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bioRxiv · 10.64898/2026.03.19.713020

A DltE-DltD-DltX interaction network regulates lipoteichoic acid D-alanylation in Lactiplantibacillus plantarum and symbiotic drosophila growth promotion

Matos, R. C.·Nikolopoulos, N.·Perrier, Q.·Robert, X.·Gueguen-Chaignon, V.·Hirayama, H.·Leulier, F.·Grangeasse, C.·Guerardel, Y.·Ravaud, S.
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Abstract

D-alanylation of teichoic acids is a widespread modification of Gram-positive bacterial cell envelopes that modulates resistance to environmental stresses and host interactions. Although the cytosolic steps of this pathway are well characterized, the extracellular reactions responsible for transferring D-alanine onto teichoic acids remain poorly understood. Here we investigate the role of DltD in the commensal bacterium Lactiplantibacillus plantarum. We determined the 2.3 [A] crystal structure of the extracellular catalytic domain of DltD, which adopts an SGNH-hydrolase fold with a conserved Ser-His-Asp catalytic triad. Docking analyses with lipoteichoic acids (LTA) fragments suggest that the glycerol-phosphate backbone of LTA is accommodated along a surface groove leading to the catalytic serine, with conserved residues contributing to substrate positioning. Biochemical measurements further reveal direct interactions between DltD, the acyl-carrier protein DltX, and the LTA esterase DltE. The conserved C-terminal motif of DltX binds DltD and is required for efficient D-alanylation and for L. plantarum-mediated promotion of Drosophila juvenile growth. Together, these findings support a DltX-dependent acyl-transfer mechanism and reveal an interaction network that coordinates LTA D-alanylation in a symbiotic bacterium.

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Matos, R. C., Nikolopoulos, N., Perrier, Q., Robert, X., Gueguen-Chaignon, V., Hirayama, H., Leulier, F., Grangeasse, C., Guerardel, Y., Ravaud, S.. 2026-03-20. A DltE-DltD-DltX interaction network regulates lipoteichoic acid D-alanylation in Lactiplantibacillus plantarum and symbiotic drosophila growth promotion. https://doi.org/10.64898/2026.03.19.713020

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