Fortwendel Jarrod R, Zhao Wei, Bhabhra Ruchi, Park Steven, Perlin David S, Askew David S, Rhodes Judith C
Department of Pathology and Laboratory Medicine, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267-0529, USA.
Eukaryot Cell. 2005 Dec;4(12):1982-9. doi: 10.1128/EC.4.12.1982-1989.2005.
The Ras family of GTPase proteins has been shown to control morphogenesis in many organisms, including several species of pathogenic fungi. In a previous study, we identified a gene encoding a fungus-specific Ras subfamily homolog, rasB, in Aspergillus fumigatus. Here we report that deletion of A. fumigatus rasB caused decreased germination and growth rates on solid media but had no effect on total biomass accumulation after 24 h of growth in liquid culture. The DeltarasB mutant had an irregular hyphal morphology characterized by increased branching. Expression of rasBDelta113-135, a mutant transgene lacking the conserved rasB internal amino acid insertion, did not complement the deletion phenotype of delayed growth and germination rates and abnormal hyphal morphology. Virulence of the rasB deletion strain was diminished; mice infected with this strain exhibited approximately 65% survival compared to approximately 10% with wild-type and reconstituted strains. These data support the hypothesis that rasB homologs, which are highly conserved among fungi that undergo hyphal growth, control signaling modules important to the directional growth of fungal hyphae.
GTP酶蛋白的Ras家族已被证明可控制许多生物体的形态发生，包括几种致病真菌。在先前的一项研究中，我们在烟曲霉中鉴定出一个编码真菌特异性Ras亚家族同源物rasB的基因。在此我们报告，烟曲霉rasB的缺失导致在固体培养基上的萌发和生长速率降低，但在液体培养24小时后对总生物量积累没有影响。ΔrasB突变体具有不规则的菌丝形态，其特征是分支增加。rasBDelta113 - 135是一种缺乏保守的rasB内部氨基酸插入的突变转基因，其表达不能补充生长和萌发速率延迟以及菌丝形态异常的缺失表型。rasB缺失菌株的毒力减弱；与野生型和重组菌株感染后约10%的存活率相比，感染该菌株的小鼠存活率约为65%。这些数据支持这样的假设，即在进行菌丝生长的真菌中高度保守的rasB同源物控制着对真菌菌丝定向生长重要的信号模块。
