DSpace Community:https://hdl.handle.net/2440/108302024-03-29T10:51:01Z2024-03-29T10:51:01ZHost-Mediated Copper Stress Is Not Protective against Streptococcus pneumoniae D39 InfectionNeville, S.L.Cunningham, B.A.Maunders, E.A.Tan, A.Watts, J.A.Ganio, K.Eijkelkamp, B.A.Pederick, V.G.Gonzalez de Vega, R.Clases, D.Doble, P.A.McDevitt, C.A.https://hdl.handle.net/2440/1371212023-11-18T16:13:31Z2022-01-01T00:00:00ZTitle: Host-Mediated Copper Stress Is Not Protective against Streptococcus pneumoniae D39 Infection
Author: Neville, S.L.; Cunningham, B.A.; Maunders, E.A.; Tan, A.; Watts, J.A.; Ganio, K.; Eijkelkamp, B.A.; Pederick, V.G.; Gonzalez de Vega, R.; Clases, D.; Doble, P.A.; McDevitt, C.A.
Editor: Sanderson-Smith, M.L.
Abstract: Metal ions are required by all organisms for the chemical processes that support life. However, in excess they can also exert toxicity within biological systems. During infection, bacterial pathogens such as Streptococcus pneumoniae are exposed to host-imposed metal intoxication, where the toxic properties of metals, such as copper, are exploited to aid in microbial clearance. However, previous studies investigating the antimicrobial efficacy of copper in vivo have reported variable findings. Here, we use a highly copper-sensitive strain of S. pneumoniae, lacking both copper efflux and intracellular copper buffering by glutathione, to investigate how copper stress is managed and where it is encountered during infection. We show that this strain exhibits highly dysregulated copper homeostasis, leading to the attenuation of growth and hyperaccumulation of copper in vitro. In a murine infection model, whole-tissue copper quantitation and elemental bioimaging of the murine lung revealed that infection with S. pneumoniae resulted in increased copper abundance in specific tissues, with the formation of spatially discrete copper hot spots throughout the lung. While the increased copper was able to reduce the viability of the highly copper-sensitive strain in a pneumonia model, copper levels in professional phagocytes and in a bacteremic model were insufficient to prosecute bacterial clearance. Collectively, this study reveals that host copper is redistributed to sites of infection and can impact bacterial viability in a hypersusceptible strain. However, in wildtype S. pneumoniae, the concerted actions of the copper homeostatic mechanisms are sufficient to facilitate continued viability and virulence of the pathogen. IMPORTANCE Streptococcus pneumoniae (the pneumococcus) is one of the world’s foremost bacterial pathogens. Treatment of both localized and systemic pneumococcal infection is becoming complicated by increasing rates of multidrug resistance globally. Copper is a potent antimicrobial agent used by the mammalian immune system in the defense against bacterial pathogens. However, unlike other bacterial species, this copper stress is unable to prosecute pneumococcal clearance. This study determines how the mammalian host inflicts copper stress on S. pneumoniae and the bacterial copper tolerance mechanisms that contribute to maintenance of viability and virulence in vitro and in vivo. This work has provided insight into the chemical biology of the hostpneumococcal interaction and identified a potential avenue for novel antimicrobial development.2022-01-01T00:00:00ZCinnamaldehyde derivatives act as antimicrobial agents against Acinetobacter baumannii through the inhibition of cell divisionChai, W.C.Whittall, J.J.Polyak, S.W.Foo, K.Li, X.Dutschke, C.J.Ogunniyi, A.D.Ma, S.Sykes, M.J.Semple, S.J.Venter, H.https://hdl.handle.net/2440/1368332023-11-19T23:39:46Z2022-01-01T00:00:00ZTitle: Cinnamaldehyde derivatives act as antimicrobial agents against Acinetobacter baumannii through the inhibition of cell division
Author: Chai, W.C.; Whittall, J.J.; Polyak, S.W.; Foo, K.; Li, X.; Dutschke, C.J.; Ogunniyi, A.D.; Ma, S.; Sykes, M.J.; Semple, S.J.; Venter, H.
Abstract: Acinetobacter baumannii is a pathogen with high intrinsic antimicrobial resistance while multidrug resistant (MDR) and extensively drug resistant (XDR) strains of this pathogen are emerging. Treatment options for infections by these strains are very limited, hence new therapies are urgently needed. The bacterial cell division protein, FtsZ, is a promising drug target for the development of novel antimicrobial agents. We have previously reported limited activity of cinnamaldehyde analogs against Escherichia coli. In this study, we have determined the antimicrobial activity of six cinnamaldehyde analogs for antimicrobial activity against A. baumannii. Microscopic analysis was performed to determine if the compounds inhibit cell division. The on-target effect of the compounds was assessed by analyzing their effect on polymerization and on the GTPase activity of purified FtsZ from A. baumannii. In silico docking was used to assess the binding of cinnamaldehyde analogs. Finally, in vivo and in vitro safety assays were performed. All six compounds displayed antibacterial activity against the critical priority pathogen A. baumannii, with 4-bromophenyl-substituted 4 displaying the most potent antimicrobial activity (MIC 32 μg/mL). Bioactivity was significantly increased in the presence of an efflux pump inhibitor for A. baumannii ATCC 19606 (up to 32-fold) and significantly, for extensively drug resistant UW 5075 (greater than 4-fold), suggesting that efflux contributes to the intrinsic resistance of A. baumannii against these agents. The compounds inhibited cell division in A. baumannii as observed by the elongated phenotype and targeted the FtsZ protein as seen from the inhibition of polymerization and GTPase activity. In silico docking predicted that the compounds bind in the interdomain cleft adjacent to the H7 core helix. Di-chlorinated 6 was devoid of hemolytic activity and cytotoxicity against mammalian cells in vitro, as well as adverse activity in a Caenorhabditis elegans nematode model in vivo. Together, these findings present halogenated analogs 4 and 6 as promising candidates for further development as antimicrobial agents aimed at combating A. baumannii. This is also the first report of FtsZ-targeting compounds with activity against an XDR A. baumannii strain.
Description: PUBLISHED 29 August 20222022-01-01T00:00:00ZWorldwide distribution and environmental origin of the Adelaide imipenemase (AIM-1), a potent carbapenemase in Pseudomonas aeruginosaAmsalu, A.Sapula, S.A.Whittall, J.J.Hart, B.J.Bell, J.M.Turnidge, J.Venter, H.https://hdl.handle.net/2440/1365302023-11-20T01:05:19Z2021-01-01T00:00:00ZTitle: Worldwide distribution and environmental origin of the Adelaide imipenemase (AIM-1), a potent carbapenemase in Pseudomonas aeruginosa
Author: Amsalu, A.; Sapula, S.A.; Whittall, J.J.; Hart, B.J.; Bell, J.M.; Turnidge, J.; Venter, H.
Abstract: Carbapenems are potent broad-spectrum β-lactam antibiotics reserved for the treatment of serious infections caused by multidrug-resistant bacteria such as Pseudomonas aeruginosa. The surge in P. aeruginosa resistant to carbapenems is an urgent threat, as very few treatment options remain. Resistance to carbapenems is predominantly due to the presence of carbapenemase enzymes. The assessment of 147 P. aeruginosa isolates revealed that 32 isolates were carbapenem non-wild-type. These isolates were screened for carbapenem resistance genes using PCR. One isolate from wastewater contained the Adelaide imipenemase gene (bla AIM-1) and was compared phenotypically with a highly carbapenem-resistant clinical isolate containing the bla AIM-1 gene. A further investigation of wastewater samples from various local healthcare and non-healthcare sources as well as river water, using probe-based qPCR, revealed the presence of the bla AIM-1 gene in all the samples analysed. The widespread occurrence of bla AIM-1 throughout Adelaide hinted at the possibility of more generally extensive spread of this gene than originally thought. A blast search revealed the presence of the bla AIM-1 gene in Asia, North America and Europe. To elucidate the identity of the organism(s) carrying the bla AIM-1 gene, shotgun metagenomic sequencing was conducted on three wastewater samples from different locations. Comparison of these nucleotide sequences with a whole-genome sequence of a P. aeruginosa isolate revealed that, unlike the genetic environment and arrangement in P. aeruginosa, the bla AIM-1 gene was not carried as part of any mobile genetic elements. A phylogenetic tree constructed with the deduced amino acid sequences of AIM-1 suggested that the potential origin of the bla AIM-1 gene in P. aeruginosa might be the non-pathogenic environmental organism, Pseudoxanthomonas mexicana.
Description: Published 17 December 20212021-01-01T00:00:00ZProtein kinase R is an innate immune sensor of proteotoxic stress via accumulation of cytoplasmic IL-24Davidson, S.Yu, C.-H.Steiner, A.Ebstein, F.Baker, P.J.Jarur-Chamy, V.Hrovat Schaale, K.Laohamonthonkul, P.Kong, K.Calleja, D.J.Harapas, C.R.Balka, K.R.Mitchell, J.Jackson, J.T.Geoghegan, N.D.Moghaddas, F.Rogers, K.L.Mayer-Barber, K.D.De Jesus, A.A.De Nardo, D.et al.https://hdl.handle.net/2440/1358642023-11-20T02:21:10Z2022-01-01T00:00:00ZTitle: Protein kinase R is an innate immune sensor of proteotoxic stress via accumulation of cytoplasmic IL-24
Author: Davidson, S.; Yu, C.-H.; Steiner, A.; Ebstein, F.; Baker, P.J.; Jarur-Chamy, V.; Hrovat Schaale, K.; Laohamonthonkul, P.; Kong, K.; Calleja, D.J.; Harapas, C.R.; Balka, K.R.; Mitchell, J.; Jackson, J.T.; Geoghegan, N.D.; Moghaddas, F.; Rogers, K.L.; Mayer-Barber, K.D.; De Jesus, A.A.; De Nardo, D.; et al.
Abstract: Proteasome dysfunction can lead to autoinflammatory disease associated with elevated type I interferon (IFN-αβ) and NF-κB signaling; however, the innate immune pathway driving this is currently unknown. Here, we identified protein kinase R (PKR) as an innate immune sensor for proteotoxic stress. PKR activation was observed in cellular models of decreased proteasome function and in multiple cell types from patients with proteasome-associated autoinflammatory disease (PRAAS). Furthermore, genetic deletion or small-molecule inhibition of PKR in vitro ameliorated inflammation driven by proteasome deficiency. In vivo, proteasome inhibitor-induced inflammatory gene transcription was blunted in PKR-deficient mice compared with littermate controls. PKR also acted as a rheostat for proteotoxic stress by triggering phosphorylation of eIF2α, which can prevent the translation of new proteins to restore homeostasis. Although traditionally known as a sensor of RNA, under conditions of proteasome dysfunction, PKR sensed the cytoplasmic accumulation of a known interactor, interleukin-24 (IL-24). When misfolded IL-24 egress into the cytosol was blocked by inhibition of the endoplasmic reticulum-associated degradation pathway, PKR activation and subsequent inflammatory signaling were blunted. Cytokines such as IL-24 are normally secreted from cells; therefore, cytoplasmic accumulation of IL-24 represents an internal danger-associated molecular pattern. Thus, we have identified a mechanism by which proteotoxic stress is detected, causing inflammation observed in the disease PRAAS.2022-01-01T00:00:00Z