The important and diverse regulatory roles of Ca2+in eukaryotes are conveyed by the EF-hand containing calmodulin superfamily.However,the calcium-regulatory proteins in prokaryotes are still poorly understood.In this ...The important and diverse regulatory roles of Ca2+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-terminalα-helix,unpaired ligand-binding EF-hands and the lack of the extreme Cterminal 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.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.30400259,30221003)the National Basic Research Program(973 Program)(Grant No.2007CB914301)the Tianjin Municipal Science and Technology Commission(Grant No.08SYSYTC00200).
文摘The important and diverse regulatory roles of Ca2+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-terminalα-helix,unpaired ligand-binding EF-hands and the lack of the extreme Cterminal 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.
