EST analysis of gene expression in the tentacle of Cyanea capillata

AbstractJellyfish, Cyanea capillata, has an important position in head patterning and ion channel evolution, in addition to containing a rich source of toxins. In the present study, 2153 expressed sequence tags (ESTs) from the tentacle cDNA library of C. capillata were analyzed. The initial ESTs consisted of 198 clusters and 818 singletons, which revealed approximately 1016 unique genes in the data set. Among these sequences, we identified several genes related to head and foot patterning, voltage-dependent anion channel gene and genes related to biological activities of venom. Five kinds of proteinase inhibitor genes were found in jellyfish for the first time, and some of them were highly expressed with unknown functions

The heat-shock protein A from helicobacter pylori: bioinorganic characterization, biological significanceand evolutionary aspect

published_or_final_versionChemistryDoctoralDoctor of Philosoph

A Histidine-rich and Cysteine-rich Metal-binding Domain at the C Terminus of Heat Shock Protein A from Helicobacter pylori: IMPLICATION FOR NICKEL HOMEOSTASIS AND BISMUTH SUSCEPTIBILITY*S⃞

HspA, a member of the GroES chaperonin family, is a small protein found in Helicobacter pylori with a unique histidine- and cysteine-rich domain at the C terminus. In this work, we overexpressed, purified, and characterized this protein both in vitro and in vivo. The apo form of the protein binds 2.10 ± 0.07 Ni2+ or 1.98 ± 0.08 Bi3+ ions/monomer with a dissociation constant (Kd) of 1.1 or 5.9 × 10-19 μm, respectively. Importantly, Ni2+ can reversibly bind to the protein, as the bound nickel can be released either in the presence of a chelating ligand, e.g. EDTA, or at an acidic pH (pH½ 3.8 ± 0.2). In contrast, Bi3+ binds almost irreversibly to the protein. Both gel filtration chromatography and native electrophoresis demonstrated that apo-HspA exists as a heptamer in solution. Unexpectedly, binding of Bi3+ to the protein altered its quaternary structure from a heptamer to a dimer, indicating that bismuth may interfere with the biological functions of HspA. When cultured in Ni2+-supplemented M9 minimal medium, Escherichia coli BL21(DE3) cells expressing wild-type HspA or the C-terminal deletion mutant clearly indicated that the C terminus might protect cells from high concentrations of external Ni2+. However, an opposite phenomenon was observed when the same E. coli hosts were grown in Bi3+-supplemented medium. HspA may therefore play a dual role: to facilitate nickel acquisition by donating Ni2+ to appropriate proteins in a nickel-deficient environment and to carry out detoxification via sequestration of excess nickel. Meanwhile, HspA can be a potential target of the bismuth antiulcer drug against H. pylori