2BUE

Structure of AAC(6')-Ib in complex with Ribostamycin and Coenzyme A.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.211 
  • R-Value Work: 0.182 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Mechanistic and Structural Analysis of Aminoglycoside N-Acetyltransferase Aac(6')-Ib and its Bifunctional, Fluoroquinolone-Active Aac(6')-Ib-Cr Variant.

Vetting, M.W.Park, C.H.Hegde, S.S.Jacoby, G.A.Hooper, D.C.Blanchard, J.S.

(2008) Biochemistry 47: 9825

  • DOI: 10.1021/bi800664x
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Enzymatic modification of aminoglycoside antibiotics mediated by regioselective aminoglycoside N-acetyltransferases is the predominant cause of bacterial resistance to aminoglycosides. A recently discovered bifunctional aminoglycoside acetyltransfera ...

    Enzymatic modification of aminoglycoside antibiotics mediated by regioselective aminoglycoside N-acetyltransferases is the predominant cause of bacterial resistance to aminoglycosides. A recently discovered bifunctional aminoglycoside acetyltransferase (AAC(6')-Ib variant, AAC(6')-Ib-cr) has been shown to catalyze the acetylation of fluoroquinolones as well as aminoglycosides. We have expressed and purified AAC(6')-Ib-wt and its bifunctional variant AAC(6')-Ib-cr in Escherichia coli and characterized their kinetic and chemical mechanism. Initial velocity and dead-end inhibition studies support an ordered sequential mechanism for the enzyme(s). The three-dimensional structure of AAC(6')-Ib-wt was determined in various complexes with donor and acceptor ligands to resolutions greater than 2.2 A. Observation of the direct, and optimally positioned, interaction between the 6'-NH 2 and Asp115 suggests that Asp115 acts as a general base to accept a proton in the reaction. The structure of AAC(6')-Ib-wt permits the construction of a molecular model of the interactions of fluoroquinolones with the AAC(6')-Ib-cr variant. The model suggests that a major contribution to the fluoroquinolone acetylation activity comes from the Asp179Tyr mutation, where Tyr179 makes pi-stacking interactions with the quinolone ring facilitating quinolone binding. The model also suggests that fluoroquinolones and aminoglycosides have different binding modes. On the basis of kinetic properties, the pH dependence of the kinetic parameters, and structural information, we propose an acid/base-assisted reaction catalyzed by AAC(6')-Ib-wt and the AAC(6')-Ib-cr variant involving a ternary complex.


    Organizational Affiliation

    Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
AAC(6')-IB
A
202Escherichia coliMutation(s): 2 
Gene Names: AAC(6')-Ib (aac(6')-Ib-cr, aac(6`)-Ib-cr, aacA-aphD, aacA-aphD_1, aacA4)
Find proteins for Q6SJ71 (Escherichia coli)
Go to UniProtKB:  Q6SJ71
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download SDF File 
Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
COA
Query on COA

Download SDF File 
Download CCD File 
A
COENZYME A
C21 H36 N7 O16 P3 S
RGJOEKWQDUBAIZ-IBOSZNHHSA-N
 Ligand Interaction
RIO
Query on RIO

Download SDF File 
Download CCD File 
A
RIBOSTAMYCIN
5-AMINO-2-AMINOMETHYL-6-[4,6-DIAMINO-2-(3,4-DIHYDROXY-5-HYDROXYMETHYL-TETRAHYDRO-FURAN-2-YLOXY)-3-HYDROXY-CYCLOHEXYLOXY]-TETRAHYDRO-PYRAN-3,4-DIOL; (1R,2R,3S,4R,6S)-4,6-diamino-3-hydroxy-2-(beta-D-ribofuranosyloxy)cyclohexyl 2,6-diamino-2,6-dideoxy-alpha-D-glucopyranoside
C17 H34 N4 O10
NSKGQURZWSPSBC-VVPCINPTSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.211 
  • R-Value Work: 0.182 
  • Space Group: P 43 21 2
Unit Cell:
Length (Å)Angle (°)
a = 57.475α = 90.00
b = 57.475β = 90.00
c = 148.305γ = 90.00
Software Package:
Software NamePurpose
MOSFLMdata reduction
REFMACrefinement
SCALAdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2008-09-02
    Type: Initial release
  • Version 1.1: 2011-05-08
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance