title: Change in single cystathionine β-synthase domain-containing protein from a bent to flat conformation upon adenosine monophosphate binding.
abstract: Cystathionine β-synthase (CBS) domains are small intracellular modules that can act as binding domains for adenosine derivatives, and they may regulate the activity of associated enzymes or other functional domains. Among these, the single CBS domain-containing proteins, CBSXs, from Arabidopsis thaliana, have recently been identified as redox regulators of the thioredoxin system. Here, the crystal structure of CBSX2 in complex with adenosine monophosphate (AMP) is reported at 2.2Å resolution. The structure of dimeric CBSX2 with bound-AMP is shown to be approximately flat, which is in stark contrast to the bent form of apo-CBSXs. This conformational change in quaternary structure is triggered by a local structural change of the unique α5 helix, and by moving each loop P into an open conformation to accommodate incoming ligands. Furthermore, subtle rearrangement of the dimer interface triggers movement of all subunits, and consequently, the bent structure of the CBSX2 dimer becomes a flat structure. This reshaping of the structure upon complex formation with adenosine-containing ligand provides evidence that ligand-induced conformational reorganization of antiparallel CBS domains is an important regulatory mechanism.
authors.affiliation: School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, South Korea.
authors.forename: Byung-Cheon
authors.initials: BC
authors.lastname: Jeong
authors.forename: Si Hoon
authors.initials: SH
authors.lastname: Park
authors.forename: Kyoung Shin
authors.initials: KS
authors.lastname: Yoo
authors.forename: Jeong Sheop
authors.initials: JS
authors.lastname: Shin
authors.forename: Hyun Kyu
authors.initials: HK
authors.lastname: Song
mesh_terms: D000249:Adenosine Monophosphate / Q000737:chemistry*; D029681:Arabidopsis Proteins / Q000737:chemistry*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003541:Cystathionine beta-Synthase / Q000737:chemistry*; D019281:Dimerization; D008958:Models, Molecular; D017434:Protein Structure, Tertiary
chemical_list: D029681:Arabidopsis Proteins; D000249:Adenosine Monophosphate; C573048:CBSX2 protein, Arabidopsis; D003541:Cystathionine beta-Synthase
keywords: AMP; AP(4)A; Arabidopsis thaliana; Bateman domain; CBS; CBS domain; CBSX2; CDCP; Conformational change; Crystal structure; RMSD; S-adenosyl-l-methionine; SAM; Trx; adenosine monophosphate; cystathionine β-synthase; cystathionine β-synthase domain-containing protein; diadenosine 5′,5-P1,P4-tetraphosphate; root-mean-square deviation; thioredoxin