Soluble in CHCl3, CH2Cl2, dioxane, pyridine, glacial acetic acid, DMF. Practically insoluble in the lower alcohols, nonpolar organic solvents, diluted aqueous acids or bases. May be dissolved by methanolic acid or base, but with decomposition.[2]
Thiostrepton was discovered by Donovick et al. who described its antibacterial properties in 1955.[3]Dorothy Crowfoot Hodgkin solved the structure of thiostrepton in 1970.[4]
Early in 1978, Bycroft and Gowland[5]
proposed the biosynthesis of thiostrepton, which was still unclear until 2009. Several studies of thiopeptide biosynthesis[6][7][8][9] have been contemporarily published in 2009 and two of them (Liao et al. and Kelly et al.) included the similar biosynthesis of thiostrepton: it's ribosomally synthesized from thiostrepton biosynthetic genes (tsr genes) and posttranslational modification is needed.[citation needed]
A total synthesis of thiostrepton was completed by K.C. Nicolaou, et al. in 2004.[10][11]
Applications
Thiostrepton has been used in veterinary medicine in mastitis caused by gram-negative organisms and in dermatologic disorders. It is mostly used in complex ointments containing neomycin, nystatin, Thiostrepton and topical steroids. It is also active against gram-positive bacteria. It is notable that ointments for human usage contain neomycin, nystatin, and topical steroids, but no thiostrepton.[citation needed]
Thiostrepton was reported (in 2008) to exhibit activity against breast cancer cells through targeting the transcription factor forkhead box M1 (FOXM1),[12] also in 2011.[13]
It has also been shown to circumvent acquired cisplatin resistance in breast cancer cells under in vitro conditions.[14]
Thiostrepton is used in molecular biology as a reagent for both positive and negative selection of genes involved in nucleotide metabolism.[citation needed]
Thiostrepton has also shown promise in treating osteoporosis in animal models because it can inhibit unusual osteoclast precursor cells.[15]
The antibiotic thiostrepton was identified as an insulin resistance reversal agent. Subsequent validation in ex vivo insulin-resistant mouse muscle and palmitate-induced insulin-resistant myotubes demonstrated potent insulin action restoration, possibly via upregulation of glycolysis due to attenuation of mitochondrial oxidative phosphorylation by thiostrepton.[16]
Effects of thiostrepton on stringent response
Thiostrepton binds to the L11 protein of the large ribosomal subunit. Mutations in this protein confer resistance to this metabolite.[17] The L11 protein is also essential for regulating the RelA protein [18] and activating the synthesis of the cellular alarmone (p)ppGpp, which, in turn, triggers the stringent response and antibiotic synthesis. Furthermore, amino acid substitutions in the L11 protein that confer resistance to thiostrepton also inhibit the stringent response in strains belonging to the Streptomyces genus.[19] A similar mechanism has been observed in Neisseria gonorrhoeae, where thiostrepton reduces the synthesis of (p)ppGpp, inhibiting the activation of the persistence.[20] Persistence is a mechanism that allows bacteria to survive antibiotic treatments and other stressors by enabling a subpopulation of bacteria to become metabolically inactive.
Biosynthesis
There are total 21 genes (tsrA~tsrU) in the biosynthetic gene cluster. The precursor of thiostrepton contains 58 amino acids in the peptide chain, which includes 41-aa leader peptide (LP) and 17-aa structural peptide (IASASCTTCICTCSCSS). Once the precursor is synthesized, cyclodehydratase tsrO and dehydrogenase tsrM catalyze the formation of thiazole or thiazoline from every cysteine residues in the peptide chain. After thiazole/thiazoline formation, dehydratases tsrJ, K and S then convert all the serine residues into dehydroalanines. A hetero Diels-Alder cyclization of the central dehydropiperidine (at S5, C13, and S14) has been suggested by Bycroft back to 1978 and been employed in the chemical synthesis of this core structure by Nicolaou et al. in 2005. An alternative mechanism of the dehydropiperidine formation has also been suggested by Kelly et al. in 2009. Nevertheless, based on experimental evidence, tsrN and L are suggested to be responsible for the hetero Diels-Alder cyclization. The quinaldic acid moiety is suggested to be synthesized by the nine genes tsrFAEBDUPQI from tryptophan and then results in the closure of quinaldic acid macrocycle. At last, tsrR serves as a candidate for the oxidation of the Ile residue to afford thiostrepton.[citation needed]
Alternative mechanism for the formation of the dehydropiperidine core
Total synthesis
In 2005, Nicolaou et al. published the total synthesis of thiostrepton. At first, they constructed the key building blocks of thiostrepton (1): dehydropiperidine core (2), thiazoline macrocycle (3), bis-dehydroalanine tail (4), and quinaldic acid macrocycle (5). Then they assembled the building blocks sequentially as shown in the synthetic scheme (compound numbers are from the reference).
^Bycroft, Barrie W.; Gowland, Maxim S. (1978). "The structures of the highly modified peptide antibiotics micrococcin P1 and P2". Journal of the Chemical Society, Chemical Communications (6): 256. doi:10.1039/c39780000256. ISSN0022-4936.
^Kelly WL, Pan L, Li C (2009). "Thiostrepton biosynthesis: prototype for a new family of bacteriocins". J. Am. Chem. Soc. 131 (12): 4327–34. doi:10.1021/ja807890a. PMID19265401.
^Nicolaou, K. C.; Zak, Mark; Safina, Brian S.; Estrada, Anthony A.; Lee, Sang Hyup; Nevalainen, Marta (2005). "Total Synthesis of Thiostrepton. Assembly of Key Building Blocks and Completion of the Synthesis". Journal of the American Chemical Society. 127 (31): 11176–11183. doi:10.1021/ja052934z. ISSN0002-7863. PMID16076225.
^Nicolaou KC, Safina BS, Zak M, Lee SH, Nevalainen M, Bella M, Estrada AA, Funke C, Zécri FJ, Bulat S (2005). "Total synthesis of thiostrepton. Retrosynthetic analysis and construction of key building blocks". J. Am. Chem. Soc. 127 (31): 11159–75. doi:10.1021/ja0529337. PMID16076224.
^Kwok JM, Myatt SS, Marson CM, Coombes RC, Constantinidou D, Lam EW (July 2008). "Thiostrepton selectively targets breast cancer cells through inhibition of forkhead box M1 expression". Mol. Cancer Ther. 7 (7): 2022–32. doi:10.1158/1535-7163.MCT-08-0188. PMID18645012. S2CID33941442.
^Masson, S. W., Madsen, S., Cooke, K. C., Potter, M., Vegas, A. D., Carroll, L., ... & James, D. E. (2023). Leveraging genetic diversity to identify small molecules that reverse mouse skeletal muscle insulin resistance. Elife, 12, RP86961 https://doi.org/10.7554/eLife.86961; bioRxiv doi:10.1101/2023.03.01.530673 This article incorporates text from this source, which is available under the CC BY 4.0 license.
