C4-dicarboxylates sensing mechanism revealed by the crystal structures of DctB sensor domain

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.

Nan, Beiyan (författare)
Nan, JieLund University,Lunds universitet,MAX IV-laboratoriet,MAX IV Laboratory(Swepub:lu)maxl-jna (författare)
Ma, Qingjun (författare)
Panjikar, Santosh (författare)
Liang, Yu-He (författare)
Wang, Yiping (författare)
Su, Xiao-DongLund University,Lunds universitet,Biokemi och Strukturbiologi,Centrum för Molekylär Proteinvetenskap,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Biochemistry and Structural Biology,Center for Molecular Protein Science,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH(Swepub:lu)mbfys-xs (författare)
Lunds universitetMAX IV-laboratoriet (creator_code:org_t)

Ingår i:Journal of Molecular Biology: Elsevier BV383:1, s. 49-611089-86380022-2836

Av författaren/redakt...: Zhou, Yan-Feng; Nan, Beiyan; Nan, Jie; Ma, Qingjun; Panjikar, Santos ...; Liang, Yu-He; visa fler...; Wang, Yiping; Su, Xiao-Dong; visa färre...

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