Abstract
α-Hemoglobin (αHb) stabilizing protein (AHSP) is expressed in erythropoietic tissues as an accessory factor in hemoglobin synthesis. AHSP forms a specific complex with αHb and suppresses the heme-catalyzed evolution of reactive oxygen species by converting αHb to a conformation in which the heme is coordinated at both axial positions by histidine side chains (bis-histidyl coordination). Currently, the detailed mechanism by which AHSP induces structural changes in αHb has not been determined. Here, we present x-ray crystallography, NMR spectroscopy, and mutagenesis data that identify, for the first time, the importance of an evolutionarily conserved proline, Pro30, in loop 1 of AHSP. Mutation of Pro30 to a variety of residue types results in reduced ability to convert αHb. In complex with-Hb, AHSP Pro30 adopts a cis-peptidyl conformation and makes contact with the N terminus of helix G in αHb. Mutations that stabilize the cis-peptidyl conformation of free AHSP, also enhance the αHb conversion activity. These findings suggest that AHSP loop 1 can transmit structural changes to the heme pocket of αHb, and, more generally, highlight the importance of cis-peptidyl prolyl residues in defining the conformation of regulatory protein loops.
| Original language | English |
|---|---|
| Pages (from-to) | 29462-29469 |
| Number of pages | 8 |
| Journal | Journal of Biological Chemistry |
| Volume | 284 |
| Issue number | 43 |
| DOIs | |
| Publication status | Published - 23 Oct 2009 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Biochemistry
- Cell Biology
- Molecular Biology
Cite this
A cis-proline in α-hemoglobin stabilizing protein directs the structural reorganization of α-hemoglobin. / Gell, David A.; Feng, Liang; Zhou, Suiping; Jeffrey, Philip D.; Bendak, Katerina; Gow, Andrew; Weiss, Mitchell J.; Shi, Yigong; Mackay, Joel P.
In: Journal of Biological Chemistry, Vol. 284, No. 43, 23.10.2009, p. 29462-29469.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A cis-proline in α-hemoglobin stabilizing protein directs the structural reorganization of α-hemoglobin
AU - Gell, David A.
AU - Feng, Liang
AU - Zhou, Suiping
AU - Jeffrey, Philip D.
AU - Bendak, Katerina
AU - Gow, Andrew
AU - Weiss, Mitchell J.
AU - Shi, Yigong
AU - Mackay, Joel P.
PY - 2009/10/23
Y1 - 2009/10/23
N2 - α-Hemoglobin (αHb) stabilizing protein (AHSP) is expressed in erythropoietic tissues as an accessory factor in hemoglobin synthesis. AHSP forms a specific complex with αHb and suppresses the heme-catalyzed evolution of reactive oxygen species by converting αHb to a conformation in which the heme is coordinated at both axial positions by histidine side chains (bis-histidyl coordination). Currently, the detailed mechanism by which AHSP induces structural changes in αHb has not been determined. Here, we present x-ray crystallography, NMR spectroscopy, and mutagenesis data that identify, for the first time, the importance of an evolutionarily conserved proline, Pro30, in loop 1 of AHSP. Mutation of Pro30 to a variety of residue types results in reduced ability to convert αHb. In complex with-Hb, AHSP Pro30 adopts a cis-peptidyl conformation and makes contact with the N terminus of helix G in αHb. Mutations that stabilize the cis-peptidyl conformation of free AHSP, also enhance the αHb conversion activity. These findings suggest that AHSP loop 1 can transmit structural changes to the heme pocket of αHb, and, more generally, highlight the importance of cis-peptidyl prolyl residues in defining the conformation of regulatory protein loops.
AB - α-Hemoglobin (αHb) stabilizing protein (AHSP) is expressed in erythropoietic tissues as an accessory factor in hemoglobin synthesis. AHSP forms a specific complex with αHb and suppresses the heme-catalyzed evolution of reactive oxygen species by converting αHb to a conformation in which the heme is coordinated at both axial positions by histidine side chains (bis-histidyl coordination). Currently, the detailed mechanism by which AHSP induces structural changes in αHb has not been determined. Here, we present x-ray crystallography, NMR spectroscopy, and mutagenesis data that identify, for the first time, the importance of an evolutionarily conserved proline, Pro30, in loop 1 of AHSP. Mutation of Pro30 to a variety of residue types results in reduced ability to convert αHb. In complex with-Hb, AHSP Pro30 adopts a cis-peptidyl conformation and makes contact with the N terminus of helix G in αHb. Mutations that stabilize the cis-peptidyl conformation of free AHSP, also enhance the αHb conversion activity. These findings suggest that AHSP loop 1 can transmit structural changes to the heme pocket of αHb, and, more generally, highlight the importance of cis-peptidyl prolyl residues in defining the conformation of regulatory protein loops.
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UR - http://www.scopus.com/inward/citedby.url?scp=70350365377&partnerID=8YFLogxK
U2 - 10.1074/jbc.M109.027045
DO - 10.1074/jbc.M109.027045
M3 - Article
VL - 284
SP - 29462
EP - 29469
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 43
ER -