Stöckli Martina, Lin Chia-Wei, Sieber Ramon, Plaza David F, Ohm Robin A, Künzler Markus
Institute of Microbiology, Department of Biology, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland.
Microbiology, Faculty of Science, Utrecht University, Padualaan 8, 3584 Utrecht, The Netherlands.
Fungal Genet Biol. 2017 May;102:49-62. doi: 10.1016/j.fgb.2016.07.009. Epub 2016 Jul 27.
Biofilm formation on fungal hyphae and production of antifungal molecules are strategies of bacteria in their competition with fungi for nutrients. Since these strategies are often coordinated and under control of quorum sensing by the bacteria, interference with this bacterial communication system can be used as a counter-strategy by the fungi in this competition. Hydrolysis of N-acyl-homoserine lactones (HSL), a quorum sensing molecule used by Gram-negative bacteria, by fungal cultures has been demonstrated. However, the enzymes that are responsible for this activity, have not been identified. In this study, we identified and characterized two paralogous HSL hydrolyzing enzymes from the coprophilous fungus Coprinopsis cinerea. The C. cinerea HSL lactonases belong to the metallo-β-lactamase family and show sequence homology to and a similar biochemical activity as the well characterized lactonase AiiA from Bacillus thuringiensis. We show that the fungal lactonases, similar to the bacterial enzymes, are kept intracellularly and act as a sink for the bacterial quorum sensing signals both in C. cinerea and in Saccharomyces cerevisiae expressing C. cinerea lactonases, due to the ability of these signal molecules to diffuse over the fungal cell wall and plasma membrane. The two isogenes coding for the C. cinerea HSL lactonases are arranged in the genome as a tandem repeat and expressed preferentially in vegetative mycelium. The occurrence of orthologous genes in genomes of other basidiomycetes appears to correlate with a saprotrophic lifestyle.
细菌在与真菌争夺营养的过程中，在真菌菌丝上形成生物膜以及产生抗真菌分子是其采用的策略。由于这些策略通常相互协调且受细菌群体感应的控制，真菌在这场竞争中可以通过干扰这种细菌通讯系统作为应对策略。已经证明，真菌培养物能够水解革兰氏阴性菌所使用的群体感应分子N-酰基高丝氨酸内酯（HSL）。然而，负责这种活性的酶尚未被鉴定出来。在本研究中，我们从粪生真菌灰盖鬼伞中鉴定并表征了两种同源的HSL水解酶。灰盖鬼伞HSL内酯酶属于金属β-内酰胺酶家族，与来自苏云金芽孢杆菌的已得到充分表征的内酯酶AiiA具有序列同源性和相似的生化活性。我们发现，与细菌酶类似，真菌内酯酶保留在细胞内，并且在灰盖鬼伞以及表达灰盖鬼伞内酯酶的酿酒酵母中，由于这些信号分子能够扩散穿过真菌细胞壁和质膜，它们充当了细菌群体感应信号的汇聚点。编码灰盖鬼伞HSL内酯酶的两个同基因在基因组中以串联重复的形式排列，并且在营养菌丝体中优先表达。其他担子菌基因组中直系同源基因的出现似乎与腐生生活方式相关。
