Huber Florian, Bignell Elaine
Centre for Molecular Bacteriology and Infection, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.
Fungal Genet Biol. 2014 Mar;64:36-44. doi: 10.1016/j.fgb.2014.01.002. Epub 2014 Jan 15.
Functional genomic analysis of the mould pathogen Aspergillus fumigatus has identified multiple secondary metabolism genes upregulated in the host niche. Intriguingly, transcriptomic analyses of infectious germlings, germinating spores and mutants lacking the LaeA methyltransferase reveal differential expression of transposable elements (TEs), which often flank secondary metabolite gene clusters. In this study we investigate, in clinical and environmental isolates, the structure and distribution of a specific class of A. fumigatus long interspersed nuclear element (LINE)-like retrotransposons occupying subtelomeric loci in the A. fumigatus genome, and probe their stability in response to laboratory- and host-imposed stresses. In silico analyses revealed that this class belongs to the Tad clade of LINE-like elements. Southern blotting with a LINE-specific probe in clinical and environmental isolates revealed a high variability in the insertion pattern between strains and active transcription of LINE-like element(s) was discernable, in the type strain Af293, by RT-PCR. One out of 14 tested clinical isolates did not contain any LINEs at all, arguing against an absolute requirement for LINE-mediated activities in human infections. Finally, we found preliminary evidence of an association between mycovirus-infection and the expansion of Tad-element populations in discrete A. fumigatus genomes.
对霉菌病原体烟曲霉进行的功能基因组分析已鉴定出多个在宿主生态位中上调的次级代谢基因。有趣的是，对感染性芽管、萌发孢子以及缺乏LaeA甲基转移酶的突变体进行的转录组分析揭示了转座元件（TEs）的差异表达，这些转座元件通常位于次级代谢产物基因簇的侧翼。在本研究中，我们调查了临床和环境分离株中一类特定的烟曲霉长散在核元件（LINE）样逆转录转座子的结构和分布，这类元件占据了烟曲霉基因组中的亚端粒位点，并探究了它们在实验室和宿主施加的压力下的稳定性。计算机分析表明，这类元件属于LINE样元件的Tad进化枝。用LINE特异性探针在临床和环境分离株中进行Southern印迹分析，结果显示菌株间插入模式存在高度变异性，并且通过RT-PCR在模式菌株Af293中可检测到LINE样元件的活跃转录。在14个测试的临床分离株中，有1个根本不包含任何LINE，这表明在人类感染中，LINE介导的活性并非绝对必需。最后，我们发现了初步证据，表明在离散的烟曲霉基因组中，真菌病毒感染与Tad元件群体的扩增之间存在关联。
