Identification of a galactose-specific flocculin essential for non-sexual flocculation and filamentous growth in Schizosaccharomyces pombe
Identification of a galactose-specific flocculin essential for non-sexual flocculation and filamentous growth in Schizosaccharomyces pombe
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DOI：
10.1111/j.1365-2958.2011.07908.x
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发表时间：
2011-12-01
影响因子：
3.6
通讯作者：
Takegawa, Kaoru
中科院分区：
文献类型：
--
作者：
Matsuzawa, Tomohiko;Morita, Tomotake;Takegawa, Kaoru
尽管分裂酵母裂糖酵母（Schizosaccharomyces pombe）的各种突变株都表现出无性絮凝，但人们对这种现象的机制基础知之甚少，也没有发现编码相关絮凝蛋白的基因。在出芽酵母中，转录因子Flo8控制着一些参与无性絮凝的基因的表达。我们发现过表达酿酒酵母FLO8可诱导pombe的无性絮凝。这种无性别的絮凝是Ca2+依赖的，并且被半乳糖的添加所抑制，但不被甘露糖、葡萄糖或蔗糖所抑制。在flo8过表达菌株中，特异性诱导了gsf2+（半乳糖特异性絮凝）基因。gsf2+基因在lkh1？, tup12 ?gsf1突变体，均表现出依赖gsf2+的无性絮凝。我们发现Gsf2的n端区域在介导细胞相互作用中识别半乳糖。gsf2+的破坏也破坏了野生型菌株在低铵培养基中培养的粘附表型和侵袭性生长。在裂变酵母中新发现的絮凝蛋白Gsf2不仅是非性絮凝所必需的，而且还需要通过识别细胞表面糖结合物上的半乳糖残基来粘附和丝状生长。
Although various mutant strains of the fission yeast Schizosaccharomyces pombe exhibit non-sexual flocculation, little is known about the mechanistic basis for this phenomenon, nor have genes encoding the implicated flocculin been identified. In the budding yeast Saccharomyces cerevisiae, the transcription factor Flo8 controls expression of some of the genes involved in non-sexual flocculation. We have found that overexpression of S. cerevisiae FLO8 induced non-sexual flocculation in S. pombe. This non-sexual flocculation was Ca2+-dependent, and was inhibited by addition of galactose, but not by mannose, glucose or sucrose. In the FLO8-overexpressing strain, a gene designated gsf2+ (galactose-specific flocculation) was specifically induced. The gsf2+ gene was also highly expressed in lkh1?, tup12? and gsf1 mutants, all of which exhibited non-sexual flocculation dependent on gsf2+. We show that the N-terminal region of Gsf2 recognizes galactose in mediating cellcell interaction. Disruption of gsf2+ also abolished the adhesion phenotype and invasive growth of the wild-type strain cultured in low ammonium medium. The newly identified flocculin Gsf2 in fission yeast was not only required for non-sexual flocculation but was also required for adhesion and filamentous growth through recognition of galactose residues on cell surface glycoconjugates.