9sxc | pdb_00009sxc

Crystal structure of the Legionella pneumophila effector SidL (Lpg0437) in complex with its metaeffector LegA11 (Lpg0436)

spinqualitylabelsall models 9sxc, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9sxc is a 2 chain structure with sequence from Legionella pneumophila. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.4Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q5ZYD5_LEGPH Publication Abstract from PubMed Legionella pneumophila is an opportunistic human pathogen that causes atypical pneumonia called Legionnaires' Disease. To replicate within host cells, L. pneumophila injects up to 330 effector proteins into the host cytosol via a Dot/Icm type IV secretion system. Several effectors, called metaeffectors, regulate the activity of other effectors within infected host cells through direct protein-protein interactions. LegA11 (AnkJ/Lpg0436) has been identified as a putative metaeffector of SidL (Ceg14/Lpg0437), one of eight L. pneumophila effectors that inhibit host mRNA translation. LegA11 binds and suppresses SidL enzymatic activity, but the molecular basis of this regulation and impact on mRNA translation are unknown. Here, we present the crystal structure of SidL in complex with LegA11 to a resolution of 2.4 A, revealing a high-affinity 1:1 complex with an extensive interaction interface of ~2300 A(2). Using isothermal titration calorimetry, we determined a dissociation constant of 1.8 nM. In vitro translation assays demonstrate that SidL inhibits mRNA translation, and this activity is completely suppressed by LegA11. Mutagenesis of key interface residues in LegA11 disrupts complex formation and abolishes its metaeffector activity, confirming that LegA11 regulates SidL through direct protein-protein interaction. These findings establish LegA11 as a bona fide metaeffector that contributes to suppression of host mRNA translation by L. pneumophila. Crystal structure of the Legionella pneumophila effector SidL (Lpg0437) in complex with its metaeffector LegA11 (Lpg0436).,Machtens DA, Hutchison CA, Stein AM, Eberhage J, Willerding JM, Eschenburg S, Shames SR, Reubold TF bioRxiv [Preprint]. 2025 Oct 23:2025.10.23.683979. doi: , 10.1101/2025.10.23.683979. PMID:41278709 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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