Sekiya Hiroshi, Okada Maho, Tamai Eiji, Shimamoto Toshi, Shimamoto Tadashi, Nariya Hirofumi
Department of Infectious Disease, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime 790-8578, Japan.
Laboratory of Food Microbiology and Hygiene, Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama-cho, Higashihiroshima, Hiroshima 739-8528, Japan.
Antibiotics (Basel). 2021 Mar 1;10(3):245. doi: 10.3390/antibiotics10030245.
is an often-harmful intestinal bacterium that causes various diseases ranging from food poisoning to life-threatening fulminant disease. Potential treatments include phage-derived endolysins, a promising family of alternative antimicrobial agents. We surveyed the genome of the st13 strain and identified an endolysin gene, , in the phage remnant region. Psa has an N-terminal catalytic domain that is homologous to the amidase_2 domain, and a C-terminal domain of unknown function. and gene derivatives encoding various Psa subdomains were cloned and expressed in as N-terminal histidine-tagged proteins. Purified His-tagged full-length Psa protein (Psa-his) showed -specific lytic activity in turbidity reduction assays. In addition, we demonstrated that the uncharacterized C-terminal domain has cell wall-binding activity. Furthermore, cell wall-binding measurements showed that Psa binding was highly specific to . These results indicated that Psa is an amidase endolysin that specifically lyses ; the enzyme's specificity is highly dependent on the binding of the C-terminal domain. Moreover, Psa was shown to have a synergistic effect with another -specific endolysin, Psm, which is a muramidase that cleaves peptidoglycan at a site distinct from that targeted by Psa. The combination of Psa and Psm may be effective in the treatment and prevention of infections.
是一种常具危害性的肠道细菌，可引发从食物中毒到危及生命的暴发性疾病等各种病症。潜在的治疗方法包括噬菌体衍生的内溶素，这是一类有前景的替代抗菌剂。我们对st13菌株的基因组进行了研究，并在噬菌体残余区域鉴定出一个内溶素基因，即Psa。Psa具有一个与酰胺酶_2结构域同源的N端催化结构域，以及一个功能未知的C端结构域。编码各种Psa亚结构域的Psa和基因衍生物被克隆，并作为N端带组氨酸标签的蛋白在中表达。纯化的带组氨酸标签的全长Psa蛋白（Psa-his）在浊度降低试验中显示出特异性裂解活性。此外，我们证明了未表征的C端结构域具有细胞壁结合活性。此外，细胞壁结合测量表明Psa的结合对具有高度特异性。这些结果表明Psa是一种特异性裂解的酰胺酶内溶素；该酶的特异性高度依赖于C端结构域的结合。此外，Psa被证明与另一种特异性内溶素Psm具有协同作用，Psm是一种在与Psa靶向位点不同的位点切割肽聚糖的溶菌酶。Psa和Psm的组合可能对感染的治疗和预防有效。
