The Origins of Specificity in the Microcin-Processing Protease TldD/E.Ghilarov, D., Serebryakova, M., Stevenson, C.E.M., Hearnshaw, S.J., Volkov, D.S., Maxwell, A., Lawson, D.M., Severinov, K.
(2017) Structure 25: 1549-1561.e5
- PubMed: 28943336
- DOI: https://doi.org/10.1016/j.str.2017.08.006
- Primary Citation of Related Structures:
5NJ5, 5NJ9, 5NJA, 5NJB, 5NJC, 5NJF
- PubMed Abstract:
TldD and TldE proteins are involved in the biosynthesis of microcin B17 (MccB17), an Escherichia coli thiazole/oxazole-modified peptide toxin targeting DNA gyrase. Using a combination of biochemical and crystallographic methods we show that E. coli TldD and TldE interact to form a heterodimeric metalloprotease. TldD/E cleaves the N-terminal leader sequence from the modified MccB17 precursor peptide, to yield mature antibiotic, while it has no effect on the unmodified peptide. Both proteins are essential for the activity; however, only the TldD subunit forms a novel metal-containing active site within the hollow core of the heterodimer. Peptide substrates are bound in a sequence-independent manner through β sheet interactions with TldD and are likely cleaved via a thermolysin-type mechanism. We suggest that TldD/E acts as a "molecular pencil sharpener": unfolded polypeptides are fed through a narrow channel into the active site and processively truncated through the cleavage of short peptides from the N-terminal end.
Centre for Data-Intensive Biomedicine and Biotechnology, Skolkovo Institute of Science and Technology, 143026 Moscow, Russia; Bionano Institute, Peter the Great Saint Petersburg State Polytechnical University, Saint Petersburg 195251, Russia; Waksman Institute for Microbiology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA. Electronic address: firstname.lastname@example.org.