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Measurement of Heme Synthesis Levels in Mammalian Cells
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Heme Pocket Structure and Its Functional Implications in an Ancestral Globin Protein
Yu Iritani1, Haruto Ishikawa1, Misao Mizuno1
1Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
Biochemistry
|August 30, 2023
Summary
Researchers reconstructed an ancestral protein, AncMH, the common ancestor of hemoglobins and myoglobins. AncMH binds oxygen with its heme group, revealing insights into the evolution of protein stability and function.
Area of Science:
- Biochemistry
- Evolutionary Biology
- Structural Biology
Background:
- Proteins evolve for enhanced stability, functionality, and novel functions.
- Comparative analysis of extant and ancestral proteins illuminates factors driving protein evolution.
- Ancestral sequence reconstruction is a key method for deducing ancient protein sequences.
Purpose of the Study:
- To characterize the structure and function of AncMH, the reconstructed last common ancestor of hemoglobins and myoglobins.
- To understand the evolutionary trajectory of heme-binding proteins.
Main Methods:
- Ancestral sequence reconstruction to generate AncMH.
- Structural and functional assays to characterize AncMH's heme-binding and oxygen interaction.
- Comparative analysis of AncMH's heme pocket with extant hemoglobins and myoglobins.
Main Results:
- AncMH successfully harbors and binds oxygen to its heme group.
- The ferrous heme in AncMH exhibits pentacoordination, akin to human adult hemoglobin and horse myoglobin.
- AncMH's heme pocket structure more closely resembles that of hemoglobin than myoglobin.
- AncMH displays a faster autoxidation rate compared to both hemoglobin and myoglobin.
Conclusions:
- The evolution of hemoglobins and myoglobins occurred stepwise.
- Key evolutionary transitions include the shift from hexa- to pentacoordination and subsequent stabilization of the oxygen-bound form.
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