title: Structural basis for prokaryotic calcium-mediated regulation by a Streptomyces coelicolor calcium binding protein.
abstract: The important and diverse regulatory roles of Ca(2+) in eukaryotes are conveyed by the EF-hand containing calmodulin superfamily. However, the calcium-regulatory proteins in prokaryotes are still poorly understood. In this study, we report the three-dimensional structure of the calcium-binding protein from Streptomyces coelicolor, named CabD, which shares low sequence homology with other known helix-loop-helix EF-hand proteins. The CabD structure should provide insights into the biological role of the prokaryotic calcium-binding proteins. The unusual structural features of CabD compared with prokaryotic EF-hand proteins and eukaryotic sarcoplasmic calcium-binding proteins, including the bending conformation of the first C-terminal α-helix, unpaired ligand-binding EF-hands and the lack of the extreme C-terminal loop region, suggest it may have a distinct and significant function in calcium-mediated bacterial physiological processes, and provide a structural basis for potential calcium-mediated regulatory roles in prokaryotes.
authors.affiliation: Laboratory of Structural Biology, Tsinghua University, Beijing 100084, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhao
authors.forename: Hai
authors.initials: H
authors.lastname: Pang
authors.forename: Shenglan
authors.initials: S
authors.lastname: Wang
authors.forename: Weihong
authors.initials: W
authors.lastname: Zhou
authors.forename: Keqian
authors.initials: K
authors.lastname: Yang
authors.forename: Mark
authors.initials: M
authors.lastname: Bartlam
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002118:Calcium / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D020832:EF Hand Motifs; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D048372:Streptomyces coelicolor; D040681:Structural Homology, Protein; D013499:Surface Properties
chemical_list: D002135:Calcium-Binding Proteins; D002118:Calcium