The Escherichia coli uropathogenic-specific-protein-associated immunity protein 3 (Imu3) has nucleic acid -binding activity

Abstract

BackgroundThe Escherichia coli uropathogenic-specific protein (Usp) is a bacteriocin-like genotoxin, active against mammalian cells and associated with E. coli strains that provoke pyelonephritis, prostatitis and bacteraemia. Usp is encoded by a small pathogenicity island with three downstream small open reading frames (Imu1-3) that are believed to provide immunity to the producer. To prevent host suicide, colicins, bacteriocins of E. coli, form tight complexes with their cognate immunity proteins. Colicin – immunity protein complexes are among the strongest protein complexes known. Here, the Usp associated immunity protein 3 (Imu3) was partially characterized to gain insight into its role and mechanism of activity.ResultsIsolation and partial characterisation of the Usp-associated immunity protein-3 (Imu3) revealed that, while Usp and Imu3 do not form a high affinity complex, Imu3 exhibits DNA and RNA binding activity. Imu3 was also shown to protect DNA against degradation by colicin E7.ConclusionsOur data infer that nonspecific DNA binding of the Imu3 immunity protein, prevents suicide of E. coli producing the genotoxin Usp.

Mathematical model accurately predicts protein release from an affinity-based delivery system

“…A change in predicted release profile was only observed when physically irrelevant values were used for k on and k off (10 −4 M −1 s −1 and 10 −8 s −1 , respectively; Fig. 4, purple curve) [34,35]. This demonstrates the importance of using physically relevant terms in simulations.…”

“…If gel thickness is kept constant at 4 mm, as in our experiments, a k off of b10 −7 s −1 is required for β ≈ 1. This translates to a complex with a lifetime of~3 months, stronger than the strongest known protein-protein complexes of colicin-immunity proteins which have a lifetime of 2 weeks [34,35]. However, if gel thickness is sufficiently decreased, it is possible to achieve β ≪ 1 for physically relevant k off values.…”

Sensing Bacterial-Induced DNA Damaging Effects via Natural Killer Group 2 Member D Immune Receptor: From Dysbiosis to Autoimmunity and Carcinogenesis

“…Escherichia coli uropathogenic-specific protein (Usp) is another bacterial toxin that induces genotoxic stress and activates DDR in exposed cells. This genotoxin is produced by E. coli strains associated with pyelonephritis, prostatitis, and bacteremia ( 87 , 88 ). Purified Usp cleaves linearized naked DNA in vitro and causes DNA fragmentation in mammalian cells ( 28 ).…”

The Role And Importance Of Selected Virulence Factors Determining The Pathogenicity Of Uropathogenic Escherichia Coli Strains

“…Z kolei w przypadku N-terminalnego regionu Usp wykazano podobieństwo do białka systemu sekrecji typu VI, tj. Hcp-like [12,40].…”

“…Bakteriocyny typu nukleaz niszczą komórki docelowe poprzez degradację ich kwasu nukleinowego [67]. Ponadto, postuluje się, że białka OrfU1-3 zaangażowane są w ochronę komórek wytwarzających Usp przed ich własną aktywnością nukleazową oraz nadają bakteriom oporność wobec innych bakteriocyn [12,67]. Szczepy kodujące trzy orfUs są oporne na większą liczbę bakteriocyn, dlatego też mogą być bardziej rozpowszechnione niż bakterie kodujące jedno lub dwa orfUs [67].…”