Structure of Chlamydomonas reinhardtii THB1

Experimental Data Snapshot

  • Resolution: 1.89 Å
  • R-Value Free: 0.217 
  • R-Value Work: 0.187 
  • R-Value Observed: 0.188 

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This is version 1.4 of the entry. See complete history


Structure of Chlamydomonas reinhardtii THB1, a group 1 truncated hemoglobin with a rare histidine-lysine heme ligation.

Rice, S.L.Boucher, L.E.Schlessman, J.L.Preimesberger, M.R.Bosch, J.Lecomte, J.T.

(2015) Acta Crystallogr F Struct Biol Commun 71: 718-725

  • DOI: https://doi.org/10.1107/S2053230X15006949
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    THB1 is one of several group 1 truncated hemoglobins (TrHb1s) encoded in the genome of the unicellular green alga Chlamydomonas reinhardtii. THB1 expression is under the control of NIT2, the master regulator of nitrate assimilation, which also controls the expression of the only nitrate reductase in the cell, NIT1. In vitro and physiological evidence suggests that THB1 converts the nitric oxide generated by NIT1 into nitrate. To aid in the elucidation of the function and mechanism of THB1, the structure of the protein was solved in the ferric state. THB1 resembles other TrHb1s, but also exhibits distinct features associated with the coordination of the heme iron by a histidine (proximal) and a lysine (distal). The new structure illustrates the versatility of the TrHb1 fold, suggests factors that stabilize the axial ligation of a lysine, and highlights the difficulty of predicting the identity of the distal ligand, if any, in this group of proteins.

  • Organizational Affiliation

    Chemistry Department, US Naval Academy, 572 Holloway Road, Annapolis, MD 21402, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Chlamydomonas reinhardtii THB1
A, B
135Chlamydomonas reinhardtiiMutation(s): 0 
Gene Names: THB1CHLREDRAFT_81856CHLRE_14g615400v5
Find proteins for A8JAR4 (Chlamydomonas reinhardtii)
Explore A8JAR4 
Go to UniProtKB:  A8JAR4
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA8JAR4
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on HEM

Download Ideal Coordinates CCD File 
C [auth A],
D [auth B]
C34 H32 Fe N4 O4
Experimental Data & Validation

Experimental Data

  • Resolution: 1.89 Å
  • R-Value Free: 0.217 
  • R-Value Work: 0.187 
  • R-Value Observed: 0.188 
  • Space Group: P 61 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 144.513α = 90
b = 144.513β = 90
c = 79.913γ = 120
Software Package:
Software NamePurpose
XDSdata scaling
CrysalisProdata scaling
XSCALEdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
National Science Foundation (NSF, United States)United StatesMCB-1330488

Revision History  (Full details and data files)

  • Version 1.0: 2015-01-21
    Type: Initial release
  • Version 1.1: 2015-07-15
    Changes: Database references
  • Version 1.2: 2016-07-20
    Changes: Data collection
  • Version 1.3: 2017-09-20
    Changes: Author supporting evidence, Derived calculations, Refinement description
  • Version 1.4: 2019-11-27
    Changes: Author supporting evidence