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Sp 22 13330 2017 Skachat Pdf

Naturally occurring β-hydroxy-α-amino acids (βH-AAs) are key residues in many bioactive metabolites, such as glycopeptide antibiotics (Williams 1984), cyclopeptides (Genet 1996) and β-lactone antibiotic obafluorin (Schaffer et al. 2017; Scott et al. 2017). Some of βH-AAs are also specialised metabolites with a range of antimicrobial and anticancer bioactivities. Among these βH-AAs, 4-fluorothreonine 1 is the only fluorinated β-hydroxy-α-amino acid natural product. It is known that fluorinated α-amino acids constitute an important class of compounds due to their unique metabolic and physiological activities. They have been applied as biological tracers, enzyme inhibitors and for medical applications (Salwiczek et al. 2012). Selective fluorination to generate fluorinated amino acids has been well-developed. However, only few reported enzymatic syntheses of fluorinated amino acids. In 2007, Steinreiber et al. examined L-threonine aldolase (L-TA) from Pseudomonas putida and D-threonine aldolase (D-TA) from Alcaligenes xylosoxidans in the biotransformation of generating various 3-alkylserine derivatives. Incubating fluoroacetaldehyde with glycine in the presence of L-TA and PLP gave 4-FT (L-syn-fluorothreonine) with 50% yield, while D-TA was able to generate D-syn-fluorothreonine in the presence of PLP, manganese ion and DTA together with glycine and fluoroacetaldehyde (Steinreiber et al. 2007).

sp 22 13330 2017 skachat pdf

FTase homologous genes have been mainly found in actinomycetes (Mcmurry and Chang 2017). In 2019, a new FTase homologue (GenBank Accession No. VFJ60022) emerged in NCBI from the Gram-negative bacterium, Candidatus Kentron sp. DK, a symbiont of the marine ciliate, Kentrophoros (Seah et al. 2019). However, a comparative genomic and a sequence similarity network analyses using the sequences of FTases, FthB and FthC as sequence queries suggested that neither the flA gene homologue nor fthB and fthC homologous genes were found in close proximity of the flFT opening reading frame (orf) or in the draft genome of Candidatus Kentron sp. DK (Fig. S14). Thus, it is less clear if there is any metabolic significance for this flFT gene or if there is any benefit for the bacterial communities in the corresponding symbiotic host, the marine ciliate Kentrophoros. 041b061a72


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