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Chloramphenicol
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
Chloramphenicol is a broad-spectrum antibiotic of the amphenicol class with primarily bacteriostatic activity, that was first isolated from cultures of Streptomyces venezuelae in 1947, but is now produced synthetically. It is effective against a wide variety of microorganisms, but due to serious adverse effects (e.g. damage to the bone marrow, including aplastic anemia) in humans, it is usually reserved for the treatment of serious and life-threatening infections. It is used for typhoid fever and for the treatment of cholera, as it destroys the vibrios and decreases the diarrhea. Chloramphenicol is mostly used in skin ointments, ear drops for the treatment of otitis externa and eye drops or ointment to treat bacterial conjunctivitis (1). Chloramphenicol was first reported as a contact sensitizer in 1951 (44).
The Americas
Published in Michael J. O’Dowd, The History of Medications for Women, 2020
In 1949 Mildred C. Rebstock, of the Parke-Davis Company in Detroit, was the first to synthesize chloramphenicol (Duin and SutclifFe, 1992). The antibiotic was isolated from soil samples containing Streptomyces venezuelae, an organism first found two years previously by Burkholder in soil samples collected in Venezuela.
C
Published in Anton Sebastian, A Dictionary of the History of Medicine, 2018
Chloromycetin Chloramphenicol was prepared from Streptomyces venezuelae from soil by John Ehrlich (b 1907), P.R. Burkholder and co-workers in 1947. Its effectiveness against rickettsial infections was demonstrated by Joseph Edwin Smadel (1907–1963) and Elizabeth B.Jackson in 1948.
MlrA, a MerR family regulator in Vibrio cholerae, senses the anaerobic signal in the small intestine of the host to promote bacterial intestinal colonization
Published in Gut Microbes, 2022
Jialin Wu, Yutao Liu, Wendi Li, Fan Li, Ruiying Liu, Hao Sun, Jingliang Qin, Xiaohui Feng, Di Huang, Bin Liu
Unlike most MerR family regulators, a unique binding site for MlrA was identified by us from −234 to −217 bp from the translational start site of tcpA. We also showed that, unlike most MerR family regulators, MlrA cannot bind to the – 35 and – 10 elements of the promoter region of the gene (tcpA) that it regulates. To date, very few MerR family regulators have been shown to bind to parts of the DNA region other than the – 35 and – 10 elements. For example, MlrA in E. coli directly binds to – 146 to – 133 bp segment from the csgD translational start site with a palindromic sequence of AAAATTGTACA(12 N)TGTACAATTTT.45 In addition, MerR-like protein BldC in Streptomyces venezuelae binds to the −50 to −80 bp segment from the translational start site of whiI, which plays a critical role in Streptomyces differentiation.35 Although these two binding sites do not share obvious sequence homology with that of MlrA in V. cholerae, all three binding sites contain a conserved AATT motif. It is likely that this AATT motif act as an essential domain for DNA-protein interactions of MerR family regulators.
Repositioning rifamycins for Mycobacterium abscessus lung disease
Published in Expert Opinion on Drug Discovery, 2019
Uday S. Ganapathy, Véronique Dartois, Thomas Dick
As oxidizing conditions in the cytosol of M. tuberculosis and M. abscessus are likely to be similar, autoxidation cannot explain the differential potency of rifampicin in these species. Rather, M. abscessus may express antibiotic-degrading enzymes that can take advantage of the oxidizable hydroquinone chemistry of rifamycins. M. abscessus encodes putative FAD-monooxygenases [57], a class of enzymes that confer drug resistance by oxidizing rifamycins. Notably, the Rox monooxygenases of Streptomyces venezuelae and Nocardia farcinica conferred resistance to rifampicin and rifapentine, but not rifabutin [61], as these enzymes can only oxidize rifamycins with a susceptible hydroquinone. It is not known if M. abscessus similarly utilizes enzyme-mediated oxidation to resist rifamycins, but rifabutin would be able to avoid such a resistance mechanism (Figure 1).
Improving the attrition rate of Lanthipeptide discovery for commercial applications
Published in Expert Opinion on Drug Discovery, 2018
Mining for lanthipeptide synthetase also led to the discovery of the first type IV lanthipeptide venezuelin (Figure 3(d)) [27]. By analyzing the genome sequence of Streptomyces venezuelae, the authors noticed a gene venL encoding a putative lanthipeptide synthetase. However, the N-terminal region encodes an S/T kinase instead of the dehydratase domain present in LanM, and its C-terminal encodes a LanC-like cyclase domain. The dehydration and cyclization function of VenL was verified by comparing putative bacteriocin structural gene venA with the product after expressing both VenL and VenA in E. coli. Due to the presence of all 12 conserved subdomains of protein S/T kinases in the central part of LanL, which are absent in LanB and LanM proteins, venezuelin was classified as a new class of lanthipeptide, termed as type IV lanthipeptide.