1. Volume 24, Issue 10, Pages 1729-1741 (October 2016)
Activation by Allostery in Cell-Wall Remodeling by a Modular Membrane-Bound Lytic Transglycosylase from Pseudomonas aeruginosa 
Teresa Domínguez-Gil, Mijoon Lee, Iván Acebrón-Avalos, Kiran V. Mahasenan, Dusan Hesek, David A. Dik, Byungjin Byun, Elena Lastochkin, Jed F. Fisher, Shahriar Mobashery, Juan A. Hermoso 
Structure 
Volume 24, Issue 10, Pages (October 2016)
DOI: /j.str
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2. Structure 2016 24, 1729-1741DOI: (10.1016/j.str.2016.07.019)
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3. Figure 1
Scheme Showing Different Activities for Peptidoglycan-Degrading Enzymes
The sites of reactions are indicated by the same colors designating each activity.
Structure  , DOI: ( /j.str )
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4. Figure 2 The Three-Dimensional Structure of apo MltF
(A) Cartoon depicting the modular arrangement of MltF: signal peptide (SP) with a lipobox, the ABC-transporter module (ABC), the linker, and the catalytic module (CM). The beginning and the ending of each segment are specified by the amino acid positions.
(B) Three-dimensional structure of apo MltF (colored as in A). The catalytic Glu316 is depicted as yellow-capped sticks in the center of the catalytic module.
(C) The active site of MltF is entirely blocked by the specific interactions, as depicted by Connolly surfaces for both models. Right, an expansion of the catalytic site showing the salt bridge interaction between Arg60 and the catalytic Glu316.
Structure  , DOI: ( /j.str )
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5. Figure 3
The Regulatory Module of MltF Showing the Structure of a Closed, but Unoccupied, Conformation of an SBP/ABC-Transporter Module
(A) The two domains of the regulatory module are colored in two shades of green. Right, an expansion of the interface between the domains highlighting the residues involved in inter-domain salt bridge interactions (depicted as capped sticks). This strong network of interactions (Arg50-Glu184, 2.8 Å and 3.1 Å; Arg50-Glu206, 3.6 Å; Asp91-Lys157, 3.4 Å) keep the RM in a closed conformation in the absence of ligand.
(B) A cross-section of the ligand-binding groove of the RM of MltF showing the Poisson-Boltzmann electrostatic-potential surface (color bar range ±5 kT/e). The dimensions of the cavity are labeled. The Tyr266 residue of the linker is located at the bottom of the cavity and is depicted as capped sticks.
(C) The regulatory module of MltF (same view as that of B) with the three muropeptides (1, 2, and 3 as observed in MltF:1, MltF:2, and MltF:3 complexes, respectively) superimposed. Muropeptides are represented as capped sticks and are labeled.
(D) Electron density maps for the peptide stem observed in the different complexes: MltF:3 complex, MltF:2 complex, and MltF:1 complex. Peptide stems are presented as capped sticks and colored in yellow, orange, and purple, respectively. Electron density corresponds to the (2Fo – Fc) feature-enhanced map contoured at 1.0 σ. In all these cases, electron density was observed only for the peptide portion of the ligand.
Structure  , DOI: ( /j.str )
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6. Figure 4
Allosteric Signal Propagation from the RM to the CM upon Muropeptide Binding
(A) Superimposition of the crystal structure of apo MltF (light-brown ribbon) with the crystal structure of MltF:3 complex (green ribbon). The muropeptide is depicted as black capped sticks. Arrows indicate molecular motion in both RM and CM (see also Movie S1).
(B) Superimposition of the crystal structure of apo MltF (black ribbon) with the 12 independent monomers observed in the MltF:3:NAG-NAM-NAG-NAM complex.
(C) Structural comparison between the inactive conformation of MltF (left, this work) and of the fully open conformation for the same enzyme (right; PDB: 4P11). Ribbons are colored as in Figure 2. Both structures have the same orientation for the RM. Activation of the protein involves rotation of 129° and displacements of >55 Å by the CM. The catalytic Glu316 is depicted as capped sticks with its carbon atoms colored in yellow. In the inactive conformation, the linker is present in an extended-coiled conformation spanning 30 Å from Cα of Tyr266 to Cα of Tyr278. In the active conformation, the linker organizes as a helical structure having half (14.5 Å) the original length (see also Movie S2).
Structure  , DOI: ( /j.str )
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7. Figure 5
Reaction of the Crystals of apo MltF with (NAG-NAM)n-NAG-anhNAM in the Absence or Presence of Compound 3
Extracted-ion-chromatograms of the substrate/product mixture obtained with compounds 4 (A), 4 with MltFcrystal (B), 3 + 4 with MltFcrystal (C), compounds 9 (D), 9 with MltFcrystal (E), 3 + 9 with MltFcrystal (F) demonstrate the positive effect of the presence of the muropeptides as effectors of the catalytic transformation of 4 (or 9) as an MltF substrate. Upon activation MltF acts primarily as an endolytic enzyme. 4, n = 2–9; 9, n = 4–8.
Structure  , DOI: ( /j.str )
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8. Figure 6
Muropeptide-Induced Activation of the Catalytic Activity in MltF
(A) Proposed model for the muropeptide-induced activation of the catalytic activity in MltF is depicted as a cartoon (top) and associated crystallographic structures (below). Muropeptides (mp) bound within the RM are depicted as spheres. Asterisk corresponds to the active conformation.
(B) MltF interacts with long PG chains in the middle. Three-dimensional structure of active MltF (PDB: 4P0G) is superimposed with the NMR-based structure (Meroueh et al., 2006) of the cross-linked peptidoglycan (salmon sticks). A structural model for a bilayer lipidic membrane is depicted for comparison purposes.
Structure  , DOI: ( /j.str )
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9. Structure 2016 24, 1729-1741DOI: (10.1016/j.str.2016.07.019)
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