Mai-Prochnow Anne, Lucas-Elio Patricia, Egan Suhelen, Thomas Torsten, Webb Jeremy S, Sanchez-Amat Antonio, Kjelleberg Staffan
School of Biotechnology and Biomolecular Sciences and Centre for Marine Bio-Innovation, Biological Sciences Building, University of New South Wales, Kensington, Sydney, NSW 2052, Australia.
J Bacteriol. 2008 Aug;190(15):5493-501. doi: 10.1128/JB.00549-08. Epub 2008 May 23.
The marine bacterium Pseudoalteromonas tunicata produces an antibacterial and autolytic protein, AlpP, which causes death of a subpopulation of cells during biofilm formation and mediates differentiation, dispersal, and phenotypic variation among dispersal cells. The AlpP homologue (LodA) in the marine bacterium Marinomonas mediterranea was recently identified as a lysine oxidase which mediates cell death through the production of hydrogen peroxide. Here we show that AlpP in P. tunicata also acts as a lysine oxidase and that the hydrogen peroxide generated is responsible for cell death within microcolonies during biofilm development in both M. mediterranea and P. tunicata. LodA-mediated biofilm cell death is shown to be linked to the generation of phenotypic variation in growth and biofilm formation among M. mediterranea biofilm dispersal cells. Moreover, AlpP homologues also occur in several other gram-negative bacteria from diverse environments. Our results show that subpopulations of cells in microcolonies also die during biofilm formation in two of these organisms, Chromobacterium violaceum and Caulobacter crescentus. In all organisms, hydrogen peroxide was implicated in biofilm cell death, because it could be detected at the same time as the killing occurred, and the addition of catalase significantly reduced biofilm killing. In C. violaceum the AlpP-homologue was clearly linked to biofilm cell death events since an isogenic mutant (CVMUR1) does not undergo biofilm cell death. We propose that biofilm killing through hydrogen peroxide can be linked to AlpP homologue activity and plays an important role in dispersal and colonization across a range of gram-negative bacteria.
海洋细菌海鞘假交替单胞菌产生一种抗菌和自溶蛋白AlpP，它在生物膜形成过程中导致一部分细胞死亡，并介导扩散细胞之间的分化、扩散和表型变异。海洋细菌地中海海单胞菌中的AlpP同源物（LodA）最近被鉴定为一种赖氨酸氧化酶，它通过产生过氧化氢介导细胞死亡。在这里，我们表明海鞘假交替单胞菌中的AlpP也作为一种赖氨酸氧化酶起作用，并且产生的过氧化氢是地中海海单胞菌和海鞘假交替单胞菌生物膜发育过程中微菌落内细胞死亡的原因。LodA介导的生物膜细胞死亡与地中海海单胞菌生物膜扩散细胞在生长和生物膜形成方面的表型变异的产生有关。此外，AlpP同源物也存在于来自不同环境的其他几种革兰氏阴性细菌中。我们的结果表明，在这两种生物——紫色杆菌和新月柄杆菌中，微菌落中的细胞亚群在生物膜形成过程中也会死亡。在所有生物中，过氧化氢与生物膜细胞死亡有关，因为在细胞死亡发生的同时可以检测到它，并且添加过氧化氢酶显著降低了生物膜细胞死亡。在紫色杆菌中，AlpP同源物与生物膜细胞死亡事件明显相关，因为一个同基因突变体（CVMUR1）不会发生生物膜细胞死亡。我们提出，通过过氧化氢进行的生物膜细胞死亡可能与AlpP同源物的活性有关，并且在一系列革兰氏阴性细菌的扩散和定殖中起重要作用。
