Professor Junji Sakamoto of Kyushu Institute of Technology and colleagues have elucidated the precise three-dimensional structure of "cytochrome bd-type respiratory enzyme" that works in Escherichia coli.
"Respiratory enzymes" exist in the cells of animals and microorganisms and work to extract the energy required for life activities from the nutrients of food.Oxygen taken in by breathing oxidizes sugars and lipids to obtain energy.There are "heme copper type" possessed by humans and animals and "cytochrome bd type" peculiar to microorganisms, and research on heme copper type has been progressing for a long time, while research on bd type is in progress.
Previously, Professor Sakamoto et al. Elucidated the precise three-dimensional structure of bd-type respiratory enzymes for the first time in the world in research on thermophiles.This time, we conducted research on the bd-type respiratory enzyme of Escherichia coli, and succeeded in clarifying the second precise three-dimensional structure using cryo-electron microscopy (cryo-electron microscopy), which has made remarkable progress in recent years.
Although classified in the same bd type, there were far more differences than previously expected between thermophile respiratory enzymes and Escherichia coli respiratory enzymes.In addition to structural differences such as the reversal of the arrangement of heme b and heme d, and the different paths of oxygen in the enzyme molecule, the enzyme of thermophilic bacteria has the main function of detoxifying "oxygen toxicity". On the other hand, it was found that the enzyme of Escherichia coli mainly plays an important role in energy acquisition, and the diversity of bd-type respiratory enzyme was clarified.
Thermophiles are classified as "gram-positive bacteria" and Escherichia coli is classified as "gram-negative bacteria".It can be said that this result has clarified the range of diversity by aligning the three-dimensional structures of respiratory enzymes in two groups of academically important microorganisms.
The bd-type respiratory enzyme is involved in the survival and proliferation of many microorganisms including pathogens such as Mycobacterium tuberculosis and diphtheria.Based on the structural information clarified in this study, it is expected that a new antibacterial drug can be developed by designing a drug that inhibits the bd-type respiratory enzyme of the pathogenic bacterium but does not inhibit the human heme copper-type respiratory enzyme. ..
Paper information:[Science] Active site rearrangement and structural divergence in prokaryotic respiratory oxidases
