Journal
ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY
Volume 70, Issue -, Pages 1411-1418Publisher
INT UNION CRYSTALLOGRAPHY
DOI: 10.1107/S1399004714004878
Keywords
-
Funding
- Royal Society [RG110485]
Ask authors/readers for more resources
Plant nonsymbiotic haemoglobins fall into three classes, each with distinct properties but all with largely unresolved physiological functions. Here, the first crystal structure of a class 3 nonsymbiotic plant haemoglobin, that from Arabidopsis thaliana, is reported to 1.77 angstrom resolution. The protein forms a homodimer, with each monomer containing a two-over-two beta-helical domain similar to that observed in bacterial truncated haemoglobins. A novel N-terminal extension comprising two beta-helices plays a major role in the dimer interface, which occupies the periphery of the dimer-dimer face, surrounding an open central cavity. The haem pocket contains a proximal histidine ligand and an open sixth iron-coordination site with potential for a ligand, in this structure hydroxide, to form hydrogen bonds to a tyrosine or a tryptophan residue. The haem pocket appears to be unusually open to the external environment, with another cavity spanning the entrance of the two haem pockets. The final 23 residues of the C-terminal domain are disordered in the structure; however, these domains in the functional dimer are adjacent and include the only two cysteine residues in the protein sequence. It is likely that these residues form disulfide bonds in vitro and it is conceivable that this C-terminal region may act in a putative complex with a partner molecule in vivo.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available