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Crystal structure of CcpE regulatory domain in complex with citrate from Staphyloccocus aureus
Structural highlights
FunctionPublication Abstract from PubMedCatabolite control protein E (CcpE) is a LysR-type transcriptional regulator that positively regulates the transcription of the first two enzymes of the TCA cycle, namely, citZ and citB, by sensing accumulated intracellular citrate. CcpE comprises an N-terminal DNA-binding domain and a C-terminal regulatory domain (RD) and senses citrate with conserved arginine residues in the RD. Although the crystal structure of the apo SaCcpE-RD has been reported, the citrate-responsive and DNA-binding mechanisms by which CcpE regulates TCA activity remain unclear. Here, we report the crystal structure of the apo and citrate-bound SaCcpE-RDs. The SaCcpE-RD exhibits conformational changes between the two subdomains via hinge motion of the central beta4 and beta10 strands. The citrate molecule is located in a positively charged cavity between the two subdomains and interacts with the highly conserved Ser98, Leu100, Arg145, and Arg256 residues. Compared with that of the apo SaCcpE-RD, the distance between the two subdomains of the citrate-bound SaCcpE-RD is more than approximately 3 A due to the binding of the citrate molecule, and this form exhibits a closed structure. The SaCcpE-RD exhibits various citrate-binding-independent conformational changes at the contacting interface. The SaCcpE-RD prefers the dimeric state in solution, whereas the SaCcpE-FL prefers the tetrameric state. Our results provide insight into the molecular function of SaCcpE. Structural and Biochemical Analysis of the Citrate-Responsive Mechanism of the Regulatory Domain of Catabolite Control Protein E from Staphylococcus aureus.,Chen J, Shang F, Wang L, Zou L, Bu T, Jin L, Dong Y, Ha NC, Quan C, Nam KH, Xu Y Biochemistry. 2018 Oct 3. doi: 10.1021/acs.biochem.8b00671. PMID:30252448[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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