Department of Microbiology, The University of Alabama at Birmingham, Birmingham, AL, USA.
Infectious Diseases and Genomic Medicine Group, J. Craig Venter Institute, Rockville, MD, USA.
Cell Rep. 2021 Jun 15;35(11):109267. doi: 10.1016/j.celrep.2021.109267.
Streptococcus pneumoniae (Spn) alone and during co-infection with influenza A virus (IAV) can result in severe pneumonia with mortality. Pneumococcal surface protein A (PspA) is an established virulence factor required for Spn evasion of lactoferricin and C-reactive protein-activated complement-mediated killing. Herein, we show that PspA functions as an adhesin to dying host cells. We demonstrate that PspA binds to host-derived glyceraldehyde-3-phosphate dehydrogenase (GAPDH) bound to outward-flipped phosphatidylserine residues on dying host cells. PspA-mediated adhesion was to apoptotic, pyroptotic, and necroptotic cells, but not healthy lung cells. Using isogenic mutants of Spn, we show that PspA-GAPDH-mediated binding to lung cells increases pneumococcal localization in the lower airway, and this is enhanced as a result of pneumolysin exposure or co-infection with IAV. PspA-mediated binding to GAPDH requires amino acids 230-281 in its α-helical domain with intratracheal inoculation of this PspA fragment alongside the bacteria reducing disease severity in an IAV/Spn pneumonia model.
肺炎链球菌(Spn)单独感染或与甲型流感病毒(IAV)共同感染可导致严重肺炎和死亡率。肺炎球菌表面蛋白 A(PspA)是一种已被证实的毒力因子,可使 Spn 逃避乳铁蛋白和 C 反应蛋白激活的补体介导的杀伤。在此,我们发现 PspA 可作为一种黏附素作用于濒死宿主细胞。我们证明 PspA 可与宿主来源的甘油醛-3-磷酸脱氢酶(GAPDH)结合,而 GAPDH 结合在濒死宿主细胞外翻的磷脂酰丝氨酸残基上。PspA 介导的黏附作用于凋亡、细胞焦亡和坏死细胞,但不作用于健康的肺细胞。通过 Spn 的同工型突变体,我们发现 PspA-GAPDH 介导的与肺细胞的结合增加了肺炎链球菌在下呼吸道的定位,并且这种结合由于肺炎球菌溶素的暴露或与 IAV 的共同感染而增强。PspA 与 GAPDH 的结合需要其α螺旋结构域中的 230-281 个氨基酸,通过气管内接种该 PspA 片段以及细菌,可以降低 IAV/Spn 肺炎模型的疾病严重程度。