Abstract
The multinuclear nonheme iron-dependent oxidases (MNIOs) are a rapidly growing family of enzymes involved in the biosynthesis of ribosomally synthesized, posttranslationally modified peptide natural products (RiPPs). Recently, a secreted virulence factor from nontypeable Haemophilus influenzae (NTHi) was found to be expressed from an operon, which we designate the hvf operon, that also encodes an MNIO. Here, we show by Mössbauer spectroscopy that the MNIO HvfB contains a triiron cofactor. We demonstrate that HvfB works together with HvfC [a RiPP recognition element (RRE)-containing partner protein] to perform six posttranslational modifications of cysteine residues on the virulence factor precursor peptide HvfA. Structural characterization by tandem mass spectrometry and NMR shows that these six cysteine residues are converted to oxazolone and thioamide pairs, similar to those found in the RiPP methanobactin. Like methanobactin, the mature virulence factor, which we name oxazolin, uses these modified residues to coordinate Cu(I) ions. Considering the necessity of oxazolin for host cell invasion by NTHi, these findings point to a key role for copper during NTHi infection. Furthermore, oxazolin and its biosynthetic pathway represent a potential therapeutic target for NTHi.
Original language | English (US) |
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Article number | e2408092121 |
Journal | Proceedings of the National Academy of Sciences of the United States of America |
Volume | 121 |
Issue number | 28 |
DOIs | |
State | Published - Jul 9 2024 |
Funding
ACKNOWLEDGMENTS.We would like to thank Yun Ji Park for her contributions to the inception of this project.This work was supported by funding from the following NIH grants: R35 GM118035 (A.C.R.), F32 AI176709 (O.M.M.), T32 GM140995 (T.J.S.), R35 GM143054 (J.J.Z.), R01 GM125924 (Y.G.), and P41 GM108569 and R01 AT009143 (N.L.K.). We would like to acknowledge Fernando Tobias, Saman Shafie, and Yongbo Zhang of Northwestern Integrated Molecular Structure Education and Research Center (IMSERC) for assistance with MS and NMR data collection.IMSERC is supported by Northwestern University and the State of Illinois.
Keywords
- RiPP natural product
- metalloenzyme
- nonheme iron
- virulence factor
ASJC Scopus subject areas
- General