5tu9

Crystal structure of Staphylococcus epidermidis Aap G58-spacer-G513 (variant G5-spacer-consensus G5)

spinqualitylabelsall models 5tu9, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5tu9 is a 2 chain structure with sequence from Staeq. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 5tu7, 5tu8 Gene: aap, SERP2398 (STAEQ) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Staphylococcus epidermidis is an opportunistic pathogen that can form robust biofilms that render the bacteria resistant to antibiotic action and immune responses. Intercellular adhesion in S. epidermidis biofilms is mediated by the cell wall-associated Accumulation-Associated Protein (Aap), via zinc-mediated self-assembly of its B-repeat region. This region contains up to 17 nearly-identical sequence repeats, with each repeat assumed to be functionally equivalent. However, Aap B-repeats exist as two subtypes, defined by a cluster of consensus or variant amino acids. These variable residues are positioned near the zinc-binding (and dimerization) site and the stability determinant for the B-repeat fold. We have characterized four B-repeat constructs to assess the functional relevance of the two Aap B-repeat subtypes. Analytical ultracentrifugation experiments demonstrated that constructs with the variant sequence show reduced or absent Zn2+-induced dimerization. Likewise, circular dichroism thermal denaturation experiments showed that the variant sequence could significantly stabilize the fold, depending on its location within the construct. Crystal structures of three of the constructs revealed that the side chains from the variant sequence form an extensive bonding network that can stabilize the fold. Furthermore, altered distribution of charged residues between consensus and variant sequences changes the electrostatic potential in the vicinity of the Zn2+ binding site, providing a mechanistic explanation for the loss of zinc-induced dimerization in the variant constructs. These data suggest an assembly code that defines preferred oligomerization modes of the B-repeat region of Aap and a slip-grip model for initial contact and firm intercellular adhesion during biofilm formation. Functional consequences of B-repeat sequence variation in the Staphylococcal biofilm protein Aap: Deciphering the assembly code.,Shelton CL, Conrady DG, Herr AB Biochem J. 2016 Nov 21. pii: BCJ20160675. PMID:27872164 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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