3n5b

The complex of PII and PipX from Anabaena

spinqualitylabelsall models 3n5b, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3n5b is a 2 chain structure with sequence from Nostoc sp. PCC 7120 = FACHB-418. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.9Å Ligands: ADP, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q9L422_NOSS1 Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed P(II) proteins are highly conserved signal transducers in bacteria, archaea, and plants. They have a large flexible loop (T-loop) that adopts different conformations after covalent modification or binding to different effectors to regulate the functions of diverse protein partners. The P(II) partner PipX (P(II)interaction protein X), first identified from Synechococcus sp. PCC 7942, exists uniquely in cyanobacteria. PipX also interacts with the cyanobacterial global nitrogen regulator NtcA. The mutually exclusive binding of P(II) and NtcA by PipX in a 2-oxoglutarate (2-OG)-dependent manner enables P(II) to indirectly regulate the transcriptional activity of NtcA. However, the structural basis for these exclusive interactions remains unknown. We solved the crystal structure of the P(II)-PipX complex from the filamentous cyanobacterium Anabaena sp. PCC 7120 at 1.90 A resolution. A homotrimeric P(II) captures three subunits of PipX through the T-loops. Similar to P(II) from Synechococcus, the core structure consists of an antiparallel beta-sheet with four beta-strands and two alpha-helices at the lateral surface. PipX adopts a novel structure composed of five twisted antiparallel beta-strands and two alpha-helices, which is reminiscent of the P(II) structure. The T-loop of each P(II) subunit extends from the core structure as an antenna that is stabilized at the cleft between two PipX monomers via hydrogen bonds. In addition, the interfaces between the beta-sheets of PipX and P(II) core structures partially contribute to complex formation. Comparative structural analysis indicated that PipX and 2-OG share a common binding site that overlaps with the 14 signature residues of cyanobacterial P(II) proteins. Our structure of PipX and the recently solved NtcA structure enabled us to propose a putative model for the NtcA-PipX complex. Taken together, these findings provide structural insights into how P(II) regulates the transcriptional activity of NtcA via PipX upon accumulation of the metabolite 2-OG. Crystal structure of the cyanobacterial signal transduction protein PII in complex with PipX.,Zhao MX, Jiang YL, Xu BY, Chen Y, Zhang CC, Zhou CZ J Mol Biol. 2010 Sep 24;402(3):552-9. Epub 2010 Aug 12. PMID:20708625 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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