4aeq

Crystal structure of the dimeric immunity protein Cmi solved by direct methods (Arcimboldo)

spinqualitylabelsall models 4aeq, resolution 1.89Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4aeq is a 1 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: PO4 Related: 2xgl Resources: FirstGlance, OCA, RCSB, PDBsum Function [IMMM_ECOLX] This protein is able to protect a cell, which harbors the plasmid ColBM-Cl139 encoding colicin M, against colicin M. Publication Abstract from PubMed Bacteriocins are proteins secreted by many bacterial cells to kill related bacteria of the same niche. To avoid their own suicide through reuptake of secreted bacteriocins, these bacteria protect themselves by co-expression of immunity proteins in the compartment of colicin destination. In Escherichia coli the colicin M (Cma) is inactivated by the interaction with the Cma immunity protein (Cmi). We have crystallized and solved the structure of Cmi at a resolution of 1.95A by the recently developed ab initio phasing program ARCIMBOLDO. The monomeric structure of the mature 10kDa protein comprises a long N-terminal alpha-helix and a four-stranded C-terminal beta-sheet. Dimerization of this fold is mediated by an extended interface of hydrogen bond interactions between the alpha-helix and the four-stranded beta-sheet of the symmetry related molecule. Two intermolecular disulfide bridges covalently connect this dimer to further lock this complex. The Cmi protein resembles an example of a 3D domain swapping being stalled through physical linkage. The dimer is a highly charged complex with a significant surplus of negative charges presumably responsible for interactions with Cma. Dimerization of Cmi was also demonstrated to occur in vivo. Although the Cmi-Cma complex is unique among bacteria, the general fold of Cmi is representative for a class of YebF-like proteins which are known to be secreted into the external medium by some Gram-negative bacteria. The crystal structure of the dimeric colicin M immunity protein displays a 3D domain swap.,Uson I, Patzer SI, Rodriguez DD, Braun V, Zeth K J Struct Biol. 2012 Apr;178(1):45-53. Epub 2012 Feb 16. PMID:22366279 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Colicin Immunity Protein

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