The transition metal cobalt,an essential cofactor for many enzymes in prokaryotes,is taken up by several specifi c transport systems.The CbiMNQO protein complex be-longs to type-1 energy-coupling factor(ECF)transporte...The transition metal cobalt,an essential cofactor for many enzymes in prokaryotes,is taken up by several specifi c transport systems.The CbiMNQO protein complex be-longs to type-1 energy-coupling factor(ECF)transporters and is a widespread group of microbial cobalt transport-ers.CbiO is the ATPase subunit(A-component)of the cobalt transporting system in the gram-negative thermo-philic bacterium Thermoanaerobacter tengcongensis.Here we report the crystal structure of a nucleotide-free CbiO at a resolution of 2.3Å.CbiO contains an N-terminal canonical nucleotide-binding domain(NBD)and C-termi-nal helical domain.Structural and biochemical data show that CbiO forms a homodimer mediated by the NBD and the C-terminal domain.Interactions mainly via conserved hydrophobic amino acids between the two C-terminal do-mains result in formation of a four-helix bundle.Structural comparison with other ECF transporters suggests that non-conserved residues outside the T-component bind-ing groove in the A component likely act as a specifi city determinant for T components.Together,our data provide information on understanding of the structural organiza-tion and interaction of the CbiMNQO system.展开更多
基金the National Basic Research Program(973 Program)(Nos.2011CB910502 and 2012CB911101)the National Natural Science Foundation of China(Grant Nos.31030020 and 31170679).
文摘The transition metal cobalt,an essential cofactor for many enzymes in prokaryotes,is taken up by several specifi c transport systems.The CbiMNQO protein complex be-longs to type-1 energy-coupling factor(ECF)transporters and is a widespread group of microbial cobalt transport-ers.CbiO is the ATPase subunit(A-component)of the cobalt transporting system in the gram-negative thermo-philic bacterium Thermoanaerobacter tengcongensis.Here we report the crystal structure of a nucleotide-free CbiO at a resolution of 2.3Å.CbiO contains an N-terminal canonical nucleotide-binding domain(NBD)and C-termi-nal helical domain.Structural and biochemical data show that CbiO forms a homodimer mediated by the NBD and the C-terminal domain.Interactions mainly via conserved hydrophobic amino acids between the two C-terminal do-mains result in formation of a four-helix bundle.Structural comparison with other ECF transporters suggests that non-conserved residues outside the T-component bind-ing groove in the A component likely act as a specifi city determinant for T components.Together,our data provide information on understanding of the structural organiza-tion and interaction of the CbiMNQO system.