Mao Xuming, Li Yandong, Wang Huafeng, Cao Fang, Chen Jiangye
State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, SIBS, Chinese Academy of Sciences, Shanghai, China.
FEMS Microbiol Lett. 2008 Aug;285(2):233-41. doi: 10.1111/j.1574-6968.2008.01236.x. Epub 2008 Jun 28.
Candida albicans is a polymorphic human opportunistic pathogen in which the Swi-Snf complex functions as an activator whereas Tup1 acts as a general repressor during the yeast-hyphae transition. In Saccharomyces cerevisiae, the interplay between the Swi-Snf complex and the Tup1-Ssn6 repressive complex regulates the balance between active and repressed chromatin structures of a number of genes. To study the interplay between Candida albicans Swi1 and Tup1 and their effects on morphogenesis, we analyzed phenotypes of swi1/swi1, tup1/tup1 and swi1/swi1 tup1/tup1 mutants under various growth conditions. The swi1/swi1 mutant failed to form true hyphae, whereas the tup1/tup1 mutant exhibited constitutive filamentous growth. Deletion of SWI1 in the tup1/tup1 mutant completely blocked hyphal growth under all the conditions examined. Under aerobic conditions, the swi1/swi1 tup1/tup1 mutant most resembled the swi1/swi1 mutant in phenotype, actin polarization and gene expression pattern. In invaded agar, the double mutant showed similar phenotypes as the swi1/swi1 mutant, while under embedded conditions, it grew as a pseudohypha-like form different from that of the wild-type strain, swi1/swi1 or tup1/tup1 mutants. These results suggest that Swi1 may play a dominant role by antagonizing the repressive effect of the Tup1 on hyphal development in C. albicans.
白色念珠菌是一种多态性人类机会致病菌，在酵母-菌丝转变过程中，Swi-Snf复合物起激活作用，而Tup1起一般阻遏作用。在酿酒酵母中，Swi-Snf复合物与Tup1-Ssn6阻遏复合物之间的相互作用调节许多基因的活性染色质结构与阻遏染色质结构之间的平衡。为了研究白色念珠菌Swi1和Tup1之间的相互作用及其对形态发生的影响，我们分析了swi1/swi1、tup1/tup1和swi1/swi1 tup1/tup1突变体在各种生长条件下的表型。swi1/swi1突变体无法形成真正的菌丝，而tup1/tup1突变体表现出组成型丝状生长。在tup1/tup1突变体中缺失SWI1在所有检测条件下完全阻断了菌丝生长。在有氧条件下，swi1/swi1 tup1/tup1突变体在表型、肌动蛋白极化和基因表达模式上最类似于swi1/swi1突变体。在侵入琼脂中，双突变体表现出与swi1/swi1突变体相似的表型，而在包埋条件下，它以假菌丝样形式生长，不同于野生型菌株、swi1/swi1或tup1/tup1突变体。这些结果表明，在白色念珠菌中Swi1可能通过拮抗Tup1对菌丝发育的阻遏作用发挥主导作用。
