tailieunhanh - Báo cáo khoa học: Structure, regulation and evolution of Nox-family NADPH oxidases that produce reactive oxygen species

NADPH oxidases of the Nox family exist in various supergroups of eukaryotes but not in prokaryotes, and play crucial roles in a variety of biological processes, such as host defense, signal transduction, and hor-mone synthesis. | IFEBS Journal REVIEW ARTICLE Structure regulation and evolution of Nox-family NADPH oxidases that produce reactive oxygen species Hideki Sumimoto Medical institute of Bioregulation Kyushu University Fukuoka CREST Japan Science and Technology Agency Tokyo Japan Keywords Duox Nox Noxal Noxol p22phox p40phox p47phox p67phox Rac Rboh Correspondence H. Sumimoto Medical institute of Bioregulation Kyushu University 3-1-1 Maidashi Higashi-ku Fukuoka 812-8582 Japan Fax 81 92 642 6807 Tel 81 92 642 6806 E-mail hsumi@ Received 8 January 2008 revised 2 April 2008 accepted 30 April 2008 doi NADPH oxidases of the Nox family exist in various supergroups of eukaryotes but not in prokaryotes and play crucial roles in a variety of biological processes such as host defense signal transduction and hormone synthesis. In conjunction with NADPH oxidation Nox enzymes reduce molecular oxygen to superoxide as a primary product and this is further converted to various reactive oxygen species. The electron-transferring system in Nox is composed of the C-terminal cytoplasmic region homologous to the prokaryotic and organelle enzyme ferredoxin reductase and the N-terminal six transmembrane segments containing two hemes a structure similar to that of cytochrome b of the mitochondrial bc1 complex. During the course of eukaryote evolution Nox enzymes have developed regulatory mechanisms depending on their functions by inserting a regulatory domain or motif into their own sequences or by obtaining a tightly associated protein as a regulatory subunit. For example one to four Ca2 -binding EF-hand motifs are present at the N-termini in several subfamilies such as the respiratory burst oxidase homolog Rboh subfamily in land plants the supergroup Plantae the NoxC subfamily in social amoebae the Amoebozoa and the Nox5 and dual oxidase Duox subfamilies in animals the Opisthokonta whereas an SH3 domain is inserted into the ferredoxin-NADP reductase .