TAILIEUCHUNG - Báo cáo khoa học: Helicobacter pylori neutrophil-activating protein activates neutrophils by its C-terminal region even without dodecamer formation, which is a prerequisite for DNA protection – novel approaches against Helicobacter pylori inflammation

Helicobacter pylorineutrophil-activating protein (HP-NAP) protects DNA from free radicals as a dodecamer through its ferroxidase activity without, however, directly binding to it. The retardation that was observed at pH could be easily attributed to an iron effect, as it was revealed by experiments in the absence of HP-NAP. | ễFEBS Journal Helicobacter pylori neutrophil-activating protein activates neutrophils by its C-terminal region even without dodecamer formation which is a prerequisite for DNA protection - novel approaches against Helicobacter pylori inflammation Filippos Kottakis1 Georgios Papadopoulos2 Eleni V. Pappa3 Paul Cordopatis3 Stefanos Pentas1 and Theodora Choli-Papadopoulou1 1 Laboratory of Biochemistry Schoolof Chemistry Aristotle University of Thessaloniki Greece 2 Department of Biochemistry and Biotechnology University of Thessaly Larissa Greece 3 Department of Pharmacy University of Patras Greece Keywords DNA binding Helicobacter pylori HP-NAP neutrophil activation Correspondence T. Choli-Papadopoulou Laboratory of Biochemistry Schoolof Chemistry Aristotle University of Thessaloniki TK 54124 Thessaloniki Greece Fax 302310 99768 Tel 302310 997806 E-mail tcholi@ Received 13 July 2007 revised 9 November 2007 accepted 20 November 2007 doi Helicobacter pylori neutrophil-activating protein HP-NAP protects DNA from free radicals as a dodecamer through its ferroxidase activity without however directly binding to it. The retardation that was observed at pH could be easily attributed to an iron effect as it was revealed by experiments in the absence of HP-NAP. A total loss of ferroxidase activity dodecamer formation and DNA protection in environments rich in free radicals was observed after replacement of His25 His37 Asp52 and Lys134 which are located within the ferroxidase site with Ala. Molecular dynamics simulations revealed that dimer formation is highly unlikely following mutation of the above amino acids as the Fe2 is no longer attracted with equal strength by both subunits. These findings probably indicate that iron plays an important role in the conformation of HP-NAP by initiating the formation of stable dimers that are indispensable for the ensuing dodecamer structure. Very surprisingly neutrophil activation appeared .

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