11TU | pdb_000011tu

Crystal structure of alpha/beta-hydrolase macrolide esterase EstT from Bacillus cereus (S102A mutant) in complex with linearized tylvalosin

PDB DOI: https://doi.org/10.2210/pdb11TU/pdb

Classification: HYDROLASE
Organism(s): Bacillus cereus
Expression System: Escherichia coli BL21
Mutation(s): Yes

Deposited: 2026-03-12 Released: 2026-04-08
Deposition Author(s): Kelly, E.T.R., Blanchet, J., Berghuis, A.M.
Funding Organization(s): Canadian Institutes of Health Research (CIHR)

Experimental Data Snapshot

Method: X-RAY DIFFRACTION
Resolution: 1.70 Å
R-Value Free:
0.201 (Depositor), 0.201 (DCC)
R-Value Work:
0.178 (Depositor), 0.178 (DCC)
R-Value Observed:
0.179 (Depositor)

Starting Model: in silico
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wwPDB Validation 3D Report Full Report

Ligand Structure Quality Assessment

This is version 1.1 of the entry. See complete history.

Literature

Hydration and hydrolysis define antibiotic resistance conferred by macrolide esterases.

Kelly, E.T.R., Myziuk, I., Hemmings, M.Z., Mulla, Z., Blanchet, J., Ruzzini, A., Berghuis, A.M.

(2026) Proc Natl Acad Sci U S A 123: e2611077123-e2611077123

PubMed: 42455676 Search on PubMed Search on PubMed Central
DOI: https://doi.org/10.1073/pnas.2611077123
Primary Citation Related Structures:
11TS, 11TT, 11TU, 11TV, 11TW

PubMed Abstract:
Macrolides are an antibiotic class widely used in both human and veterinary medicine, and function by interfering with protein synthesis. Regrettably, numerous strategies for evading the antibiotic properties of macrolides have been found in bacteria, including enzyme-mediated inactivation. These mechanisms are now widely disseminated among pathogenic, animal-associated, and environmental bacteria making them a One Health issue. Macrolide esterases, which hydrolyze the macrolactone's ester bond, confer one such resistance mechanism. Two types of macrolide esterases have thus far been identified, the well-studied erythromycin esterases and the recently discovered Est-type enzymes that belong to the α/β-hydrolase superfamily. We present detailed structure-function studies for four diverse Est type esterases: which only share 44 to 66% sequence identity (EstT _Sf, EstT _St, EstT _Bc, and EstX _Ec). In addition to resistance profiling and substrate specificity studies, we present structures for all four enzymes, including structures for EstT _Bc and EstX _Ec in complex with tylosin and tylvalosin macrolides, posthydrolysis. Complementing the data with mutational and kinetic studies allowed for a detailed analysis of the structural basis for macrolide-enzyme interactions. Combined, the data suggest that promiscuous binding and imprecise positioning, mediated by a water-cage, dictate substrate specificity for Est-type macrolide resistance enzymes. These insights may prove beneficial for next-generation antibiotic development.

Organizational Affiliation

Department of Biochemistry, McGill University, Montréal, QC H3A 1A3, Canada.

Macromolecule Content

Total Structure Weight: 32.57 kDa
Atom Count: 2,356
Modeled Residue Count: 270
Deposited Residue Count: 284
Unique protein chains: 1

Macromolecules

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| 3D Structure

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
alpha/beta-hydrolase macrolide esterase EstT	A	284	Bacillus cereus	Mutation(s): 1 Gene Names: CN307_07515
Entity Groups
Sequence Clusters	30% Identity 50% Identity 70% Identity 90% Identity 95% Identity 100% Identity
Sequence Annotations Expand
Reference Sequence

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram	3D Interactions
A1DAR (Subject of Investigation/LOI) Query on A1DAR Download:Ideal Coordinates CCD File SDF format, chain B [auth A] MOL2 format, chain B [auth A] mmCIF format, chain B [auth A]	B [auth A]	linearized tylvalosin C₅₃ H₉₃ N O₂₀ WXLGBWASBIONQW-NJIHMORWSA-N		Interactions Focus chain B [auth A] Interactions & Density Focus chain B [auth A]