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Genetically Modified Salmonella as Cancer Therapeutics: Mechanisms, Advances, and Challenges
Published in Ananda M. Chakrabarty, Arsénio M. Fialho, Microbial Infections and Cancer Therapy, 2019
However, the mutants were randomly introduced and other genes in the strain might be affected coincidentally. Katherine and colleagues found that VNP20009 bred additional deletions, which might impair its antitumor capacity in vivo [40]. For example, there is a single nucleotide polymorphism in the chemotaxis gene cheY of VNP20009. VNP20009 is therefore impaired in flagella synthesis and becomes nonchemotactic. With the availability of entire bacterial genome sequences and rapid development of technics, Salmonella can now easily be manipulated at genetic levels. Our lab engineered a Salmonella mutant by deleting phoP and phoQ by the RED recombinase method to enable the mutant to release a shRNA-expressing plasmid [50]. The mutant exhibited a better safety profile than VNP20009. In addition, Salmonella deleting znuABC or aroA also displayed promising anticancer effects [51].
Proteus
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
María José González, Pablo Zunino, Paola Scavone
Iron acquisition systems are important virulence factors that enhance bacterial colonization of the host cells and survival in the environment. In order to capture the iron in the environment, bacteria have multiple strategies, including the production and uptake of siderophores and the direct utilization of host iron compounds such as lactoferrin, transferring, or heme-containing molecules [51]. In P. mirabilis there are at least two gene clusters related to siderophore biosynthesis, three outer membrane proteins induced by iron starvation, and a heme receptor [52,53]. The siderophores present in P. mirabilis are related to a novel nonribosomal peptide synthase (NRPS)-independent siderophore named proteobactin and to a high pathogenicity island (HPI) that shows homology with the HPI of Yersinia spp. named yersiniabactin [54–56]. P. mirabilis also has other strategies to obtain other biologically important elements needed for bacterial growth, like zinc and phosphate. Zinc is utilized by the P. mirabilis ZnuABC high-affinity transport system [41]. Also, it possesses the high-affinity phosphate transporter system Pst. It is postulated that this system is important in P. mirabilis virulence, being involved in biofilm formation [57].
Exosomes: from biology to immunotherapy in infectious diseases
Published in Infectious Diseases, 2023
Velia Verónica Rangel-Ramírez, Hilda Minerva González-Sánchez, César Lucio-García
Outer-membrane vesicles can also aid in bacterial survival under stress conditions and nutrient acquisition. They can provide envelope stress relief through the disposal of misfolded proteins, peptidoglycan fragments, or lipopolysaccharide [318–320]. Moreover, vesiculation increases during oxidative stress [318–321]. Furthermore, these vesicles are also proposed to have a role in bacterial community formation and provide nutrients during colonization. For example, the outer-membrane vesicles from Borrelia burgdorferi contain enolase which is essential to bacterial glycolysis and may contribute to colonization [17,218]. Several bacterial species release outer-membrane vesicles containing iron acquisition proteins and receptors for haem groups, such as FetA and FetB47 (iron transporter components) present in the vesicles of N. meningitidis [272]; IhtB, HmuY and gingipains released by Porphyromonas gingivalis [278]; as well as CopB, the haem chaperone CcmE and the surface receptor transferrin-binding protein B from Moraxella catarrhalis [322–324]. In addition, the zinc acquisition proteins ZnuA and ZnuD47 have also been detected in the outer-membrane vesicles of N. meningitidis showing that metal acquisition through these vesicles is not only restricted to iron [272].
Alkyl rhamnosides, a series of amphiphilic materials exerting broad-spectrum anti-biofilm activity against pathogenic bacteria via multiple mechanisms
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Guanghua Peng, Xucheng Hou, Wenxi Zhang, Maoyuan Song, Mengya Yin, Jiaxing Wang, Jiajia Li, Yajie Liu, Yuanyuan Zhang, Wenkai Zhou, Xinru Li, Guiling Li
The suppression of ABC transporters was another mechanism of anti-biofilm by 12C-Rha since nine proteins (OpuC, CycB, PstC, PhnC, ZnuA, MtsA, MtsB, HrtA and BraD) mapped to ABC transporters were downregulated. Thus, related substrates such as osmoprotectant, arabinogalactan oligomer/maltooligosaccharide, phosphate, phosphonate, iron/zinc/manganese/copper, hemin and bacitracin could not be transported properly in biofilm cells, causing the disruption of S. aureus biofilms [28]. Moreover, the function of ZnuA and MtsA that is directly related with iron transportation should be emphasized because iron is important for biofilm development [29]. Lack of iron might lead to the deficiency and disruption of biofilm [30].
Microbial adaptation to the healthy and inflamed gut environments
Published in Gut Microbes, 2020
Yijie Guo, Sho Kitamoto, Nobuhiko Kamada
Inflammation-driven functional reprograming is crucial for allowing pathogens to gain the edge in the inflamed gut. As shown in Figure 2d, Salmonella-induced colitis increases the luminal concentration of total bile acid. To resist the elevated bile concentration during colitis, S. enterica ser. Typhimurium modifies its outer membranes (i.e., very long O-antigen chains) through regulation of FepE.59 This enables S. enterica ser. Typhimurium to adapt better to the inflamed gut than commensal bacteria, which are susceptible to bile salts. Also, S. enterica ser. Typhimurium expresses genes that are required to tolerate the host antimicrobial responses. Salmonella-induced colitis releases calprotectin, an antimicrobial protein secreted from dead neutrophils in the intestinal lumen, which can inhibit bacterial growth by sequestering essential micronutrient metals (e.g., zinc). S. enterica ser. Typhimurium expresses a high-affinity zinc transporter (ZnuABC) in the inflamed gut.60 ZnuABC gives S. enterica ser. Typhimurium a significant fitness advantage over commensal bacteria by overcoming calprotectin-mediated zinc chelation Figure 2d. Likewise, S. enterica ser. Typhimurium upregulates the transcription of l-lactate utilization genes to use lactate in the gut lumen as an electron donor.52S. enterica ser. Typhimurium and AIEC increase transcription of the eut operon to use intestinal ethanolamine, which is secreted from intestinal epithelial cells during inflammation.61,62 This selective use of ethanolamine gives the pathogens a competitive edge over commensal bacteria. As discussed earlier, iron is of critical importance to pathogen fitness in several species of Proteobacteria (e.g., E. coli). Iron metabolism is vital for efficient bacterial colonization and presentation in the gut and proliferation in the disseminated bloodstream.63–66 During intestinal inflammation, AIEC overexpress the genes encoding propanediol utilization (pdu operon) and iron acquisition (yersiniabactin, chu operon), thereby promoting intestinal inflammation.37 Also, it has been shown that enterobactin, a catecholate siderophore secreted by E. coli, dampens the activity of myeloperoxidase released from neutrophils in the inflamed gut, thus giving the growth advantage to E. coli over other commensals.67 Kitamoto et al. found that pathogenic Enterobacteriaceae, such as AIEC LF82 and C. rodentium, shift their metabolism from carbohydrate to amino acid catabolism in the inflamed gut.68 In particular, l-serine catabolism is vital for the competitive fitness of these pathogens over commensal bacteria. Intriguingly, l-serine catabolism does not control the fitness of these pathogens in the absence of inflammation, suggesting that l-serine–dependent growth is a selective strategy used by pathogenic Enterobacteriaceae during inflammation Figure 2d.