Structural basis for the broad specificity of a new family of amino-acid racemases

Espaillat, A.; Carrasco-Lopez, C.; Bernardo-Garcia, N.; Pietrosemoli, N.; Otero, L.H.; Alvarez, L.; de Pedro, M.A.; Pazos, F.; Davis, B.M.; Waldor, M.K.; Hermoso, J.A.; Cava, F.

doi:10.1107/S1399004713024838

Figure 4
The identification of 16 residues that constitute the molecular footprint for BsrV multispecificity and experimental validation. (a) Tree of BsrV orthologues obtained through bioinformatic sequence analysis (see §

2). Alr-like enzymes are highlighted in red, Bsr-like enzymes in blue and non-Alr-like, non-Bsr-like enzymes in green; 15 outlier proteins that do not group with any of these families are shown in black. All Bsr-like family members (including BsrV) and a small subset of Alr-like enzymes (including AlrV and Alr_Ec) are listed. (b) Molecular footprint. Sequence composition (displayed as sequence logos) of the specificity-determining positions for Alr/BsrV-like racemases. The specific residues and their positions are listed at the top. (c) Structural analysis of the broad-spectrum racemase from A. hydrophila (Bsr_Ah). A structural superimposition of BsrV with Bsr_Ah is shown on the left. Loop L2 and the α-helix α10 at the entry channel are labelled. The central panel shows a close-up view of the Bsr_Ah catalytic site. Relevant residues and PLP are shown as sticks; water molecules and Cl⁻ ions are shown as red and green spheres, respectively. In the right box, a close-up view of the back-side region (180° rotation view) of Bsr_Ah with the N-terminal insertion in stick representation is shown. Polar interactions between relevant residues of the N-terminal extensions from both monomers are represented as dotted lines. See also Supplementary Fig. S4.

BIOLOGICAL
CRYSTALLOGRAPHY

ISSN: 1399-0047

Volume 70| Part 1| December 2014| Pages 79-90

doi:10.1107/S1399004713024838

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