Broudy Thomas B, Pancholi Vijaykumar, Fischetti Vincent A
Department of Bacterial Pathogenesis and Immunology, Rockefeller University, New York, New York 10021, USA.
Infect Immun. 2002 Jun;70(6):2805-11. doi: 10.1128/IAI.70.6.2805-2811.2002.
The role lysogenic bacteriophage play in the pathogenesis of the host bacterium is poorly understood. In a previous study, we found that streptococcal coculture with human pharyngeal cells resulted in the induction of lysogenic bacteriophage as well as the phage-associated streptococcal pyrogenic exotoxin C (SpeC). In this study, we have determined that in addition to SpeC induction, a number of other streptococcal proteins are also released by the bacteria during coculture with pharyngeal cells. Among these, we identified and characterized a novel 27-kDa secreted protein. Sequence analysis of this novel protein demonstrated it to be encoded by the same lysogenic bacteriophage which harbors speC. Protein sequence analysis revealed varied homologies with several streptococcal DNases. Further biochemical characterization of the recombinantly expressed protein verified it to be a divalent cation-dependent streptococcal phage-encoded DNase (Spd1). Although functionally distinct, SpeC and Spd1 are associated by a number of parameters, including genetic proximity and transcriptional regulation. Finally, we speculate on the induction of phage-encoded DNase (Spd1) enhancing the fitness of both bacteria and phage.
溶原性噬菌体在宿主细菌发病机制中所起的作用目前还知之甚少。在之前的一项研究中，我们发现链球菌与人咽细胞共培养会诱导溶原性噬菌体以及噬菌体相关的链球菌致热外毒素C（SpeC）产生。在本研究中，我们确定，除了诱导SpeC产生外，细菌在与咽细胞共培养过程中还会释放许多其他链球菌蛋白。其中，我们鉴定并表征了一种新的27 kDa分泌蛋白。对这种新蛋白的序列分析表明，它由携带speC的同一溶原性噬菌体编码。蛋白质序列分析显示，它与几种链球菌脱氧核糖核酸酶有不同程度的同源性。对重组表达蛋白的进一步生化特性分析证实它是一种依赖二价阳离子的链球菌噬菌体编码的脱氧核糖核酸酶（Spd1）。尽管功能不同，但SpeC和Spd1在许多参数上相关，包括基因距离和转录调控。最后，我们推测噬菌体编码的脱氧核糖核酸酶（Spd1）的诱导增强了细菌和噬菌体的适应性。
