TY - JOUR
T1 - Histidine residues are important for preserving the structure and heme binding to the C. elegans HRG-3 heme-trafficking protein
AU - Marciano, Ortal
AU - Moskovitz, Yoni
AU - Hamza, Iqbal
AU - Ruthstein, Sharon
N1 - Publisher Copyright: © 2015 SBIC.
PY - 2015/12/1
Y1 - 2015/12/1
N2 - C. elegans is a heme auxotroph that requires environmental heme for sustenance. As such, worms utilize HRG-3, a small heme-trafficking protein, to traffic heme from the intestine to extra-intestinal tissues and embryos. However, how HRG-3 binds and delivers heme remains unknown. In this study, we utilized electron paramagnetic resonance spectroscopy together with site-directed spin labeling, absorption spectroscopy, circular dichroism, and mutagenesis to gain structural and molecular insights into HRG-3. We showed that HRG-3 is a dimer, whereas H9 and H10 are significant residues that preserve a specific conformational state in the HRG-3 dimer. In the absence of H9 and H10, HRG-3 can still bind heme, although with a different affinity. Furthermore, the heme-binding site is closer to the N-termini than to the C-termini. Taken together, our results lay the groundwork for future mechanistic and structural studies of HRG-3 and inter-tissue heme trafficking in metazoans.
AB - C. elegans is a heme auxotroph that requires environmental heme for sustenance. As such, worms utilize HRG-3, a small heme-trafficking protein, to traffic heme from the intestine to extra-intestinal tissues and embryos. However, how HRG-3 binds and delivers heme remains unknown. In this study, we utilized electron paramagnetic resonance spectroscopy together with site-directed spin labeling, absorption spectroscopy, circular dichroism, and mutagenesis to gain structural and molecular insights into HRG-3. We showed that HRG-3 is a dimer, whereas H9 and H10 are significant residues that preserve a specific conformational state in the HRG-3 dimer. In the absence of H9 and H10, HRG-3 can still bind heme, although with a different affinity. Furthermore, the heme-binding site is closer to the N-termini than to the C-termini. Taken together, our results lay the groundwork for future mechanistic and structural studies of HRG-3 and inter-tissue heme trafficking in metazoans.
KW - Absorption spectroscopy
KW - EPR
KW - HRG-3
KW - Heme transfer
KW - Site-directed spin labeling
UR - http://www.scopus.com/inward/record.url?scp=84948417275&partnerID=8YFLogxK
U2 - https://doi.org/10.1007/s00775-015-1304-0
DO - https://doi.org/10.1007/s00775-015-1304-0
M3 - مقالة
C2 - 26531103
SN - 0949-8257
VL - 20
SP - 1253
EP - 1261
JO - Journal of Biological Inorganic Chemistry
JF - Journal of Biological Inorganic Chemistry
IS - 8
ER -