EMD-51976
Pooled 50S subunit C-CP_(L22)- precursor states supplemented with Api137
EMD-51976
Single-particle4.26 Å
Deposition: 01/11/2024
Map released: 29/01/2025
Last modified: 29/01/2025
Sample Organism:
Escherichia coli,
Apis mellifera
Sample: Pooled pre50S substates derived from Api137-treated cells supplemented with Api137 - truncated model with invariant parts between substates
Fitted models: 9ha4
Deposition Authors: Lauer S, Nikolay R, Spahn CMT
Sample: Pooled pre50S substates derived from Api137-treated cells supplemented with Api137 - truncated model with invariant parts between substates
Fitted models: 9ha4
Deposition Authors: Lauer S, Nikolay R, Spahn CMT
The proline-rich antimicrobial peptide Api137 disrupts large ribosomal subunit assembly and induces misfolding.
Lauer SM,
Gasse J,
Krizsan A,
Reepmeyer M,
Sprink T,
Nikolay R,
Spahn CMT,
Hoffmann R
(2025) Nat Commun , 16 , 567
(2025) Nat Commun , 16 , 567
Abstract:
The proline-rich antimicrobial designer peptide Api137 inhibits protein expression in bacteria by binding simultaneously to the ribosomal polypeptide exit tunnel and the release factor (RF), depleting the cellular RF pool and leading to ribosomal arrest at stop codons. This study investigates the additional effect of Api137 on the assembly of ribosomes using an Escherichia coli reporter strain expressing one ribosomal protein per 30S and 50S subunit tagged with mCherry and EGFP, respectively. Separation of cellular extracts derived from cells exposed to Api137 in a sucrose gradient reveals elevated levels of partially assembled and not fully matured precursors of the 50S subunit (pre-50S). High-resolution structures obtained by cryogenic electron microscopy demonstrate that a large proportion of pre-50S states are missing up to five proteins (uL22, bL32, uL29, bL23, and uL16) and have misfolded helices in 23S rRNA domain IV. These data suggest a second mechanism for Api137, wherein it disrupts 50S subunit assembly by inducing the formation of misfolded precursor particles potentially incapable of evolving into active ribosomes, suggesting a bactericidal mechanism.
The proline-rich antimicrobial designer peptide Api137 inhibits protein expression in bacteria by binding simultaneously to the ribosomal polypeptide exit tunnel and the release factor (RF), depleting the cellular RF pool and leading to ribosomal arrest at stop codons. This study investigates the additional effect of Api137 on the assembly of ribosomes using an Escherichia coli reporter strain expressing one ribosomal protein per 30S and 50S subunit tagged with mCherry and EGFP, respectively. Separation of cellular extracts derived from cells exposed to Api137 in a sucrose gradient reveals elevated levels of partially assembled and not fully matured precursors of the 50S subunit (pre-50S). High-resolution structures obtained by cryogenic electron microscopy demonstrate that a large proportion of pre-50S states are missing up to five proteins (uL22, bL32, uL29, bL23, and uL16) and have misfolded helices in 23S rRNA domain IV. These data suggest a second mechanism for Api137, wherein it disrupts 50S subunit assembly by inducing the formation of misfolded precursor particles potentially incapable of evolving into active ribosomes, suggesting a bactericidal mechanism.