Neutralization of toxic haem by Porphyromonas gingivalis haemoglobin receptor.

Abstract	Free haem is known to be toxic to organs, tissues and cells. It enhances permeability by binding to a cell membrane, which leads to cell death, and damages lipids, proteins and DNA through the generation of reactive oxygen species. Lysine- and arginine-specific gingipains (Kgp and RgpA/B) are major proteinases that play an important role in the pathogenicity of a black-pigmented periodontopathogen named Porphyromonas gingivalis. One of the adhesin domains of gingipain, HbR could bind haem as an iron nutrient source for P. gingivalis. Using erythrocyte and its membrane as a model, results from the present study demonstrate that recombinant HbR expressed in Escherichia coli could inhibit haem-induced haemolysis, probably through removing haem from the haem-membrane complex and lowering free haem toxicity by mediating dimerization of haem molecules. The ability to protect a cell membrane from haem toxicity is a new function for HbR.
Authors	Nguyen Thanh Thuy Nhien, Nguyen Tien Huy, Mariko Naito, Tatsuo Oida, Dinh Thanh Uyen, Mingguo Huang, Mihoko Kikuchi, Shigeharu Harada, Koji Nakayama, Kenji Hirayama, Kaeko Kamei
Journal	Journal of biochemistry (J Biochem) Vol. 147 Issue 3 Pg. 317-25 (Mar 2010) ISSN: 1756-2651 [Electronic] England
PMID	19861401 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References	Adhesins, Bacterial Gingipain Cysteine Endopeptidases Haptoglobins Recombinant Proteins Serum Albumin, Bovine Heme Cysteine Endopeptidases
Topics	Adhesins, Bacterial (chemistry, genetics, metabolism) Cell Membrane (metabolism) Cysteine Endopeptidases (chemistry, genetics, metabolism) Erythrocytes (metabolism, pathology, ultrastructure) Escherichia coli (metabolism) Gingipain Cysteine Endopeptidases Haptoglobins (metabolism) Heme (metabolism) Hemolysis Humans Lipid Peroxidation Porphyromonas gingivalis (genetics, metabolism) Protein Binding Protein Structure, Tertiary Recombinant Proteins (biosynthesis, genetics) Serum Albumin, Bovine (metabolism)

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