Primary sequence of a dimeric bacterial haemoglobin from Vitreoscilla

Area of Science:

• Microbiology
• Biochemistry
• Molecular Biology

Background:

• Vitreoscilla, a filamentous bacterium, synthesizes a soluble hemeprotein.
• This hemeprotein is produced in large quantities under hypoxic conditions.
• Its oxygenated form is spectrally similar to myoglobin and hemoglobin.

Purpose of the Study:

• To determine the amino acid sequence of the Vitreoscilla hemeprotein.
• To investigate its structural relationship to eukaryotic globins.
• To explore its potential function in oxygen-limited environments.

Main Methods:

• Amino acid sequencing of the Vitreoscilla hemeprotein.
• Sequence alignment with eukaryotic globins.
• Spectral analysis of the oxygenated form.

Main Results:

• The Vitreoscilla hemeprotein is composed of two identical subunits with two b hemes.
• Its amino acid sequence shows homology to eukaryotic globins, suggesting a structural homologue.
• Maximum sequence homology (24%) was observed with lupin leghaemoglobin.
• The protein may lack an A-helix and shows divergence in the N-terminal region.

Conclusions:

• Vitreoscilla hemoglobin is the first bacterial hemoglobin to be sequenced.
• It represents a structural homologue of eukaryotic hemoglobins.
• Potential functions include oxygen storage or facilitating oxygen diffusion in hypoxic conditions.