TY - JOUR
T1 - Characterization of the PLP-dependent aminotransferase NikK from Streptomyces tendae and its putative role in nikkomycin biosynthesis
AU - Binter, Alexandra
AU - Oberdorfer, Gustav
AU - Hofzumahaus, Sebastian
AU - Nerstheimer, Stefanie
AU - Altenbacher, Georg
AU - Gruber, Karl
AU - MacHeroux, Peter
PY - 2011/11/1
Y1 - 2011/11/1
N2 - 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-5â-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. Structured digital abstract to by As inhibitors of chitin synthase, nikkomycins have attracted interest as potential antibiotics. However, information on the biosynthetic reactions leading to these peptide nucleosides is still very limited. In order to elucidate the last step of the biosynthesis of the aminohexuronic building block of nikkomycins, we have identified a pyridoxal-5-phosphate dependent aminotransferase
AB - 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-5â-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. Structured digital abstract to by As inhibitors of chitin synthase, nikkomycins have attracted interest as potential antibiotics. However, information on the biosynthetic reactions leading to these peptide nucleosides is still very limited. In order to elucidate the last step of the biosynthesis of the aminohexuronic building block of nikkomycins, we have identified a pyridoxal-5-phosphate dependent aminotransferase
KW - aminohexuronic acid
KW - antibiotics
KW - docking
KW - homology model
UR - http://www.scopus.com/inward/record.url?scp=80255141922&partnerID=8YFLogxK
U2 - 10.1111/j.1742-4658.2011.08319.x
DO - 10.1111/j.1742-4658.2011.08319.x
M3 - Article
C2 - 21884568
AN - SCOPUS:80255141922
SN - 1742-464X
VL - 278
SP - 4122
EP - 4135
JO - The FEBS Journal
JF - The FEBS Journal
IS - 21
ER -