Structural investigations of the hemoglobin of the cyanobacterium Synechocystis PCC6803 reveal a unique distal heme pocket

Manon Couture, Tapan Kanti Das, Pierre Yves Savard, Yannick Ouellet, Jonathan B. Wittenberg, Beatrice A. Wittenberg, Denis L. Rousseau, Michel Guertin

Research output: Contribution to journalArticle

90 Citations (Scopus)

Abstract

A putative hemoglobin (Hb) gene, related to those previously characterized in the green alga Chlamydomonas eugametos, the ciliated protozoan Paramecium caudatum, the cyanobacterium Nostoc commune and the bacterium Mycobacterium tuberculosis, was recently discovered in the complete genome sequence of the cyanobacterium Synechocystis PCC 6803. In this paper, we report the purification of Synechocystis Hb and describe some of its salient biochemical and spectroscopic properties. We show that the recombinant protein contains Fe-protoporphyrin IX and forms a very stable complex with oxygen. The oxygen dissociation rate measured, 0.011 s-1, is among the smallest known and is four orders of magnitude smaller than the rate measured for N. commune Hb, which suggests functional differences between these Hbs. Optical and resonance Raman spectroscopic study of the structure of the heme pocket of Synechocystis Hb reveals that the heme is 6-coordinate and low-spin in both ferric and ferrous forms in the pH range 5.5-10.5. We present evidence that His46, predicted to occupy the helical position E10 based on amino-acid sequence comparison, is involved in the formation of the ferric and ferrous 6-coordinate low-spin structures. The analysis of the His46Ala mutant shows that the ferrous form is 5-coordinate and high-spin and the ferric form contains a 6-coordinate high-spin component in which the sixth ligand is most probably a water molecule. We conclude that the heme pocket of the wild type Synechocystis Hb has a unique structure that requires a histidine residue at the E10 position for the formation of its native structure.

Original languageEnglish (US)
Pages (from-to)4770-4780
Number of pages11
JournalEuropean Journal of Biochemistry
Volume267
Issue number15
DOIs
StatePublished - 2000

Fingerprint

Synechocystis
Cyanobacteria
Heme
Hemoglobins
Nostoc commune
Paramecium caudatum
Genes
Oxygen
Chlamydomonas
Chlorophyta
Algae
Mycobacterium tuberculosis
Recombinant Proteins
Histidine
Purification
Amino Acid Sequence
Bacteria
Genome
Ligands
Amino Acids

Keywords

  • Hemeprotein
  • Non-vertebrate Hb
  • Oxygen-binding
  • Resonance Raman

ASJC Scopus subject areas

  • Biochemistry

Cite this

Couture, M., Das, T. K., Savard, P. Y., Ouellet, Y., Wittenberg, J. B., Wittenberg, B. A., ... Guertin, M. (2000). Structural investigations of the hemoglobin of the cyanobacterium Synechocystis PCC6803 reveal a unique distal heme pocket. European Journal of Biochemistry, 267(15), 4770-4780. https://doi.org/10.1046/j.1432-1327.2000.01531.x

Structural investigations of the hemoglobin of the cyanobacterium Synechocystis PCC6803 reveal a unique distal heme pocket. / Couture, Manon; Das, Tapan Kanti; Savard, Pierre Yves; Ouellet, Yannick; Wittenberg, Jonathan B.; Wittenberg, Beatrice A.; Rousseau, Denis L.; Guertin, Michel.

In: European Journal of Biochemistry, Vol. 267, No. 15, 2000, p. 4770-4780.

Research output: Contribution to journalArticle

Couture, Manon ; Das, Tapan Kanti ; Savard, Pierre Yves ; Ouellet, Yannick ; Wittenberg, Jonathan B. ; Wittenberg, Beatrice A. ; Rousseau, Denis L. ; Guertin, Michel. / Structural investigations of the hemoglobin of the cyanobacterium Synechocystis PCC6803 reveal a unique distal heme pocket. In: European Journal of Biochemistry. 2000 ; Vol. 267, No. 15. pp. 4770-4780.
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