Novel nuclear targeting coiled-coil protein of Helicobacter pylori showing Ca(2+)-independent, Mg(2+)-dependent DNase I activity.
HP0059, an uncharacterized gene of Helicobacter pylori, encodes a 284-aa-long protein containing a nuclear localization sequence (NLS) and multiple leucine-rich heptad repeats. Effects of HP0059 proteins in human stomach cells were assessed by incubation of recombinant HP0059 proteins with the AGS human gastric carcinoma cell line. Wild-type HP0059 proteins showed cytotoxicity in AGS cells in a concentration-dependent manner, whereas NLS mutant protein showed no effect, suggesting that the cytotoxicity is attributed to host nuclear localization. AGS cells transfected with pEGFP-HP0059 plasmid showed strong GFP signal merged to the chromosomal DNA region. The chromosome was fragmented into multiple distinct dots merged with the GFP signal after 12 h of incubation. The chromosome fragmentation was further explored by incubation of AGS chromosomal DNA with recombinant HP0059 proteins, which leaded to complete degradation of the chromosomal DNA. HP0059 protein also degraded circular plasmid DNA without consensus, being an indication of DNase I activity. The DNase was activated by MgCl2, but not by CaCl2. The activity was completely blocked by EDTA. The optimal pH and temperature for DNase activity were 7.0-8.0 and 55°C, respectively. These results indicate that HP0059 possesses a novel DNase I activity along with a role in the genomic instability of human gastric cells, which may result in the transformation of gastric cells.
Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, 52727, Republic of Korea.
Young Chul
YC
Kwon
Division of Life Science and Research Institute of Life Sciences, Gyeongsang National University, Jinju, 52828, Republic of Korea.
Sinil
S
Kim
Department of Life Science and Biotechnology, Soonchunhyang University, Asan, 31538, Republic of Korea.
Yong Seok
YS
Lee
Department of Microbiology, Kyungpook National University School of Medicine, Daegu, 41944, Republic of Korea.
Je Chul
JC
Lee
Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, 52727, Republic of Korea.
Myung-Je
MJ
Cho
Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, 52727, Republic of Korea.
Woo-Kon
WK
Lee
Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, 52727, Republic of Korea.
Hyung-Lyun
HL
Kang
Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, 52727, Republic of Korea.
Jae-Young
JY
Song
Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, 52727, Republic of Korea. scbaik@gnu.ac.kr.
Seung Chul
SC
Baik
Division of Life Science and Research Institute of Life Sciences, Gyeongsang National University, Jinju, 52828, Republic of Korea. rohyeon@gnu.ac.kr.
Hyeon Su
HS
Ro
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D003850:Deoxyribonuclease I / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D004789:Enzyme Activation; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D021381:Protein Transport; D011994:Recombinant Proteins / Q000494:pharmacology; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000378:metabolism; D014162:Transfection
D001426:Bacterial Proteins; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D003850:Deoxyribonuclease I
DNase I; HP0059; Helicobacter pylori; coiled-coil