Related Experiment Video

Updated: Mar 21, 2026

Antibiotic Dereplication Using the Antibiotic Resistance Platform
10:49

Antibiotic Dereplication Using the Antibiotic Resistance Platform

Published on: October 17, 2019

11.8K

Antibiotic Binding Drives Catalytic Activation of Aminoglycoside Kinase APH(2″)-Ia

Shane J Caldwell1, Yue Huang1, Albert M Berghuis2

  • 1Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada; Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC H3G 0B1, Canada.

Structure (London, England : 1993)
|May 11, 2016
PubMed

Insights

Aminoglycoside resistance enzyme APH(2″)-Ia uses a novel triphosphate switch mechanism. This switch activates the enzyme only when aminoglycosides bind, preventing wasteful GTP hydrolysis and conferring an evolutionary advantage.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Structural Biology

Background:

  • The enzyme aminoglycoside phosphotransferase (APH(2″)-Ia) is a common resistance factor in Staphylococcus aureus and enterococci.
  • APH(2″)-Ia confers resistance to gentamicin and related aminoglycosides by phosphorylating them.
  • This phosphorylation requires guanosine triphosphate (GTP) as a phosphate donor.

Purpose of the Study:

  • To elucidate the structural mechanism of APH(2″)-Ia-mediated aminoglycoside resistance.
  • To understand how GTP binding and aminoglycoside interaction regulate enzyme activity.

Main Methods:

  • X-ray crystallography was used to determine the structures of APH(2″)-Ia.
  • Structures were obtained for complexes with GTP analogs, guanosine diphosphate, and various aminoglycosides.

Main Results:

  • Aminoglycoside binding induces conformational changes in APH(2″)-Ia, bringing distant protein regions together.
  • These conformational changes facilitate a switch in GTP cofactor from an inactive to an active conformation.
  • This catalytic triphosphate switch mechanism is novel for antibiotic kinases and related eukaryotic kinases.

Conclusions:

  • The APH(2″)-Ia enzyme utilizes a unique catalytic triphosphate switch activated by aminoglycoside binding.
  • This mechanism conserves GTP by preventing hydrolysis when the antibiotic is absent.
  • The switch provides a significant evolutionary advantage to bacteria expressing this resistance factor.

More Related Videos

Author Spotlight: Advancing Antibiotic Resistance Research Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System05:06

Author Spotlight: Advancing Antibiotic Resistance Research Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System

Published on: January 5, 2024

1.2K
Nanomechanics of Drug-target Interactions and Antibacterial Resistance Detection11:56

Nanomechanics of Drug-target Interactions and Antibacterial Resistance Detection

Published on: October 25, 2013

14.8K

Related Concept Videos

Inhibitors of Bacterial Protein Synthesis01:25

Inhibitors of Bacterial Protein Synthesis

Aminoglycosides constitute a highly potent class of bactericidal antibiotics that exert their antimicrobial effects by targeting the bacterial ribosome, specifically disrupting protein synthesis. These polycationic molecules consist of amino-modified sugars linked via glycosidic bonds to an aminocyclitol core such as 2-deoxystreptamine or streptamine. Their strong positive charges facilitate tight binding to the negatively charged phosphate backbone of ribosomal RNA (rRNA), primarily at the 16S...
17
Inhibitors of Gram-positive Cell Wall Synthesis01:23

Inhibitors of Gram-positive Cell Wall Synthesis

Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...
14
Allosteric Proteins-ATCase01:19

Allosteric Proteins-ATCase

Binding sites linkages can regulate a protein's function.  For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to  N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis...
6.9K
Estimation of k and VD of Aminoglycosides01:20

Estimation of k and VD of Aminoglycosides

Aminoglycosides are a class of antibiotics used to treat various bacterial infections. Clinicians must determine the elimination rate constant (k) and volume of distribution (VD) to optimize therapeutic efficacy and minimize toxicity. The k value represents the rate at which the drug is removed from the body, and the VD reflects the degree to which the drug distributes into body tissues. Accurately estimating these parameters allows healthcare professionals to tailor drug dosing to individual...
296
Mechanism of Antibiotic Resistance in MRSA01:25

Mechanism of Antibiotic Resistance in MRSA

Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and...
44
Antifungal Agents01:15

Antifungal Agents

Amphotericin B is a broad-spectrum antifungal agent that exploits structural differences between fungal and mammalian cell membranes. Its amphipathic structure—featuring a hydrophobic polyene-lactone ring and a hydrophilic region containing mycosamine and carboxylic acid groups—enables selective binding to ergosterol, a sterol predominantly found in fungal plasma membranes. This selective interaction underlies the drug’s antifungal activity, although weak binding to...
20