Download MendeleyStructure-Based Mechanistic Insights into ColB1, a Flavoprotein Functioning in-trans in the 2,2'-Bipyridine Assembly Line for Cysteine Dehydrogenation.
Ma, X., Tang, Z., Ding, W., Liu, T., Yang, D., Liu, W., Ma, M.(2023) ACS Chem Biol 18: 18-24
- PubMed: 36603145
- DOI: https://doi.org/10.1021/acschembio.2c00785
- Primary Citation of Related Structures:
7XP7 - PubMed Abstract:
The recruitment of trans -acting enzymes by nonribosomal peptide synthetase (NRPS) assembly line is rarely reported. ColB1 is a flavin-dependent dehydrogenase that is recruited by an NRPS terminal condensation domain (Ct domain) and catalyzes peptidyl carrier protein (PCP)-tethered cysteine dehydrogenation in collismycin biosynthesis. We here report the crystal structure of ColB1 complexed with FAD and reveal a typical structural fold of acyl-CoA dehydrogenases (ACADs). However, ColB1 shows distinct structural features from ACADs in substrate recognition both at the entrance of and inside the active site. Site-directed mutagenesis and substrate modeling establish a Glu393-mediated catalytic mechanism, by which the cysteine substrate is sandwiched between Glu393 and FAD to facilitate C α proton abstraction and C β hydride migration. A ColB1-PCP-Ct complex model is generated, providing structural basis for the unique recruitment interactions between ColB1 and the associated NRPS. These results add insights into the mechanisms by which trans -acting enzymes function in an assembly line.
Organizational Affiliation:
State Key Laboratory of Natural and Biomimetic Drugs, Department of Natural Medicines, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Haidian District, Beijing 100191, China.
