者：
Cotter, Peggy A.
中科院分区：
文献类型：
--
作者：
Garcia, Erin C.;Anderson, Melissa S.;Cotter, Peggy A.
接触依赖性生长抑制（CDI）是革兰氏阴性细菌在细胞-细胞接触时使用大的表面暴露的外蛋白的毒性C-末端来抑制敏感细菌生长的现象。关于细菌何时何地表达编码CDI系统蛋白的基因以及这些系统如何有助于细菌在其自然生态位中的生存，人们知之甚少。在这里，我们建立，除了介导细菌间的竞争，伯克霍尔德氏菌泰国CDI系统外蛋白BcpA所需的生物膜的发展。我们还提供了证据表明，BcpA和细胞外DNA的催化活性所需的特征生物膜支柱的形成。我们使用bcpA-gfp融合表明，在生物膜内，CDI系统编码基因的表达低于大多数细菌的检测限，并且只有一部分细胞在任何给定时间强烈表达基因。组成型表达基因的菌株的分析表明，天然表达是生物膜结构的关键。虽然CDI系统到目前为止只被证明是参与细菌间的竞争，在整个细菌种群的系统的免疫蛋白的组成型生产没有改变生物膜的形成，表明CDI独立的作用BcpA在这个过程中。因此，我们提出，细菌可能在合作行为中使用CDI蛋白，如建立生物膜群落，以及在竞争行为中使用CDI蛋白，以防止非自身细菌进入群落。
Contact-dependent growth inhibition (CDI) is a phenomenon in which Gram-negative bacteria use the toxic C-terminus of a large surface-exposed exoprotein to inhibit the growth of susceptible bacteria upon cell-cell contact. Little is known about when and where bacteria express the genes encoding CDI system proteins and how these systems contribute to the survival of bacteria in their natural niche. Here we establish that, in addition to mediating interbacterial competition, the Burkholderia thailandensisCDI system exoprotein BcpA is required for biofilm development. We also provide evidence that the catalytic activity of BcpA and extracellular DNA are required for the characteristic biofilm pillars to form. We show using a bcpA-gfp fusion that within the biofilm, expression of the CDI system-encoding genes is below the limit of detection for the majority of bacteria and only a subset of cells express the genes strongly at any given time. Analysis of a strain constitutively expressing the genes indicates that native expression is critical for biofilm architecture. Although CDI systems have so far only been demonstrated to be involved in interbacterial competition, constitutive production of the system's immunity protein in the entire bacterial population did not alter biofilm formation, indicating a CDI-independent role for BcpA in this process. We propose, therefore, that bacteria may use CDI proteins in cooperative behaviours, like building biofilm communities, and in competitive behaviours that prevent non-self bacteria from entering the community.