Title |
Novel nuclear targeting coiled-coil protein of Helicobacter pylori showing Ca2+-independent, Mg2+-dependent DNase I activity |
Author |
Young Chul Kwon1, Sinil Kim2, Yong Seok Lee3, Je Chul Lee4, Myung-Je Cho1, Woo-Kon Lee1, Hyung-Lyun Kang1, Jae-Young Song1, Seung Chul Baik1, and Hyeon Su Ro2* |
Address |
1Department of Microbiology, Gyeongsang National University School of Medicine, Jinju 52727, Republic of Korea, 2Division of Life Science and Research Institute of Life Sciences, Gyeongsang National University, Jinju 52828, Republic of Korea, 3Department of Life Science and Biotechnology, Soonchunhyang University, Asan 31538, Republic of Korea, 4Department of Microbiology, Kyungpook National University School of Medicine, Daegu 41944, Republic of Korea |
Bibliography |
Journal of Microbiology, 54(5),387-395, 2016,
|
DOI |
10.1007/s12275-016-5631-9
|
Key Words |
coiled-coil, DNase I, Helicobacter pylori, HP0059 |
Abstract |
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 concentrationdependent
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. |