Ishii Kenichi, Adachi Tatsuo, Hara Takashi, Hamamoto Hiroshi, Sekimizu Kazuhisa
Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan.
Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan.
J Invertebr Pathol. 2014 Mar;117:61-7. doi: 10.1016/j.jip.2014.02.001. Epub 2014 Feb 12.
Injection of culture supernatant of Serratia marcescens, a Gram-negative bacterium pathogenic to a wide range of host animals including insects and mammals, into the hemolymph of silkworm (Bombyx mori) larvae led to continuous flow of the hemolymph (blood of insects) from the injection site. The amount of hemolymph lost within 60 min reached 15-20% of the total larval weight. Using a bioassay with live silkworms, we purified Serralysin, a metalloprotease that requires divalent cations for its activity, as the factor responsible for the promotion of hemolymph bleeding from the culture supernatant of S. marcescens. Recombinant protein also induced hemolymph bleeding in silkworms. Moreover, the culture supernatant of an S. marcescens disruption mutant of the ser gene showed attenuated ability to promote hemolymph bleeding. In addition, this bleeding-promoting activity of the S. marcescens culture supernatant was attenuated by disruption of the wecA gene, which is involved in the biosynthesis of the lipopolysaccharide O-antigen. These findings suggest that Serralysin metalloprotease contributes to the pathogenesis of S. marcescens by inhibiting wound healing, which leads to a massive loss of hemolymph from silkworm larvae.
将粘质沙雷氏菌（一种对包括昆虫和哺乳动物在内的多种宿主动物致病的革兰氏阴性细菌）的培养上清液注射到家蚕（Bombyx mori）幼虫的血淋巴中，会导致血淋巴（昆虫的血液）从注射部位持续流出。60分钟内损失的血淋巴量达到幼虫总重量的15 - 20%。通过对活蚕进行生物测定，我们纯化出了一种金属蛋白酶丝氨酸蛋白酶（Serralysin），其活性需要二价阳离子，它是粘质沙雷氏菌培养上清液中促进血淋巴出血的因子。重组蛋白也会在家蚕中引发血淋巴出血。此外，ser基因的粘质沙雷氏菌破坏突变体的培养上清液促进血淋巴出血的能力减弱。另外，参与脂多糖O抗原生物合成的wecA基因的破坏会减弱粘质沙雷氏菌培养上清液的这种促出血活性。这些发现表明，丝氨酸蛋白酶金属蛋白酶通过抑制伤口愈合，从而导致家蚕幼虫大量血淋巴流失，在粘质沙雷氏菌的致病过程中发挥作用。
