%A Chengliang Chai, You Yu, Wei Zhuo, Haifeng Zhao, Xiaolu Li, Na Wang, Jijie Chai, Maojun Yang %T Structural basis for a homodimeric ATPase subunit of an ECF transporter %0 Journal Article %D 2013 %J Protein Cell %J Protein & Cell %@ 1674-800X %R 10.1007/s13238-013-3915-y %P 793-801 %V 4 %N 10 %U {https://journal.hep.com.cn/pac/EN/10.1007/s13238-013-3915-y %8 2013-10-01 %X

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 belongs to type-1 energy-coupling factor (ECF) transporters and is a widespread group of microbial cobalt transporters. CbiO is the ATPase subunit (A-component) of the cobalt transporting system in the gram-negative thermophilic bacterium Thermoanaerobacter tengcongensis. Here we report the crystal structure of a nucleotide-free CbiO at a resolution of 2.3 ?. CbiO contains an N-terminal canonical nucleotide-binding domain (NBD) and C-terminal 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 domains result in formation of a four-helix bundle. Structural comparison with other ECF transporters suggests that non-conserved residues outside the T-component binding 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 organization and interaction of the CbiMNQO system.