title: Structural Studies of Potassium Transport Protein KtrA Regulator of Conductance of K+ (RCK) C Domain in Complex with Cyclic Diadenosine Monophosphate (c-di-AMP).
abstract: Although it was only recently identified as a second messenger, c-di-AMP was found to have fundamental importance in numerous bacterial functions such as ion transport. The potassium transporter protein, KtrA, was identified as a c-di-AMP receptor. However, the co-crystallization of c-di-AMP with the protein has not been studied. Here, we determined the crystal structure of the KtrA RCK_C domain in complex with c-di-AMP. The c-di-AMP nucleotide, which adopts a U-shaped conformation, is bound at the dimer interface of RCK_C close to helices α3 and α4. c-di-AMP interacts with KtrA RCK_C mainly by forming hydrogen bonds and hydrophobic interactions. c-di-AMP binding induces the contraction of the dimer, bringing the two monomers of KtrA RCK_C into close proximity. The KtrA RCK_C was able to interact with only c-di-AMP, but not with c-di-GMP, 3',3-cGAMP, ATP, and ADP. The structure of the KtrA RCK_C domain and c-di-AMP complex would expand our understanding about the mechanism of inactivation in Ktr transporters governed by c-di-AMP.
authors.affiliation: From the Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
authors.forename: Henna
authors.initials: H
authors.lastname: Kim
authors.affiliation: From the Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
authors.forename: Suk-Jun
authors.initials: SJ
authors.lastname: Youn
authors.affiliation: From the Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
authors.forename: Seong Ok
authors.initials: SO
authors.lastname: Kim
authors.affiliation: From the Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
authors.forename: Junsang
authors.initials: J
authors.lastname: Ko
authors.affiliation: From the Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea jieoh@kaist.ac.kr.
authors.forename: Jie-Oh
authors.initials: JO
authors.lastname: Lee
authors.affiliation: From the Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea byongseok.choi@kaist.ac.kr.
authors.forename: Byong-Seok
authors.initials: BS
authors.lastname: Choi
mesh_terms: D001412:Bacillus subtilis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015226:Dinucleoside Phosphates / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D011188:Potassium / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D027682:Cation Transport Proteins; D015226:Dinucleoside Phosphates; C528998:cyclic diadenosine phosphate; D011188:Potassium
keywords: Staphylococcus aureus (S. aureus); bacterial signal transduction; crystal structure; cyclic diadenosine monophosphate (c-di-AMP); isothermal titration calorimetry (ITC); potassium transport