4AAO

MacA-H93G


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.190 

wwPDB Validation 3D Report Full Report


This is version 1.0 of the entry. See complete history

Literature

Maca is a Second Cytochrome C Peroxidase of Geobacter Sulfurreducens.

Seidel, J.Hoffmann, M.Ellis, K.E.Seidel, A.Spatzal, T.Gerhardt, S.Elliott, S.J.Einsle, O.

(2012) Biochemistry 51: 2747

  • DOI: 10.1021/bi300249u
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The metal-reducing δ-proteobacterium Geobacter sulfurreducens produces a large number of c-type cytochromes, many of which have been implicated in the transfer of electrons to insoluble metal oxides. Among these, the dihemic MacA was assigned a centr ...

    The metal-reducing δ-proteobacterium Geobacter sulfurreducens produces a large number of c-type cytochromes, many of which have been implicated in the transfer of electrons to insoluble metal oxides. Among these, the dihemic MacA was assigned a central role. Here we have produced G. sulfurreducens MacA by recombinant expression in Escherichia coli and have solved its three-dimensional structure in three different oxidation states. Sequence comparisons group MacA into the family of diheme cytochrome c peroxidases, and the protein indeed showed hydrogen peroxide reductase activity with ABTS(-2) as an electron donor. The observed K(M) was 38.5 ± 3.7 μM H(2)O(2) and v(max) was 0.78 ± 0.03 μmol of H(2)O(2)·min(-1)·mg(-1), resulting in a turnover number k(cat) = 0.46 · s(-1). In contrast, no Fe(III) reductase activity was observed. MacA was found to display electrochemical properties similar to other bacterial diheme peroxidases, in addition to the ability to electrochemically mediate electron transfer to the soluble cytochrome PpcA. Differences in activity between CcpA and MacA can be rationalized with structural variations in one of the three loop regions, loop 2, that undergoes conformational changes during reductive activation of the enzyme. This loop is adjacent to the active site heme and forms an open loop structure rather than a more rigid helix as in CcpA. For the activation of the protein, the loop has to displace the distal ligand to the active site heme, H93, in loop 1. A H93G variant showed an unexpected formation of a helix in loop 2 and disorder in loop 1, while a M297H variant that altered the properties of the electron transfer heme abolished reductive activation.


    Organizational Affiliation

    Lehrstuhl für Biochemie, Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104 Freiburg, Germany.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CYTOCHROME C551 PEROXIDASE
A, B
341Geobacter sulfurreducens (strain ATCC 51573 / DSM 12127 / PCA)Mutation(s): 1 
Gene Names: macA
Find proteins for Q74FY6 (Geobacter sulfurreducens (strain ATCC 51573 / DSM 12127 / PCA))
Go to UniProtKB:  Q74FY6
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A, B
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
CA
Query on CA

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

Download SDF File 
Download CCD File 
A, B
HEME C
C34 H34 Fe N4 O4
HXQIYSLZKNYNMH-LJNAALQVSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.190 
  • Space Group: P 65 2 2
Unit Cell:
Length (Å)Angle (°)
a = 118.719α = 90.00
b = 118.719β = 90.00
c = 245.980γ = 120.00
Software Package:
Software NamePurpose
REFMACrefinement
iMOSFLMdata reduction
MOLREPphasing
SCALAdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2011-12-05 
  • Released Date: 2012-10-17 
  • Deposition Author(s): Seidel, J.

Revision History 

  • Version 1.0: 2012-10-17
    Type: Initial release