Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, The Ohio State University School of Medicine, Columbus OH, USA.
Front Cell Infect Microbiol. 2012 Apr 3;2:42. doi: 10.3389/fcimb.2012.00042. eCollection 2012.
Non-typeable Haemophilus influenzae (NTHI) is a common commensal bacterium that resides in the human upper respiratory tract of healthy individuals. NTHI is also a known causative agent of multiple diseases including sinusitis, otitis media, as well as exacerbates disease severity of patients with cystic fibrosis and chronic obstructive pulmonary disease. We have previously shown that the Sap transporter mediates resistance to host antimicrobial peptides (AMPs) and import of the iron-containing compound heme. Here, we analyzed the contribution of the Sap structural ATPase protein, SapF, in these essential functions. In contrast to SapD, SapF was dispensable for NTHI survival when exposed to AMPs in vitro. SapF was responsible for heme utilization and recovery of depleted internal heme-iron stores. Further, a loss of SapF resulted in morphological plasticity and enhanced community development and biofilm architecture, suggesting the potential role of heme-iron availability in coordinating the complexity of NTHI biofilm architecture. SapF was required for colonization of the nasopharynx and acute infection of the middle ear, as SapF deficiency correlated with a statistically significant decrease in NTHI persistence in vivo. These data suggest that SapF is required for proper heme utilization which directly impacts NTHI survival. Thus, these studies further support a role for the Sap complex in the transport of multiple substrates and further defines substrate specificity for the two ATPase subunits. Given the multiple essential functions provided by the Sap transporter, this complex could prove to be an effective therapeutic target for the treatment of NTHI diseases.
无荚膜流感嗜血杆菌（NTHI）是一种常见的共生细菌，存在于健康个体的上呼吸道中。NTHI 也是多种疾病的已知病原体，包括鼻窦炎、中耳炎，并且会加重囊性纤维化和慢性阻塞性肺疾病患者的疾病严重程度。我们之前已经表明，Sap 转运体介导对宿主抗菌肽（AMPs）的抗性和含铁化合物血红素的摄取。在这里，我们分析了 Sap 结构 ATP 酶蛋白 SapF 在这些基本功能中的作用。与 SapD 不同，SapF 在体外暴露于 AMP 时对 NTHI 的存活不是必需的。SapF 负责利用血红素和恢复耗尽的内部血红素铁储存。此外，SapF 的缺失导致形态可塑性增强，群落发育和生物膜结构增强，表明血红素铁可用性在协调 NTHI 生物膜结构的复杂性方面具有潜在作用。SapF 是鼻咽定植和中耳急性感染所必需的，因为 SapF 缺陷与 NTHI 在体内的持久性统计学显着降低相关。这些数据表明，SapF 是适当利用血红素所必需的，这直接影响 NTHI 的存活。因此，这些研究进一步支持 Sap 复合物在多种底物的转运中的作用，并进一步定义了两个 ATP 酶亚基的底物特异性。鉴于 Sap 转运体提供的多种必需功能，该复合物可能成为治疗 NTHI 疾病的有效治疗靶点。
