Mn2+-Sensing Mechanisms of yybP-ykoY Orphan Riboswitches

Journal Article · Sun Mar 01 00:00:00 EST 2015 · Molecular Cell

DOI:https://doi.org/10.1016/j.molcel.2015.02.016· OSTI ID:1242552

Price, Ian R.; Gaballa, Ahmed; Ding, Fang; Helmann, John D.; Ke, Ailong

Gene regulation in cis by riboswitches is prevalent in bacteria. The yybP-ykoY riboswitch family is quite widespread, yet its ligand and function remained unknown. Here in this paper, we characterize the Lactococcus lactis yybP-ykoY orphan riboswitch as a Mn2+-dependent transcription-ON riboswitch, with a ~30–40 μM affinity for Mn²⁺. We further determined its crystal structure at 2.7 Å to elucidate the metal sensing mechanism. The riboswitch resembles a hairpin, with two coaxially stacked helices tethered by a four-way junction and a tertiary docking interface. The Mn²⁺-sensing region, strategically located at the highly conserved docking interface, has two metal binding sites. Whereas one site tolerates the binding of either Mg²⁺ or Mn²⁺, the other site strongly prefers Mn²⁺ due to a direct contact from the N7 of an invariable adenosine. Lastly, mutagenesis and a Mn²⁺-free E. coli yybP-ykoY structure further reveal that Mn²⁺ binding is coupled with stabilization of the Mn2+-sensing region and the aptamer domain.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: W31-109-ENG-38; GM086766; GM102543; GM059323; RR15301; GM103485; DMR-0936384
• OSTI ID: 1242552
• Alternate ID(s): OSTI ID: 1177428; OSTI ID: 1233999
• Journal Information: Molecular Cell, Journal Name: Molecular Cell Vol. 57 Journal Issue: 6; ISSN 1097-2765
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES