TY - JOUR
T1 - Fluorescence assay of the interaction between hemoglobin and the cytoplasmic domain of erythrocyte membrane band 3
AU - Sega, Martiana F.
AU - Chu, Haiyan
AU - Christian, John A.
AU - Low, Philip S.
N1 - Funding Information:
This work was supported by National Institutes of Health grant GM24417-33 .
Publisher Copyright:
© 2015 Elsevier Inc..
PY - 2015/10/1
Y1 - 2015/10/1
N2 - Oxygen tension has emerged as a potent regulator of multiple erythrocyte properties, including glucose metabolism, cell volume, ATP release, and cytoskeletal organization. Because hemoglobin (Hb)1 binds to the cytoplasmic domain of band 3 (cdb3) in an oxygen dependent manner, with deoxyHb exhibiting significantly greater affinity for cdb3 than oxyHb, the deoxyHb-cdb3 interaction has been hypothesized to constitute the molecular switch for all O2-controlled erythrocyte processes. In this study, we describe a rapid and accurate method for quantitating the interaction of deoxyHb binding to cdb3. For this purpose, enhanced green fluorescent protein (eGFP) is fused to the COOH-terminus of cdb3, and the binding of Hb to the NH2-terminus of cdb3-eGFP is quantitated by Hb-mediated quenching of cdb3-eGFP fluorescence. As expected, the intensity of cdb3-eGFP fluorescence decreases only slightly following addition of oxyHb. However, upon deoxygenation of the same Hb-cdb3 solution, the fluorescence decreases dramatically (i.e. confirming that deoxyHb exhibits much greater affinity for cdb3 than oxyHb). Using this fluorescence quenching method, we not only confirm previously established characteristics of the Hb-cdb3 interaction, but also establish an assay that can be exploited to screen for inhibitors of the sickle Hb-cdb3 interaction that accelerates sickle Hb polymerization.
AB - Oxygen tension has emerged as a potent regulator of multiple erythrocyte properties, including glucose metabolism, cell volume, ATP release, and cytoskeletal organization. Because hemoglobin (Hb)1 binds to the cytoplasmic domain of band 3 (cdb3) in an oxygen dependent manner, with deoxyHb exhibiting significantly greater affinity for cdb3 than oxyHb, the deoxyHb-cdb3 interaction has been hypothesized to constitute the molecular switch for all O2-controlled erythrocyte processes. In this study, we describe a rapid and accurate method for quantitating the interaction of deoxyHb binding to cdb3. For this purpose, enhanced green fluorescent protein (eGFP) is fused to the COOH-terminus of cdb3, and the binding of Hb to the NH2-terminus of cdb3-eGFP is quantitated by Hb-mediated quenching of cdb3-eGFP fluorescence. As expected, the intensity of cdb3-eGFP fluorescence decreases only slightly following addition of oxyHb. However, upon deoxygenation of the same Hb-cdb3 solution, the fluorescence decreases dramatically (i.e. confirming that deoxyHb exhibits much greater affinity for cdb3 than oxyHb). Using this fluorescence quenching method, we not only confirm previously established characteristics of the Hb-cdb3 interaction, but also establish an assay that can be exploited to screen for inhibitors of the sickle Hb-cdb3 interaction that accelerates sickle Hb polymerization.
KW - Anion exchanger 1
KW - FRET analysis
KW - Hemoglobin
KW - Protein structure
KW - Red blood cells
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U2 - 10.1016/j.bcmd.2015.07.004
DO - 10.1016/j.bcmd.2015.07.004
M3 - Article
C2 - 26227857
AN - SCOPUS:84937900247
SN - 1079-9796
VL - 55
SP - 266
EP - 271
JO - Blood Cells, Molecules, and Diseases
JF - Blood Cells, Molecules, and Diseases
IS - 3
ER -