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Structure and Evolution of the Small Blue Proteins
Published in René Lontie, Copper Proteins and Copper Enzymes, 1984
The bacterial species mentioned fall in a rather close group. Pseudomonas, Alcaligenes, and Bordetella are found in the Pseudomonaceae, a family of free-living Gram-negative aerobic bacteria. Paracoccus belongs to the Enterobacteriaceae, but resembles several species of the genera Alcaligenes and Pseudomonas, the main difference being the coccoid shape during exponential growth and the absence of flagellation.18Paracoccus denitrificans and some species of Thiobacillus, in particular the denitrifying strains, are in turn quite similar and were earlier confused.19 Doudoroff20 summarizes the situation: “On many grounds, it seems likely that the genera Paracoccus, Pseudomonas, and Alcaligenes are very closely related to each other and that at least the facultatively organotrophic species of the genus Thiobacillus belong in the same generic cluster.”
Cytochrome c Oxidase
Published in René Lontie, Copper Proteins and Copper Enzymes, 1984
Several reports deal with terminal oxidases, including aa3-type cytochromes found in aerobic bacteria.19 The investigation of these enzymes with respect to the now widely accepted theory that mitochondria originated from aerobic bacteria21,175 is one of the most fascinating aspects of a forthcoming understanding of the eukaryotic respiratory functions, the development of the eukaryotic cell, and higher organisms, in general; it was the capability of O2 reduction which provided a means for the upcoming of metazoa.176 The bacterial enzyme which most resembles eukaryotic oxidases has been isolated from Paracoccus denitrificans by Ludwig and Schatz.20 This organism possesses a respiratory chain with characteristics similar to those known in mitochondria.177 Its terminal oxidase contains two heme a and two copper atoms in a functional unit of Mr 73,000 (Table 2) consisting of two subunits with apparent Mr of 45,000 and 28,000, respectively, which resemble the Mr of mitochondrially made subunits I and II (or III) of the eukaryotic oxidases. The enzyme is of the aa3 type, while most of the other bacterial terminal oxidases are not, and has spectral properties similar to those found in the eukaryotic enzyme. The isolated enzyme preserved the redox activity and showed the ability to pump protons.
Gut microbial profiling as a therapeutic and diagnostic target for managing primary biliary cholangitis.
Published in Expert Opinion on Orphan Drugs, 2020
Annarosa Floreani, Sara De Martin, Tsukasa Ikeura, Kazuichi Okazaki, Merrill Eric Gershwin
Several microbial antigens, mainly bacteria, but also viruses, parasites, and fungi have been postulated as possible triggers of PBC [7]. A linear conformational mimicry between microbial proteins and human mitochondrial antigens has been demonstrated for Escherichia coli, Novosphingobium aromaticivorans, Salmonella Minnesota, Pseudomonas aeruginosa, Hemophilus influenzae, Yersinia enterocolitica, Streptococcus intermedius, Lactobacillus delbrueckii, Paracoccus denitrificans, Mycoplam, Mycobacterium gordonae, Borrelia burgdorferi, Trypanosoma, and Ascaridia galli [8]. Interestingly, the infection of genetically susceptible mouse strains with Novosphingobium aromaticivorans induced anti- mitochondrial Pyruvate Dehydrogenase Complex E2 (PDC E2) responses and liver lesions resembling PBC in humans [9]. Moreover, it has been found that IgG3 antibodies directed against b-galactosidase of Lactobacillus delbrueckii cross-react with the same major mitochondrial autoepitope and are characteristic of PBC [10].
Gut bacterial extracellular vesicles: important players in regulating intestinal microenvironment
Published in Gut Microbes, 2022
Xiao Liang, Nini Dai, Kangliang Sheng, Hengqian Lu, Jingmin Wang, Liping Chen, Yongzhong Wang
Besides PQS system, three other QS systems for bacteria-bacteria communication have been discovered: the LuxI/LuxR type among gram-negative bacteria,77 the oligopeptide-two-component type among gram-positive bacteria,78 and the autoinducer 2 (AI-2) type among both gram-negative and gram-positive bacteria.79 Each of these QS systems has its own unique regulatory mechanism. In the LuxI/LuxR QS system, acyl-homoserine lactone (AHL) serves as a signal that can only be recognized by related species. In the oligopeptide-two-component QS system, for signaling, autoinducer peptides must be delivered by a dedicated oligopeptide transporter, which is usually an ABC transporter. In the AI-2 QS system, AI-2 is predominantly mediates interspecific communication.80 Detection of QS molecules in the host is difficult due to the high volatility and dynamics of QS molecules in the complex intestinal environment. To the best of our knowledge, the phenomena of intestinal bacteria using GBEVs to deliver the three aforementioned QS molecules has not been reported in the literature. Morinaga et al. found that BEVs released by Paracoccus denitrificans, a gram-negative, inactive spherical soil bacterium, were able to take up long-chain AHLs secreted by other bacteria from the environment and use it as a signal to control biofilm formation and cell aggregation. This allows P. denitrificans to rapidly reach QS threshold concentrations in complex microbial communities with relatively low populations of their own.81 In summary, QS molecules can regulate population behavior through their enrichment by BEVs, rather than using the classical diffusion pathway. Therefore, we hypothesize that the use of GBEVs carrying specific QS molecules can regulate bacterial population behavior more precisely. Currently, an important topic in clinical research is the treatment of pathogenic bacterial infections using QS system interfering agents, such as meta-bromo-thiolactone82 (inhibits the production of virulence factor pyocyanin and biofilm formation) and cladodionen (inhibits the production of elastase and rhamnolipid, biofilm formation and diffusion, and down-regulates QS-related mRNA expression).83 In addition, competitive inhibition of GBEVs carrying pathogenic QS molecules using engineered GBEVs or influencing the formation of GBEVs through interventions (such as the use of bicyclic compounds including 4-hydroxyindole, isatin, 1-naphthol and 8-quinolinol to significantly inhibit the production of P. aeruginosa EVs and the synthesis of PQS84) are both potential new strategies for the treatment of pathogenic bacteria.