Orientia tsutsugamushi Ank-host interactions in scrub typhus pathogenesis

恙虫病东方体在恙虫病发病机制中的Ank-宿主相互作用

• 批准号: 10571846
• 负责人: Jason A Carlyon
• 金额: $ 57.32万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-15 至 2027-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10571846
• 关键词: ANK1 gene; Ankyrin Repeat; Annual Reports; Antigen-Presenting Cells; Bacteria; Binding; Biological Assay; Blood Vessels; C-terminal; Case Study; Cell Nucleus; Cell physiology; Cells; Cellular biology; Cessation of life; Complex; Coupled; Cytoplasm; Data; Defense Mechanisms; Development; Disease; Dominant-Negative Mutation; Endothelial Cells; Etiology; Evolution; F Box Domain; F-Box Motifs; Gene Expression; Genes; Genetic; Hospitalization; Immune response; Immunity; Immunoprecipitation; Impairment; Infection; Invaded; Knowledge; Leukocytes; Life; Link; Lysine; Mammalian Cell; Mass Spectrum Analysis; Mediating; Microbe; Mus; Natural Immunity; Nature; Organ failure; Orientia tsutsugamushi; Outcome; Pathogenesis; Pathway interactions; Persons; Phosphotransferases; Preventive vaccine; Proteins; Role; SKP Cullin F-Box Protein Ligases; Scrub Typhus; System; Testing; Time; Toxic effect; Trans-Activators; Trees; Ubiquitin; Ubiquitination; Virulence; Virulence Factors; War; Yeasts; adaptive immunity; cell type; cohort; design; functional mimics; functional outcomes; gain of function; global health; immunoregulation; in vivo; inhibitor; innovation; insight; microbial; mimicry; multicatalytic endopeptidase complex; novel; pathogen; pathogenic bacteria; prevent; protein protein interaction; screening; success; therapeutic target; ubiquitin ligase

Scrub typhus is an emerging and potentially fatal global health threat. Approximately one million new cases are reported annually. The etiologic agent is Orientia tsutsugamushi, an obligate intracellular bacterium that infects leukocytes and endothelial cells resulting in vascular collapse, organ failure, and death. Treatment options are limited and no preventative vaccine exists. The success of O. tsutsugamushi as a pathogen lies in its ability to modulate host immunity and other pathways. The responsible mechanisms are unknown, highlighting the need for a better understanding of scrub typhus host-pathogen interactions. The ankyrin repeat (AR) is a protein- protein interaction motif that is prevalent throughout nature. O. tsutsugamushi has one of the largest arsenals of AR-containing effectors (Anks) among bacteria and expresses all of them during infection, underscoring their importance for intracellular survival and virulence. Most Orientia Anks carry a C-terminal F-box motif that co-opts host ubiquitin ligases. We discovered that O. tsutsugamushi Ank1 and Ank6 impede the NF-κB pathway in an AR- and F-box-dependent manner. Both bind and prevent the degradation of host NF-κB inhibitor, p105. Ank1 and Ank6 ARs mimic those of EPRAP, a host protein that stabilizes p105, and ubiquitinate Crybg3, a host kinase that influences p105 stability. Further screening revealed that a total of 13 Anks antagonize NF-κB, some of which bind p105 and others do not. Thus, multiple Anks inhibit NF-κB by distinct, overlapping mechanisms. We found that O. tsutsugamushi lowers MHC-I levels by orchestrating proteasomal degradation of NLRC5, a transactivator of MHC-I gene expression, and linked this phenomenon to Ank5. How Ank1, Ank5, and Ank6 inhibit innate and adaptive immunity is poorly characterized. We established that Orientia Anks alter the host cell ubiquitome, but the extent of this strategy, identity of modified targets, and infection outcomes are unexplored. Finally, other Anks target unknown eukaryotic pathways that also likely influence O. tsutsugamushi pathobiology. To fill these knowledge gaps, we will decipher the mechanisms by which Anks inhibit NF-κB and use two innovative screens that circumvent O. tsutsugamushi genetic intractability as part of our approach (Aim 1); dissect how Ank5 promotes NLRC5 degradation to block MHC-I expression (Aim 2); and identify new host cell pathways and ubiquitome changes that Anks modulate (Aim 3). The contribution of each newly discovered host- Ank interaction to O. tsutsugamushi pathogenesis will be interrogated. Overall, we will advance fundamental understanding of O. tsutsugamushi-host interactions, define novel mechanisms by which intracellular pathogens modulate immunity, identify new scrub typhus therapeutic targets, and benefit the bourgeoning concept of designed AR proteins as biomedicals to have a broad and powerful impact.

丛林斑疹伤寒是一种新出现的、可能致命的全球健康威胁。大约有100万新病例