Teicoplanin A2-2 (Tei)/
A40926 is the last-line
antibiotic to treat multidrug-resistant
Gram-positive bacterial infections, e.g., methicillin-resistant Staphylococcus aureus (MRSA) and
vancomycin-resistant enterococcus (VRE). This class of
antibiotics is powered by the N-
acyltransferase (
NAT) Orf11*/Dbv8 through N-acylation on
glucosamine at the central residue of Tei/
A40926 pseudoaglycone. The
NAT enzyme possesses enormous value in untapped applications; its advanced development is hampered largely due to a lack of structural information. In this report, we present eight high-resolution X-ray crystallographic unary, binary, and ternary complexes in order to decipher the molecular basis for
NAT's functionality. The
enzyme undergoes a multistage conformational change upon binding of
acyl-CoA, thus allowing the uploading of Tei pseudoaglycone to enable the acyl-transfer reaction to take place in the occlusion between the N- and C-halves of the
protein. The acyl moiety of
acyl-CoA can be bulky or lengthy, allowing a large extent of diversity in new derivatives that can be formed upon its transfer.
Vancomycin/synthetic acyl-N-acetyl
cysteamine was not expected to be able to serve as a surrogate for an acyl acceptor/donor, respectively. Most strikingly,
NAT can catalyze formation of 2-N,6-O-diacylated or C6→C2 acyl-substituted Tei analogues through an unusual 1,4-migration mechanism under stoichiometric/solvational reaction control, wherein selected representatives showed excellent
biological activities, effectively counteracting major types (VanABC) of VRE.