Deletion of the gliP gene of Aspergillus fumigatus results in loss of gliotoxin production but has no effect on virulence of the fungus in a low-dose mouse infection model
Deletion of the gliP gene of Aspergillus fumigatus results in loss of gliotoxin production but has no effect on virulence of the fungus in a low-dose mouse infection model
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DOI：
10.1111/j.1365-2958.2006.05373.x
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发表时间：
2006-10-01
影响因子：
3.6
通讯作者：
Brakhage, Axel A.
中科院分区：
文献类型：
--
作者：
Kupfahl, Claudio;Heinekamp, Thorsten;Brakhage, Axel A.
胶质毒素是几种真菌产生的次生代谢物，包括机会性人类病原体烟曲霉。由于胶质毒素在体外和体内均具有免疫抑制作用，因此在侵袭性曲霉病中作为毒力决定因素的作用已被讨论了很长时间，但迄今尚未提供证据。在这里，通过使用不同的选择标记基因，产生了烟曲霉敲除菌株，这些菌株缺乏非核糖体肽合成酶GliP，这被认为是胶质毒素生物合成的关键酶。通过高效液相色谱和串联质谱分析，gliP基因的缺失导致胶质毒素产生的损失。野生型和glip -缺失菌株在形态和生长动力学上没有差异。在体外，glip缺陷菌株的培养上清对巨噬细胞样细胞和T细胞系的细胞毒性作用均有所降低。在侵袭性曲霉病小鼠低剂量感染模型中，小鼠肺部检测到胶质毒素，而gliP缺失菌株感染小鼠时则不存在胶质毒素。然而，gliP缺失菌株与相应的野生型菌株相比，毒力没有差异。综上所述，非核糖体肽合成酶GliP对烟曲霉的胶质毒素产生至关重要。尽管gliP缺失菌株的培养上清液的细胞毒性降低，但在免疫功能低下的小鼠中，真菌的致病性不需要胶质毒素。
Gliotoxin is a secondary metabolite produced by several fungi including the opportunistic human pathogen Aspergillus fumigatus. As gliotoxin exerts immunosuppressive effects in vitro and in vivo, a role as a virulence determinant in invasive aspergillosis has been discussed for a long time but evidence has not been provided until now. Here, by the use of different selection marker genes A. fumigatus knock-out strains were generated that are deficient for the non-ribosomal peptide synthetase GliP, the putative key enzyme of the gliotoxin biosynthesis. Deletion of the gliP gene resulted in loss of gliotoxin production, as analysed by high performance liquid chromatography and tandem mass spectrometry. No differences in morphology or growth kinetics between wild-type and gliP-deletion strains were observed. In vitro, the culture supernatant of the gliP-deficient strains showed a reduced cytotoxic effect on both macrophage-like cells and T cell lines. In a low-dose murine infection model of invasive aspergillosis, gliotoxin was detected in the lung and absent when mice were infected with the gliP deletion strain. However, gliP deletion strains showed no difference in virulence compared with the corresponding wild-type strains. Taken together, the non-ribosomal peptide synthetase GliP is essential for gliotoxin production in A. fumigatus. Gliotoxin is not required for pathogenicity of the fungus in immunocompromised mice, despite the fact that a reduced cytotoxicity of the culture supernatant of gliP deletion strains was demonstrated.