9AV9 image
Entry Detail
PDB ID:
9AV9
Title:
R2-state HbG-Makassar hemoglobin
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2024-03-01
Release Date:
2024-12-11
Method Details:
Experimental Method:
Resolution:
1.94 Å
R-Value Free:
0.22
R-Value Work:
0.19
R-Value Observed:
0.19
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Hemoglobin subunit alpha
Chain IDs:A, C
Chain Length:141
Number of Molecules:2
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Hemoglobin subunit beta
Mutations:E6A
Chain IDs:B, D
Chain Length:146
Number of Molecules:2
Biological Source:Homo sapiens
Primary Citation
Base editing HbS to HbG-Makassar improves hemoglobin function supporting its use in sickle cell disease.
Nat Commun 16 1441 1441 (2025)
PMID: 39920120 DOI: 10.1038/s41467-025-56578-3

Abstact

Adenine base editing can convert sickle hemoglobin (HbS, βΕ6V) to G-Makassar hemoglobin (HbG, βE6A), a naturally occurring variant that is clinically asymptomatic. However, the quality and functionality of purified HbG and of mature HbGG and HbGS red blood cells (RBC) has not been assessed. Here, we develop a mouse model to characterize HbG. Purified HbG appears normal and does not polymerize under hypoxia. The topology of the hemoglobin fold with the βΕ6Α mutation is similar to HbA in the oxy and deoxy states. However, RBC containing HbGS are dehydrated, showing altered function and increased sickling under hypoxia. Blood counts and mitochondrial retention measures place HbGS RBCs as intermediate in severity between HbAS and HbSS, while organ function is comparable to HbAS. HbGG resembles HbAA for most metrics. Our results highlight the importance of functionally assessing the mature red cell environment when evaluating novel gene editing strategies for hematologic disorders.

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Primary Citation of related structures