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Crystal structure of CcpE regulatory domain in complex with citrate from Staphyloccocus aureusCrystal 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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