Browsing by Author "Wang, S."
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Aminoacyl chain translocation catalysed by a type II thioesterase domain in an unusual non-ribosomal peptide synthetase(NATURE COMMUNICATIONS, 2022) Wang, S.; Brittain, W.D.G.; Zhang, Q.; Lu, Z.; Tong, M.H.; Wu, K.; Kyeremeh, K.; Jenner, M.; Yu, Y.; Cobb, S.L.; Deng, H.Non-Ribosomal Peptide Synthetases (NRPSs) assemble a diverse range of natural products with important applications in both medicine and agriculture. They consist of several multienzyme subunits that must interact with each other in a highly controlled manner to facilitate efficient chain transfer, thus ensuring biosynthetic fidelity. Several mechanisms for chain transfer are known for NRPSs, promoting structural diversity. Herein, we report the first biochemically characterized example of a type II thioesterase (TEII) domain capable of catalysing aminoacyl chain transfer between thiolation (T) domains on two separate NRPS subunits responsible for installation of a dehydrobutyrine moiety. Biochemical dissection of this process reveals the central role of the TEII-catalysed chain translocation event and expands the enzymatic scope of TEII domains beyond canonical (amino)acyl chain hydrolysis. The apparent co-evolution of the TEII domain with the NRPS subunits highlights a unique feature of this enzymatic cassette, which will undoubtedly find utility in biosynthetic engineering efforts.Item Genomic scanning enabling discovery of a new antibacterial bicyclic carbamate-containing alkaloid(Synthetic and Systems Biotechnology, 2021) Fang, Q.; Wu, L.; Urwald, C.; Mugat, M.; Wang, S.; Kyeremeh, K.; Philips, C.; Law, S.; Zhou, Y.; Deng, H.Non-ribosomal peptides are a group of structurally diverse natural products with various important therapeutic and agrochemical applications. Bacterial pyrrolizidine alkaloids (PAs), containing a scaffold of two fused fivemembered ring system with a nitrogen atom at the bridgehead, have been found to originate from a multidomain non-ribosomal peptide synthetase to generate indolizidine intermediates, followed by multistep oxidation, catalysed by single Bayer-Villiger (BV) enzymes, to yield PA scaffolds. Although bacterial PAs are rare in natural product inventory, bioinformatics analysis suggested that the biosynthetic gene clusters (BGCs) that are likely to be responsible for the production of PA-like metabolites are widely distributed in bacterial genomes. However, most of the strains containing PA-like BGCs are not deposited in the public domain, therefore preventing further assessment of the chemical spaces of this group of bioactive metabolites. Here, we report a genomic scanning strategy to assess the potential of PA metabolites production in our culture collection without prior knowledge of genome information. Among the strains tested, we found fifteen contain the key BV enzymes that are likely to be involved in the last step of PA ring formation. Subsequently one-strain-many-compound (OSMAC) method, supported by a combination of HR-MS, NMR, SMART 2.0 technology, and GNPS analysis, allowed identification and characterization of a new [5 + 7] heterobicyclic carbamate, legoncarbamate, together with five known PAs, bohemamine derivatives, from Streptomyces sp. CT37, a Ghanaian soil isolate. The absolute stereochemistry of legoncarbamate was determined by comparison of measured and calculated ECD spectra. Legoncarbamate displays antibacterial activity against E. coli ATCC 25922 with an MIC value of 3.1 μg/mL. Finally, a biosynthetic model of legoncarbamate and other bohemamines was proposed based on the knowledge we have gained so far.Item Presentation and survival of multiple myeloma patients in Ghana: a review of 169 cases(Ghana medical journal, 2019-03) Dei-Adomakoh, Y.; Acquah, M.E.; Hsing, A.W.; McGuire, V.; Wang, S.; Birmann, B.Background: Africans have an increased risk for multiple myeloma (MM) compared to other races. Reports from Africa are few and involve small cohorts, but suggest significant epidemiological and clinical differences from Caucasian patients. Objective: This report describes the clinic-pathological features of MM patients in Ghana at diagnosis, and the factors affecting their survival. Methods: A retrospective review of 169 MM cases diagnosed in a Ghanaian tertiary hospital from 2002-2016. Results: Median age was 58 years, with 29% ≤50 years. One-third presented >12 months after onset of symptoms, which included bone pain (96%), anaemia (67%), weight loss (55%) and fractures (44%). Myeloma-related tissue impairment included hypercalcaemia (36%), renal impairment (33%), severe anaemia (52%) and osteolytic lesions (76%); 51.3% of patients were diagnosed in ISS Stage III. Median survival was 33 months; 1-year and 5-year overall survival were 51.6% and 15.5%, respectively. Neither the age at diagnosis nor the duration of symptoms prior to diagnosis correlated with prognosis. Median survival improved with early ISS stage, haemoglobin >8g/dL, plasmacytosis <20%, and normal creatinine and calcium levels. Conclusion: Early onset and late stage presentation are common at diagnosis of MM patients in Ghana, but do not affect survival. Studies into genetic associations are recommended.Item An unusual metal-bound 4-fluorothreonine transaldolase from Streptomyces sp. MA37 catalyses promiscuous transaldol reactions(Applied Microbiology and Biotechnology, 2020-03-06) Kyeremeh, K.; Wu, L.; Tong, M.H.; Raab, A.; Fang, Q.; Wang, S.; Yu, Y.; Deng, H.β-Hydroxy-α-amino acids (βH-AAs) are key components of many bioactive molecules as well as exist as specialised metabolites. Among these βH-AAs, 4-fluorothreonine (4-FT) is the only naturally occurring fluorinated AA discovered thus far. Here we report overexpression and biochemical characterisation of 4-fluorothreonine transaldolase from Streptomyces sp. MA37 (FTaseMA), a homologue of FTase previously identified in the biosynthesis of 4-FT in S. cattleya. FTaseMA displays considerable substrate plasticity to generate 4-FT as well as other β-hydroxy-α-amino acids with various functionalities at C4 position, giving the prospect of new chemo-enzymatic applications. The enzyme has a hybrid of two catalytic domains, serine hydroxymethyltransferase (S) and aldolase (A). Site-directed mutagenesis allowed the identification of the key residues of FTases, suggesting that the active site of A domain has a historical reminiscent feature in metal-dependent aldolases. Elemental analysis demonstrated that FTaseMA is indeed a Zn2+-dependent enzyme, the first example of pyridoxal phosphate (PLP) enzyme family fused with a metal-binding domain carrying out a distinct catalytic role. Finally, FTaseMA showed divergent evolutionary origin with other PLP dependent enzymes