Liebmann Burghard, Mühleisen Thomas W, Müller Meike, Hecht Matthias, Weidner Gerhard, Braun Armin, Brock Matthias, Brakhage Axel A
Institut für Mikrobiologie, Universität Hannover, Schneiderberg 50, 30167, Hannover, Germany.
Arch Microbiol. 2004 May;181(5):378-83. doi: 10.1007/s00203-004-0667-3. Epub 2004 Mar 30.
Aspergillus fumigatus is an important pathogen of the immunocompromised host, causing pneumonia and invasive disseminated disease with high mortality. In order to determine the importance of lysine biosynthesis for growth and pathogenicity, the A. fumigatus lysF gene, encoding a homologue of the A. nidulans homoaconitase LysF, was cloned and characterized. Cosmid cosGTM encoding lysF complemented a lysF mutant of Aspergillus nidulans. A. fumigatus lysF was deleted, resulting in a lysine-auxotroph. This phenotype was complemented to the wild-type by supplementation of the medium with both L-lysine and alpha-aminoadipic acid, or transformation using cosmid cosGTM. To study the virulence of the lysF deletion mutant of A. fumigatus, a low-dose intranasal mouse infection model of invasive aspergillosis was optimized for immunosuppressed BALB/c mice, allowing the application of an infection dose as low as 5 x 10(3) conidia per mouse. In this murine model, the Delta lysF mutant was avirulent, suggesting that lysine biosynthesis, or at least a functional homoaconitase, is important for survival of A. fumigatus in vivo and a potential target for antifungal drugs.
烟曲霉是免疫功能低下宿主的重要病原体，可引发肺炎和侵袭性播散性疾病，死亡率很高。为了确定赖氨酸生物合成对生长和致病性的重要性，克隆并鉴定了编码构巢曲霉高乌头酸酶LysF同源物的烟曲霉lysF基因。编码lysF的黏粒cosGTM可互补构巢曲霉的lysF突变体。敲除了烟曲霉的lysF，导致其成为赖氨酸营养缺陷型。通过在培养基中添加L-赖氨酸和α-氨基己二酸，或使用黏粒cosGTM进行转化，可将该表型恢复为野生型。为了研究烟曲霉lysF缺失突变体的毒力，针对免疫抑制的BALB/c小鼠优化了侵袭性曲霉病的低剂量鼻内小鼠感染模型，使得每只小鼠的感染剂量可低至5×10³分生孢子。在该小鼠模型中，ΔlysF突变体无毒，这表明赖氨酸生物合成，或至少一种功能性的高乌头酸酶，对烟曲霉在体内的存活很重要，并且是抗真菌药物的潜在靶点。
