Activities | Families | Sequences | Fold types | References | Help
B6db references: 21884568

type Journal Article
authors Binter A, Oberdorfer G, Hofzumahaus S, Nerstheimer S, Altenbacher G, Gruber K, Macheroux P.
title Characterization of the PLP-dependent aminotransferase NikK from Streptomyces tendae and its putative role in nikkomycin biosynthesis.
journal FEBS J
Activity nikk
Family nikk
sel selected
ui 21884568
year (2011)
volume 278
number 21
pages 4122-35
abstract As inhibitors of chitin synthase, nikkomycins have attracted interest as potential antibiotics. The biosynthetic pathway to these peptide nucleosides in Streptomyces tendae is only partially known. In order to elucidate the last step of the biosynthesis of the aminohexuronic building block, we have heterologously expressed a predicted aminotransferase encoded by the gene nikK from S. tendae in Escherichia coli. The purified protein, which is essential for nikkomycin biosynthesis, has a pyridoxal-5'-phosphate cofactor bound as a Schiff base to lysine 221. The enzyme possesses aminotransferase activity and uses several standard amino acids as amino group donors with a preference for glutamate (Glu > Phe > Trp > Ala > His > Met > Leu). Therefore, we propose that NikK catalyses the introduction of the amino group into the ketohexuronic acid precursor of nikkomycins. At neutral pH, the UV-visible absorbance spectrum of NikK has two absorbance maxima at 357 and 425 nm indicative of the presence of the deprotonated and protonated aldimine with an estimated pK(a) of 8.3. The rate of donor substrate deamination is faster at higher pH, indicating that an alkaline environment favours the deamination reaction.

last changed 2018/03/27 10:14

B6db references