Blowing epithelial cell bubbles with GumB: ShlA-family pore-forming toxins induce blebbing and rapid cellular death in corneal epithelial cells
Fig 5
S. marcescens gumB gene is necessary but not sufficient for the bleb and cytotoxicity induction, and the gumB mutant strain defect is complemented by igaA-family genes and shlBA.
(A,B) Confocal micrographs of primary human corneal and HCLE cells imaged with differential interference contrast (DIC) and calcein AM viability stain after exposure to bacteria for 2 h at MOI = 50, except where noted. Yellow arrows indicate blebs extending from corneal cells. (A) Confocal micrographs of HCLE cells with S. marcescens strain K904, mutant strains, or E. coli strain EC100D pir-116. Vector = pMQ132; pshlBA = pMQ541; pgumB = pMQ480. The percent of bleb positive cells induced by select bacteria are shown. (B) HCLE cells exposed to the gumB mutant strain (MOI = 50) with plasmid-borne igaA-family genes from S. marcescens (pgumB = pMQ480), S. enterica (pigaA = pMQ530), K. pneumoniae (pkumO = pMQ529), E. coli (pyrfF = pMQ531), or P. mirabilis (pumoB = pMQ600). Vector = pMQ132. (C) Relative gene expression using the ΔΔCT method depicts shlA transcript levels in the wild type (K904) and ΔgumB mutant strains at OD600 = 3; *p = 0.0286, Mann-Whitney test.