c. elegans swan-1 binds to egl-9 and regulates hif-1-mediated resistance to the bacterial pathogen pseudomonas aeruginosa pao1秀丽隐杆线虫swan-1结合egl-9和调节hif-1-mediated抗绿脓假单胞菌pao1.pdfVIP

C. elegans SWAN-1 Binds to EGL-9 and Regulates HIF-1- Mediated Resistance to the Bacterial Pathogen Pseudomonas aeruginosa PAO1 Zhiyong Shao., Yi Zhang., Qi Ye, Jenifer Neeta Saldanha, Jo Anne Powell-Coffman* Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa, United States of America Abstract Pseudomonas aeruginosa is a nearly ubiquitous human pathogen, and infections can be lethal to patients with impaired respiratory and immune systems. Prior studies have established that strong loss-of-function mutations in the egl-9 gene protect the nematode C. elegans from P. aeruginosa PAO1 fast killing. EGL-9 inhibits the HIF-1 transcription factor via two pathways. First, EGL-9 is the enzyme that targets HIF-1 for oxygen-dependent degradation via the VHL-1 E3 ligase. Second, EGL-9 inhibits HIF-1-mediated gene expression through a VHL-1-independent mechanism. Here, we show that a loss-of- function mutation in hif-1 suppresses P. aeruginosa PAO1 resistance in egl-9 mutants. Importantly, we find stabilization of HIF-1 protein is not sufficient to protect C. elegans from P. aeruginosa PAO1 fast killing. However, mutations that inhibit both EGL-9 pathways result in higher levels of HIF-1 activity and confer resistance to the pathogen. Using forward genetic screens, we identify additional mutations that confer resistance to P. aeruginosa. In genetic backgrounds that stabilize C. elegans HIF-1 protein, loss-of-function mutations in swan-1 increase the expression of hypoxia response genes and protect C. elegans from P. aeruginosa fast killing. SWAN-1 is an evolutionarily conserved WD-repeat protein belonging to the AN11 family. Yeast two-hybrid and co-immunoprecipitation assays show that EGL-9 forms a complex with SWAN-1. Additionally, we present genetic evidence that the DYRK kinase MBK-1 acts downstr