Processing of Candida albicans Ece1p Is Critical for Candidalysin Maturation and Fungal Virulence.
Processing of Candida albicans Ece1p Is Critical for Candidalysin Maturation and Fungal Virulence.
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白色念珠菌ECE1P的处理对于念珠菌素的成熟和真菌毒力至关重要。
DOI：
10.1128/mbio.02178-17
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发表时间：
2018-01-23
期刊：
影响因子：
6.4
通讯作者：
Naglik JR
中科院分区：
文献类型：
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作者：
Richardson JP;Mogavero S;Moyes DL;Blagojevic M;Krüger T;Verma AH;Coleman BM;De La Cruz Diaz J;Schulz D;Ponde NO;Carrano G;Kniemeyer O;Wilson D;Bader O;Enoiu SI;Ho J;Kichik N;Gaffen SL;Hube B;Naglik JR
白色念珠菌是一种机会性真菌病原体负责浅表和危及生命的感染在人类。在粘膜感染期间，白色念珠菌经历了从酵母菌到侵入丝状菌丝的形态转变，分泌念珠菌素，一种31氨基酸的肽毒素。念珠菌素损伤上皮细胞膜，刺激活化蛋白1 （AP-1）转录因子c-Fos（通过p38 -丝裂原活化蛋白激酶[MAPK]）和MAPK磷酸酶MKP1（通过细胞外信号调节激酶1和2 [ERK1/2] -MAPK），分别触发和调节促炎细胞因子反应。念珠菌素毒素作为一个离散的隐序列存在于一个较大的271个氨基酸的亲本前蛋白Ece1p中。在这里，我们证明了类似于酮蛋白的蛋白酶，而不是分泌的天冬氨酸蛋白酶，启动了Ece1p的两步翻译后加工，以产生候选酵素。在Arg61和Arg93之后，而不是在Ece1p的其他加工位点之后，需要kex2p介导的Ece1p蛋白水解才能从Ece1p中产生未成熟的假丝酵素，然后通过kex2p介导的去除一个羧基精氨酸残基来产生成熟的假丝酵素。携带Arg61和/或Arg93突变的白色念珠菌菌株在体外不分泌念珠菌素，不能诱导上皮损伤和炎症反应，并且在口咽念珠菌病小鼠模型中显示出减弱的毒力。这些观察结果表明，酵素样蛋白酶对白色念珠菌Ece1p的酶处理是念珠菌素生产和真菌致病性所需的关键步骤。白色念珠菌是一种机会性真菌病原体，可引起全世界数百万人的粘膜感染。成功的感染需要分泌念珠菌素，这是人类真菌病原体中发现的第一种细胞溶解肽毒素。念珠菌素来源于其亲本蛋白Ece1p。在这里，我们确定了Ece1p中对加工和生产候选菌素至关重要的两个关键氨基酸。这些残基的突变使白色念珠菌在体内不能引起上皮损伤并显著减少粘膜感染。重要的是，候选酵素的产生需要两个单独的酶促事件。第一种是由Kex2p处理Ece1p，产生不成熟的候选菌素，然后由Kex1p进一步处理产生成熟的毒素。这些观察结果确定了粘膜表面白色念珠菌致病性的重要步骤。
Candida albicans is an opportunistic fungal pathogen responsible for superficial and life-threatening infections in humans. During mucosal infection, C. albicans undergoes a morphological transition from yeast to invasive filamentous hyphae that secrete candidalysin, a 31-amino-acid peptide toxin required for virulence. Candidalysin damages epithelial cell plasma membranes and stimulates the activating protein 1 (AP-1) transcription factor c-Fos (via p38–mitogen-activated protein kinase [MAPK]), and the MAPK phosphatase MKP1 (via extracellular signal-regulated kinases 1 and 2 [ERK1/2]–MAPK), which trigger and regulate proinflammatory cytokine responses, respectively. The candidalysin toxin resides as a discrete cryptic sequence within a larger 271-amino-acid parental preproprotein, Ece1p. Here, we demonstrate that kexin-like proteinases, but not secreted aspartyl proteinases, initiate a two-step posttranslational processing of Ece1p to produce candidalysin. Kex2p-mediated proteolysis of Ece1p after Arg61 and Arg93, but not after other processing sites within Ece1p, is required to generate immature candidalysin from Ece1p, followed by Kex1p-mediated removal of a carboxyl arginine residue to generate mature candidalysin. C. albicans strains harboring mutations of Arg61 and/or Arg93 did not secrete candidalysin, were unable to induce epithelial damage and inflammatory responses in vitro, and showed attenuated virulence in vivo in a murine model of oropharyngeal candidiasis. These observations identify enzymatic processing of C. albicans Ece1p by kexin-like proteinases as crucial steps required for candidalysin production and fungal pathogenicity. Candida albicans is an opportunistic fungal pathogen that causes mucosal infection in millions of individuals worldwide. Successful infection requires the secretion of candidalysin, the first cytolytic peptide toxin identified in any human fungal pathogen. Candidalysin is derived from its parent protein Ece1p. Here, we identify two key amino acids within Ece1p vital for processing and production of candidalysin. Mutations of these residues render C. albicans incapable of causing epithelial damage and markedly reduce mucosal infection in vivo. Importantly, candidalysin production requires two individual enzymatic events. The first involves processing of Ece1p by Kex2p, yielding immature candidalysin, which is then further processed by Kex1p to produce the mature toxin. These observations identify important steps for C. albicans pathogenicity at mucosal surfaces.