Andrew VanBenschoten

Massachusetts Institute of Technology

Drennan Laboratory
Mentor: Christine Phillips

Summer 2008

Crystallographic Investigations of the Regulatory Proteins YjiA and HpNikR

YjiA is a dual-domain P-loop NTP-binding protein that is present in many bacteria and eukaryotes and is overexpressed in response to DNA damage.   Although the protein has yet to be fully characterized, recent structural studies suggest that YjiA acts as a regulatory G-protein.   As such, we crystallized GDP and GTP bound to YjiA, in order to obtain the respective molecular structures.   These "metabolic snapshots" will enable better understanding of YjiA's underlying regulatory mechanisms.   It has also been shown that YjiA will bind to both Zn 2+ and Ni 2+ .   We have obtained crystals of Zn 2+ -bound YjiA and are screening for a crystallization condition for Ni 2+ -YjiA in order to investigate the morphological changes pertaining to the presence of either ion.

Proper regulation of metal ion concentration in the cell is critical to the survival of every living species. NikR, a tetrameric RHH (Ribbon-Helix-Helix) transcription factor, assists numerous prokaryotes with divalent nickel regulation.   Our lab is currently investigating the NikR homolog from Helicobacter Pylori (HpNikR).   Although crystals of Ni 2+ -bound HpNikR have previously been obtained, better crystals are needed to improve the resolution of the current structure.   Thus, we have screened Ni 2+ -HpNikR for more suitable crystallization conditions in hopes of gaining insight into the effects of nickel binding to the protein structure.