Heme Oxidation in a Chimeric Protein of the -Selective Neisseriae meningitidis Heme Oxygenase with the Distal Helix of the
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- 作者：Rahul Deshmukh ; Yuhong Zeng ; Lena M. Furci ; Hong-wei Huang ; Bailey N. Morgan ; Suzanne Sander ; Aileen Y. Alontaga ; Richard A. Bunce ; Pierre Moë ; nne-Loccoz ; Mario Rivera ; and Angela Wilks
- 刊名：Biochemistry
- 出版年：2005
- 出版时间：October 25, 2005
- 年：2005
- 卷：44
- 期：42
- 页码：13713 - 13723
- 全文大小：383K
- 年卷期：v.44,no.42(October 25, 2005)
- ISSN：1520-4995
文摘
Heme oxygenases from the bacterial pathogens Neisseriae meningitidis (nm-HO) andPseudomonas aeruginosa (pa-HO) share significant sequence identity (37%). In nm-HO, biliverdin IX
is the sole product of the reaction, whereas pa-HO yields predominantly biliverdin IX
. We have previouslyshown by NMR that the in-plane conformation of the heme in pa-HO is significantly different from thatof nm-HO as a result of distinct interactions of the heme propionates with the protein scaffold [Caignan,G. A., Deshmukh, R., Wilks, A., Zeng, Y., Huang, H. W., Moenne-Loccoz, P., Bunce, R. A., Eastman,M. A., and Rivera, M. (2002) J. Am. Chem. Soc. 124, 14879-14892]. In the report presented here, wehave extended these studies to investigate the role of the distal helix by preparing a chimera of nm-HO(nm-HOch), in which distal helix residues 107-142 of nm-HO have been replaced with the correspondingresidues of the -regioselective pa-HO (112-147). Electronic absorption spectra, resonance Raman andFTIR spectroscopic studies confirm that the orientation and hydrogen bonding properties of the proximalHis ligand are not significantly altered in the chimera relative those of the wild-type proteins. The catalyticturnover of the nm-HOch-heme complex yields almost exclusively -biliverdin and a small but reproducibleamount of -biliverdin. NMR spectroscopic studies reveal that the altered regioselectivity in the chimericprotein likely stems from a dynamic equilibrium between two alternate in-plane conformations of theheme (in-plane heme disorder). Replacement of K16 with Ala and Met31 with Lys in the chimeric proteinin an effort to tune key polypeptide-heme propionate contacts largely stabilizes the in-plane conformerconducive to -meso hydroxylation.
is the sole product of the reaction, whereas pa-HO yields predominantly biliverdin IX. We have previouslyshown by NMR that the in-plane conformation of the heme in pa-HO is significantly different from thatof nm-HO as a result of distinct interactions of the heme propionates with the protein scaffold [Caignan,G. A., Deshmukh, R., Wilks, A., Zeng, Y., Huang, H. W., Moenne-Loccoz, P., Bunce, R. A., Eastman,M. A., and Rivera, M. (2002) J. Am. Chem. Soc. 124, 14879-14892]. In the report presented here, wehave extended these studies to investigate the role of the distal helix by preparing a chimera of nm-HO(nm-HOch), in which distal helix residues 107-142 of nm-HO have been replaced with the correspondingresidues of the -regioselective pa-HO (112-147). Electronic absorption spectra, resonance Raman andFTIR spectroscopic studies confirm that the orientation and hydrogen bonding properties of the proximalHis ligand are not significantly altered in the chimera relative those of the wild-type proteins. The catalyticturnover of the nm-HOch-heme complex yields almost exclusively -biliverdin and a small but reproducibleamount of -biliverdin. NMR spectroscopic studies reveal that the altered regioselectivity in the chimericprotein likely stems from a dynamic equilibrium between two alternate in-plane conformations of theheme (in-plane heme disorder). Replacement of K16 with Ala and Met31 with Lys in the chimeric proteinin an effort to tune key polypeptide-heme propionate contacts largely stabilizes the in-plane conformerconducive to -meso hydroxylation.© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |