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Biology of Acinetobacter spp.
Published in E. Bergogne-Bénézin, M.L. Joly-Guillou, K.J. Towner, Acinetobacter, 2020
The ability of a bacterium to obtain the necessary iron for growth in the human body is now recognised to be an important virulence determinant, and some strains of Acinetobacter have been shown to produce siderophores and iron-repressible outer-membrane receptor proteins (Smith et al., 1990; Echenique et al., 1992; Actis et al., 1993). These observations may have important implications when attempting to explain the virulence of certain strains, and it is clear that the entire question of uptake of various compounds and molecules into acinetobacters (and related efflux systems) is an important area for further research effort if the physiology and pathogenicity of this genus is to be elucidated adequately.
Metal Ion Dependent Antibiotics in Chemotherapy
Published in Astrid Sigel, Helmut Sigel, Metal Ions in Biological Systems, 2004
David H. Petering, Chuanwu Xia, William E. Antholine
Albomycin, like bacterial siderophores, binds to an outer membrane receptor/transporter (fhuA in E. coli) and is moved into the periplasmic space in an energy dependent process that involves a second protein, TonB [137,138]. There it associates with another protein, fluD [139]. Finally, it moves into the cell through the inner membrane in an ATP-dependent process. Once in the cell, peptidase N hydrolyzes the structure, releasing the active antibiotic moiety [134,139].
Proteus
Published in Dongyou Liu, Laboratory Models for Foodborne Infections, 2017
Paola Scavone, Victoria Iribarnegaray, Pablo Zunino
Iron acquisition systems are an important virulence determinant that enhances bacterial colonization of the host cells and survival in the environment [25]. Iron is an essential micronutrient for all living organisms, and its acquisition is vital for bacteria considering that only a minor fraction is available (10−18 M). In order to capture iron, bacteria have evolved high-affinity iron-scavenging and uptake systems [25]. The main strategies used by bacteria are the production and uptake of siderophores and the direct utilization of host iron compounds such as transferrin, lactoferrin, or heme-containing molecules [25]. Gram-negative Fe(III) acquisition systems usually consist of an outer membrane receptor, with transport across the outer membrane by TonB/ExbB/ExbD complex, a periplasmic binding protein, and an inner membrane ABC transporter. In P. mirabilis, there are at least two gene clusters related to siderophore biosynthesis and ABC transport, three outer membrane proteins induced by iron starvation involved in heme uptake, and a heme receptor [26,27]. One of the clusters related to siderophore biosynthesis is a novel nonribosomal peptide syntheses (NRPS)-independent siderophore (NIS) named proteobactin, as this was first described in a bacterium [28]. The other one contains the nrp operon, which has been previously described to be upregulated during iron limitation [29]. This operon is encoded within the high pathogenicity island (HPI) in P. mirabilis HI4320 that shows homology compared to the HPI of Yersinia spp. [30]. Infection challenges with mutant strains in different genes involved in yersiniabactin-related siderophore showed that it contributes to P. mirabilis fitness in vivo [31].
Growth of Porphyromonas gingivalis on human serum albumin triggers programmed cell death
Published in Journal of Oral Microbiology, 2023
Shirin Ghods, M. Fata Moradali, Danielle Duryea, Alejandro R. Walker, Mary E. Davey
In addition, asRNA corresponding to HmuY showed the lowest relative expression at early lysis phase in strain W83, suggesting that these growth conditions are inducing changes in the levels of HmuY transcript (PG1551) or protein. Although changes in the levels of PG1551 (HmuY) were not detected, other genes in the PG1551 operon (PG1553, PG1555, and PG1556) were found – to be expressed at higher levels (2.8–3.8-fold) in strain W83 when compared to strain W50 during exponential growth. HmuY is an important outer membrane associated heme-binding lipoprotein that plays an essential role in the acquisition of iron, a critical co-factor for electron transport, growth, and virulence [63,64]; hence, our data provided some insight into the role of iron in tolerating envelope stress and suggested iron-acquisition genes as potential targets for drug development. Iron is a key signal for oxidative stress responses and expression of outer membrane proteins in bacteria [65] and hemin are known to protect P. gingivalis from oxidative stress [66]. Previously, it was shown that iron uptake in the cyanobacterium Anabaena sp. PCC 7120 is regulated by a 2,200-nucleotide cis-asRNA via decreasing furA expression and translation [67]. Also, outer membrane receptor for ferrienterochelin and colicins can counteract the production of reactive oxygen species during the general stress response [68,69]. Here, we showed that upon providing a higher concentration of hemin, P. gingivalis can extend long-term survival in stationary phase when grown on HSA.
Cefiderocol: a novel siderophore cephalosporin
Published in Expert Opinion on Investigational Drugs, 2018
Justin J Choi, Matthew W. McCarthy
As we see the use of cefiderocol and other siderophore-based antibiotics increase, we will undoubtedly have to address its resistance mechanisms. An important mechanism of resistance to siderophore-antibiotic conjugates is targeted at specific outer-membrane transporters, thus a better understanding of the structure and function of these outer-membrane receptor proteins will be necessary. The field of proteomics will prove to be a critical area of research, and we will see the development of novel proteomic strategies and technologies that will be employed to provide diagnostic and prognostic information about siderophore-related proteins as it relates drug therapy and resistance.
Non-antibiotic antibacterial peptides and proteins of Escherichia coli: efficacy and potency of bacteriocins
Published in Expert Review of Anti-infective Therapy, 2021
Juraj Bosák, Matěj Hrala, Lenka Micenková, David Šmajs
Colicins have a relatively narrow spectrum of activity and this antimicrobial specificity is determined by the interaction of colicins with outer membrane receptors, which allow subsequent translocation of the colicin molecule to the cellular target. Colicin receptors are primarily involved in the transport of physiological ligands, such as vitamin B12 or siderophores, and are only secondarily parasitized by colicins.