Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA.
Department of Obstetrics and Gynecology, Virginia Commonwealth University, Richmond, Virginia, USA.
J Bacteriol. 2020 Jun 9;202(13). doi: 10.1128/JB.00162-20.
is a poorly characterized emerging pathogen that has been implicated in amnionitis and urethritis. We found that damages fetal membranes, and we identified and purified a cytotoxic exotoxin that lyses human red blood cells and damages cells from fetal membranes. The gene appears to be cotranscribed with a second gene that encodes a protein with identity to two-partner system transporters, suggesting that it is the "A," or secreted component of a type Vb system. The toxin is 1,881 amino acids with a molecular weight of approximately 200 kDa. It binds to red blood cell membranes and forms pores with a diameter of 2.0 to 3.0 nm, resulting in osmolysis. Because it appears to be the "A" or passenger component of a two-partner system, we propose to name this novel cytotoxin/hemolysin CptA for cytopathogenic toxin component A. is a very poorly characterized emerging pathogen that can affect pregnancy outcome and cause urethritis and other infections. To date, nothing is known about its virulence factors or pathogenesis. We have identified and isolated a cytotoxin, named CptA for cytopathogenic toxin, component A, that is produced by CptA is capable of permeabilizing chorionic trophoblasts and lysing human red blood cells and, thus, may play a role in virulence. Except for small domains conserved among two-partner secretion system passenger proteins, the cytotoxin exhibits little amino acid sequence homology to known toxins. In this study, we demonstrate the pore-forming activity of this novel toxin.
是一种特征尚不明确的新兴病原体，与羊膜炎和尿道炎有关。我们发现破坏了胎膜，并鉴定和纯化了一种细胞毒性外毒素，该毒素可裂解人红细胞并破坏胎膜细胞。该基因似乎与编码与双组分系统转运蛋白具有同源性的第二种基因共转录，表明它是一种 Vb 型系统的“A”或分泌成分。该毒素由 1881 个氨基酸组成，分子量约为 200 kDa。它与红细胞膜结合并形成直径为 2.0 至 3.0nm 的孔，导致渗透性溶解。由于它似乎是双组分系统的“A”或乘客成分，我们提议将这种新型细胞毒素/溶血素 CptA 命名为细胞病变毒素成分 A。是一种特征非常不明确的新兴病原体，可影响妊娠结局并引起尿道炎和其他感染。迄今为止，人们对其毒力因子或发病机制一无所知。我们已经鉴定并分离出一种细胞毒素，命名为 CptA，即细胞病变毒素的 A 成分，由 CptA 产生，能够渗透绒毛滋养层并裂解人红细胞，因此可能在毒力中起作用。除了双组分分泌系统乘客蛋白中保守的小结构域外，细胞毒素与已知毒素的氨基酸序列同源性很小。在这项研究中，我们证明了这种新型毒素的形成孔活性。
