Affordable Access

deepdyve-link
Publisher Website

Distinctive structural properties of THB11, a pentacoordinate Chlamydomonas reinhardtii truncated hemoglobin with N- and C-terminal extensions

Authors
  • Huwald, Dennis1, 2
  • Duda, Sabrina1
  • Gasper, Raphael1, 3
  • Olieric, Vincent4
  • Hofmann, Eckhard1
  • Hemschemeier, Anja1
  • 1 Ruhr University Bochum,
  • 2 Present Address: Charles River Laboratories,
  • 3 Present Address: Max Planck Institute of Molecular Physiology,
  • 4 Swiss Light Source (SLS), Paul-Scherrer-Institute (PSI),
Type
Published Article
Journal
JBIC Journal of Biological Inorganic Chemistry
Publisher
Springer-Verlag
Publication Date
Feb 11, 2020
Volume
25
Issue
2
Pages
267–283
Identifiers
DOI: 10.1007/s00775-020-01759-2
PMID: 32048044
PMCID: PMC7082302
Source
PubMed Central
Keywords
License
Unknown

Abstract

Hemoglobins (Hbs) utilize heme b as a cofactor and are found in all kingdoms of life. The current knowledge reveals an enormous variability of Hb primary sequences, resulting in topological, biochemical and physiological individuality. As Hbs appear to modulate their reactivities through specific combinations of structural features, predicting the characteristics of a given Hb is still hardly possible. The unicellular green alga Chlamydomonas reinhardtii contains 12 genes encoding diverse Hbs of the truncated lineage, several of which possess extended N- or C-termini of unknown function. Studies on some of the Chlamydomonas Hbs revealed yet unpredictable structural and biochemical variations, which, along with a different expression of their genes, suggest diverse physiological roles. Chlamydomonas thus represents a promising system to analyze the diversification of Hb structure, biochemistry and physiology. Here, we report the crystal structure, resolved to 1.75 Å, of the heme-binding domain of cyanomet THB11 (Cre16.g662750), one of the pentacoordinate algal Hbs, which offer a free Fe-coordination site in the reduced state. The overall fold of THB11 is conserved, but individual features such as a kink in helix E, a tilted heme plane and a clustering of methionine residues at a putative tunnel exit appear to be unique. Both N- and C-termini promote the formation of oligomer mixtures, and the absence of the C terminus results in reduced nitrite reduction rates. This work widens the structural and biochemical knowledge on the 2/2Hb family and suggests that the N- and C-terminal extensions of the Chlamydomonas 2/2Hbs modulate their reactivity by intermolecular interactions. Electronic supplementary material The online version of this article (10.1007/s00775-020-01759-2) contains supplementary material, which is available to authorized users.

Report this publication

Statistics

Seen <100 times