人类血清可以有效地诱导多态真菌病原体——白色念珠菌的菌丝生长，白色念珠菌会导致严重感染。真菌腺嘌呤环化酶Cyr1p是cAMP/PKA信号传导通路的一个关键组成部分，该通路控制着不同的相关感染性状，包括菌丝的形态形成。然而，目前有关血清菌丝诱导特点及其真菌传感器的机制仍属未知。
在7月17日《细胞—宿主与微生物》（Cell Host & Microbe）发表的一项最新研究中，Xu等人的分析结果表明，活化血清的组分中含有细菌的类肽聚糖（PGN）分子。而有几个纯化和合成的胞壁酰二肽（MDPs）与细菌的类肽聚糖的亚基能够有效地促进白色念珠菌的菌丝生长。
通常情况下，哺乳动物的传感器Nod1和Nod2可以通过LRR域识别PGN的类似物，Xu等人的研究表明，胞壁酰二肽（MDPs）可以通过直接与其LRR域结合来激活Cyr1p。如果在宿主和白色念珠菌感染的肠道内有丰富的PGN存在，新的研究结果对这种病原体的感染机制具有重大意义。（生物谷Bioon.com）
生物谷推荐原始出处：
Cell Host & Microbe，Vol 4, 28-39, 17 July 2008，Xiao-Li Xu, Yong Zhu, and Yue Wang
Bacterial Peptidoglycan Triggers Candida albicans Hyphal Growth by Directly Activating the Adenylyl Cyclase Cyr1p
Xiao-Li Xu,1,2 Raymond Teck Ho Lee,1,2 Hao-Ming Fang,1,2 Yan-Ming Wang,1 Rong Li,1 Hao Zou,1 Yong Zhu,1 and Yue Wang1, Bioon
1 Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (ASTAR), 61 Biopolis Drive, Proteos, Singapore 138673
Corresponding author
Yue Wang
mcbwangy@imcb.a-star.edu.sg
Summary
Human serum potently induces hyphal development of the polymorphic fungal pathogen Candida albicans, a phenotype that contributes critically to infections. The fungal adenylyl cyclase Cyr1p is a key component of the cAMP/PKA-signaling pathway that controls diverse infection-related traits, including hyphal morphogenesis. However, identity of the serum hyphal inducer(s) and its fungal sensor remain unknown. Our initial analyses of active serum fractions revealed signs of bacterial peptidoglycan (PGN)-like molecules. Here, we show that several purified and synthetic muramyl dipeptides (MDPs), subunits of PGN, can strongly promote C. albicans hyphal growth. Analogous to PGN recognition by the mammalian sensors Nod1 and Nod2 through their leucine-rich-repeat (LRR) domain, we show that MDPs activate Cyr1p by directly binding to its LRR domain. Given the abundance of PGN in the intestine, a natural habitat and invasion site for C. albicans, our findings have important implications for the mechanisms of infection by this pathogen.
