Department of Microbiology and Medical Zoology, Medical Sciences Campus, University of Puerto Rico, San Juan PR, USA.
BMC Microbiol. 2012 Sep 7;12:194. doi: 10.1186/1471-2180-12-194.
Adaptive responses in fungi result from the interaction of membrane receptors and extracellular ligands. Many different classes of receptors have been described in eukaryotic cells. Recently a new family of receptors classified as belonging to the progesterone-adiponectin receptor (PAQR) family has been identified. These receptors have the seven transmembrane domains characteristic of G-protein coupled receptors, but their activity has not been associated directly to G proteins. They share sequence similarity to the eubacterial hemolysin III proteins.
A new receptor, SsPAQR1 (Sporothrix schenckii progesterone-adiponectinQ receptor1), was identified as interacting with Sporothrix schenckii G protein alpha subunit SSG-2 in a yeast two-hybrid assay. The receptor was identified as a member of the PAQR family. The cDNA sequence revealed a predicted ORF of 1542 bp encoding a 514 amino acids protein with a calculated molecular weight of 57.8 kDa. Protein domain analysis of SsPAQR1 showed the 7 transmembrane domains (TM) characteristic of G protein coupled receptors and the presence of the distinctive motifs that characterize PAQRs. A yeast-based assay specific for PAQRs identified progesterone as the agonist. S. schenckii yeast cells exposed to progesterone (0.50 mM) showed an increase in intracellular levels of 3', 5' cyclic adenosine monophosphate (cAMP) within the first min of incubation with the hormone. Different progesterone concentrations were tested for their effect on the growth of the fungus. Cultures incubated at 35°C did not grow at concentrations of progesterone of 0.05 mM or higher. Cultures incubated at 25°C grew at all concentrations tested (0.01 mM-0.50 mM) with growth decreasing gradually with the increase in progesterone concentration.
This work describes a receptor associated with a G protein alpha subunit in S. schenckii belonging to the PAQR family. Progesterone was identified as the ligand. Exposure to progesterone increased the levels of cAMP in fungal yeast cells within the first min of incubation suggesting the connection of this receptor to the cAMP signalling pathway. Progesterone inhibited the growth of both the yeast and mycelium forms of the fungus, with the yeast form being the most affected by the hormone.
真菌的适应性反应是由膜受体和细胞外配体相互作用产生的。在真核细胞中已经描述了许多不同类别的受体。最近，一类新的受体被归类为孕激素-脂联素受体（PAQR）家族。这些受体具有 G 蛋白偶联受体的七个跨膜结构域特征，但它们的活性尚未与 G 蛋白直接相关。它们与真细菌溶血素 III 蛋白具有序列相似性。
在酵母双杂交试验中，发现了一种新的受体，SsPAQR1（Sporothrix schenckii 孕激素-脂联素 Q 受体 1）与 Sporothrix schenckii G 蛋白 alpha 亚基 SSG-2 相互作用。该受体被鉴定为 PAQR 家族的成员。cDNA 序列显示，ORF 预测为 1542bp，编码一个 514 个氨基酸的蛋白质，计算分子量为 57.8kDa。对 SsPAQR1 的蛋白结构域分析表明，它具有 G 蛋白偶联受体的 7 个跨膜结构域（TM）和特征性的 PAQR 特征基序。针对 PAQRs 的酵母测定特异性地鉴定出孕激素为激动剂。用激素孵育 0.50mM 孕酮后，酵母细胞中的 3'，5'环腺苷酸单磷酸（cAMP）的细胞内水平在孵育的第一分钟内增加。测试了不同的孕激素浓度对真菌生长的影响。在 35°C 孵育的培养物在 0.05mM 或更高浓度的孕酮下不生长。在 25°C 孵育的培养物在所有测试浓度（0.01mM-0.50mM）下均生长，随着孕酮浓度的增加，生长逐渐减少。
本研究描述了一种与 S. schenckii 中的 G 蛋白 alpha 亚基相关的属于 PAQR 家族的受体。鉴定出孕激素为配体。暴露于孕酮后，在孵育的第一分钟内真菌酵母细胞中的 cAMP 水平增加，表明该受体与 cAMP 信号通路的连接。孕酮抑制真菌的酵母和菌丝两种形式的生长，酵母形式受激素影响最大。
