Interdomain and Intermodule Organization in Epimerization Domain Containing Nonribosomal Peptide Synthetases

Area of Science:

• Biochemistry
• Structural Biology
• Enzymology

Background:

• Nonribosomal peptide synthetases (NRPSs) are large enzymes synthesizing diverse peptidic natural products.
• NRPS chemistry relies on thioester intermediates, protein interactions, and interdomain dynamics.
• Incorporation of d-amino acids is crucial for the bioactivity of many nonribosomal peptides.

Purpose of the Study:

• To elucidate the structure of the epimerization domain/peptidyl carrier protein didomain from gramicidin synthetase.
• To understand the structural basis for l- to d-amino acid conversion within NRPS assembly lines.
• To gain insights into domain-domain recognition and substrate delivery in NRPS.

Main Methods:

• X-ray crystallography was used to determine the structures of the epimerization domain/peptidyl carrier protein didomain construct.
• Both holo (post-translationally modified) and apo forms of the didomain were analyzed.
• Structural analysis focused on catalytically relevant conformations.

Main Results:

• The structures of both holo and apo forms of the epimerization domain/peptidyl carrier protein didomain were determined.
• The determined structures represent catalytically relevant conformations.
• Insights into domain-domain recognition and substrate delivery mechanisms were obtained.

Conclusions:

• The determined structures provide crucial insights into the mechanism of epimerization within NRPS.
• Understanding these structures aids in comprehending the assembly line process of NRPS.
• This work contributes to the structural understanding of homologous condensation domains in NRPS.