Download MendeleyAlternative binding modes of l-histidine guided by metal ions for the activation of the antiterminator protein HutP of Bacillus subtilis.
Dhakshnamoorthy, B., Mizuno, H., Kumar, P.K.R.(2013) J Struct Biol 183: 512-518
- PubMed: 23748184
- DOI: https://doi.org/10.1016/j.jsb.2013.05.019
- Primary Citation of Related Structures:
4H4L - PubMed Abstract:
Anti-terminator proteins control gene expression by recognizing control signals within cognate transcripts and then preventing transcription termination. HutP is such a regulatory protein that regulates the expression of the histidine utilization (hut) operon in Bacillus subtilis by binding to cis-acting regulatory sequences in hut mRNAs. During the anti-termination process, l-histidine and a divalent ion are required for hutP to bind to the specific sequence within the hut mRNA. Our previous crystal structure of the HutP-l-histidine-Mg(2+)-RNA ternary complex demonstrated that the l-histidine ligand and Mg(2+) bind together such that the backbone nitrogen and carboxyl oxygen of l-histidine coordinate with Mg(2+). In addition to the Mg(2+), other divalent ions are also known to efficiently support the l-histidine-dependent anti-termination of the hut operon, and the best divalent ion is Zn(2+). In this study, we determined the crystal structure of the HutP-l-histidine-Zn(2+) complex and found that the orientation of l-histidine coordinated to Zn(2+) is reversed relative to that of l-histidine coordinated to Mg(2+), i.e., the imidazole side chain nitrogen of l-histidine coordinates to Zn(2+). This alternative binding mode of the l-histidine ligand to a divalent ion provides further insight into the mechanisms responsible for the activation of RNA binding during the hut anti-termination process.
Organizational Affiliation:
RNA Processing Group, Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Central-6, 1-1-1 Higashi, Tsukuba 305-8566, Japan.
