Download MendeleyC4-dicarboxylates sensing mechanism revealed by the crystal structures of DctB sensor domain.
Zhou, Y.F., Nan, B.Y., Nan, J., Ma, Q.J., Panjikar, S., Liang, Y.H., Wang, Y.P., Su, X.D.(2008) J Mol Biol 383: 49-61
- PubMed: 18725229
- DOI: https://doi.org/10.1016/j.jmb.2008.08.010
- Primary Citation of Related Structures:
3E4O, 3E4P, 3E4Q - PubMed Abstract:
C(4)-dicarboxylates are the major carbon and energy sources during the symbiotic growth of rhizobia. Responses to C(4)-dicarboxylates depend on typical two-component systems (TCS) consisting of a transmembrane sensor histidine kinase and a cytoplasmic response regulator. The DctB-DctD system is the first identified TCS for C(4)-dicarboxylates sensing. Direct ligand binding to the sensor domain of DctB is believed to be the first step of the sensing events. In this report, the water-soluble periplasmic sensor domain of Sinorhizobium meliloti DctB (DctBp) was studied, and three crystal structures were solved: the apo protein, a complex with C(4) succinate, and a complex with C(3) malonate. Different from the two structurally known CitA family of carboxylate sensor proteins CitA and DcuS, the structure of DctBp consists of two tandem Per-Arnt-Sim (PAS) domains and one N-terminal helical region. Only the membrane-distal PAS domain was found to bind the ligands, whereas the proximal PAS domain was empty. Comparison of DctB, CitA, and DcuS suggests a detailed stereochemistry of C(4)-dicarboxylates ligand perception. The structures of the different ligand binding states of DctBp also revealed a series of conformational changes initiated upon ligand binding and propagated to the N-terminal domain responsible for dimerization, providing insights into understanding the detailed mechanism of the signal transduction of TCS histidine kinases.
Organizational Affiliation:
National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China.
