Functional Characterization of Burkholderia pseudomallei Trimeric Autotransporters
Functional Characterization of Burkholderia pseudomallei Trimeric Autotransporters
复制标题
DOI：
10.1128/iai.00526-13
复制
发表时间：
2013-08-01
影响因子：
3.1
通讯作者：
Cotter, Peggy A.
中科院分区：
文献类型：
--
作者：
Campos, Cristine G.;Byrd, Matthew S.;Cotter, Peggy A.
假鼻疽伯克霍尔德氏菌是一种一级选择性病原体，也是类鼻疽病的病原体。类鼻疽病是一种严重的、通常是致命的疾病，其症状包括急性肺炎和感染性休克，以及一种慢性感染，其特征是肺、肝和脾中形成脓肿。自身转运蛋白(AT)是属于V型分泌系统家族的外源蛋白，在多种疾病的发病机制中起着重要作用。假鼻疽杆菌1026b株基因组编码9个可能的三聚体AT蛋白，其中只有4个已被描述。使用生物信息学的方法，我们注释了每个三聚体AT蛋白中的推测结构域，不包括研究得很好的BIMA蛋白，并发现了Burkholderia物种特有的短重复序列，以及出人意料的大比例的AT具有扩展的信号肽区域(ESPR)。为了表征三聚体ATS在发病机制中的作用，我们在八个AT编码基因的每个基因上构建了中断或缺失突变，并评估了所产生的菌株在A549细胞中的黏附、侵袭和斑块形成。大多数ATS(和/或下游编码蛋白)与A549细胞的黏附和有效侵袭有关。利用BALB/c小鼠感染模型，我们确定了每种AT对肺、肝和脾细菌负荷的贡献。在接种后48h，只有一株Bp340：：pDbpaC在肝脏中表现出传播和/或存活的缺陷，这表明在该模型中野生型毒力需要BPAC。
Burkholderia pseudomallei is a tier 1 select agent and the causative agent of melioidosis, a severe and often fatal disease with symptoms ranging from acute pneumonia and septic shock to a chronic infection characterized by abscess formation in the lungs, liver, and spleen. Autotransporters (ATs) are exoproteins belonging to the type V secretion system family, with many playing roles in pathogenesis. The genome of B. pseudomallei strain 1026b encodes nine putative trimeric AT proteins, of which only four have been described. Using a bioinformatic approach, we annotated putative domains within each trimeric AT protein, excluding the well-studied BimA protein, and found short repeated sequences unique to Burkholderia species, as well as an unexpectedly large proportion of ATs with extended signal peptide regions (ESPRs). To characterize the role of trimeric ATs in pathogenesis, we constructed disruption or deletion mutations in each of eight AT-encoding genes and evaluated the resulting strains for adherence to, invasion of, and plaque formation in A549 cells. The majority of the ATs (and/or the proteins encoded downstream) contributed to adherence to and efficient invasion of A549 cells. Using a BALB/c mouse model of infection, we determined the contributions of each AT to bacterial burdens in the lungs, liver, and spleen. At 48 h postinoculation, only one strain, Bp340::pDbpaC, demonstrated a defect in dissemination and/or survival in the liver, indicating that BpaC is required for wildtype virulence in this model.