Cover: Anti-terminator proteins control gene expression by recognizing control signals on cognate transcripts and preventing transcriptional termination, which would otherwise occur at sites that may be for downstream. One such protein is HutP, an antiterminator protein that regulates the histidine utilization (hut) operon in Bacillus subtilis. Recently, a quaternary complex crystal structure of HutP at 1.60 Å resolution [HutP-RNA-L-histidine-Mg2+; Nature (2005) 434, 183–191] has been solved. Considering various structural and biochemical studies on HutP regulation of the hut operon in B.subtilis have revealed how the protein undergoes conformational changes in response to two key components: L-histidine and Mg2+ ions. In this issue, we showed various metal ions mediate the hut RNA-HutP interactions to regulate the structural changes within the HutP {see article by Kumarevel et al. in this issue [Nucleic Acids Res. (2005) 33, 5494–5502]}. The hexameric HutP and RNA are shown in ribbons and cpk models, respectively. The image was created with the software Molscript and raster 3D.
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