Martín-Urdíroz Magdalena, Roncero M Isabel G, González-Reyes José Antonio, Ruiz-Roldán Carmen
Departamento de Genética, Edif C5, Universidad de Córdoba, Campus Universitario de Rabanales, E-14071 Córdoba, Spain.
Eukaryot Cell. 2008 Jan;7(1):112-21. doi: 10.1128/EC.00347-07. Epub 2007 Nov 9.
A new myosin motor-like chitin synthase gene, chsVb, has been identified in the vascular wilt fungus Fusarium oxysporum f. sp. lycopersici. Phylogenetic analysis of the deduced amino acid sequence of the chsVb chitin synthase 2 domain (CS2) revealed that ChsVb belongs to class VII chitin synthases. The ChsVb myosin motor-like domain (MMD) is shorter than the MMD of class V chitin synthases and does not contain typical ATP-binding motifs. Targeted disrupted single (DeltachsVb) and double (DeltachsV DeltachsVb) mutants were unable to infect and colonize tomato plants or grow invasively on tomato fruit tissue. These strains were hypersensitive to compounds that interfere with fungal cell wall assembly, produced lemon-like shaped conidia, and showed swollen balloon-like structures in hyphal subapical regions, thickened walls, aberrant septa, and intrahyphal hyphae. Our results suggest that the chsVb gene is likely to function in polarized growth and confirm the critical importance of cell wall integrity in the complex infection process of this fungus.
在维管束萎蔫病菌尖孢镰刀菌番茄专化型中发现了一个新的肌球蛋白样几丁质合酶基因chsVb。对chsVb几丁质合酶2结构域（CS2）推导的氨基酸序列进行系统发育分析表明，ChsVb属于VII类几丁质合酶。ChsVb的肌球蛋白样结构域（MMD）比V类几丁质合酶的MMD短，且不包含典型的ATP结合基序。靶向破坏的单突变体（DeltachsVb）和双突变体（DeltachsV DeltachsVb）无法侵染和定殖番茄植株，也不能在番茄果实组织上进行侵袭性生长。这些菌株对干扰真菌细胞壁组装的化合物高度敏感，产生柠檬形分生孢子，在菌丝亚顶端区域呈现肿胀的气球状结构、细胞壁增厚、隔膜异常以及菌丝内菌丝。我们的结果表明，chsVb基因可能在极性生长中发挥作用，并证实了细胞壁完整性在该真菌复杂感染过程中的至关重要性。
