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Updated: Feb 15, 2026

Fluorescence Assays for the Study of Mycobacterium tuberculosis Interaction with the Immune Receptor SLAMF1
Published on: February 28, 2025
The Biological Properties and Potential Interacting Proteins of d-Alanyl-d-alanine Ligase A from Mycobacterium
Shufeng Yang1, Yuefei Xu1, Yan Wang1
1Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, China. shufengyang78@163.com.
Abstract:
(1) Background: d-alanine-d-alanine ligase (DdlA), an effective target for drug development to combat against Mycobacterium tuberculosis (Mtb), which threatens human health globally, supplies a substrate of d-alanyl-d-alanine for peptidoglycan crosslinking by catalyzing the dimerization of two d-alanines. To obtain a better understanding of DdlA profiles and develop a colorimetric assay for high-throughput inhibitor screening, we focused on explicating and characterizing Tb-DdlA. (2) Methods and Results: Rv2981c (ddlA) was expressed in Escherichia coli, and the purified Tb-DdlA was identified using (anti)-polyhistidine antibody followed by DdlA activity confirmation by measuring the released orthophosphate via colorimetric assay and the yielded d-alanyl-d-alanine through high performance thin layer chromatography (HP-TLC). The kinetic assays on Tb-DdlA indicated that Tb-DdlA exhibited a higher affinity to ATP (KmATP: 50.327 ± 4.652 μmol/L) than alanine (KmAla: 1.011 ± 0.094 mmol/L). A colorimetric assay for Tb-DdlA activity was developed for high-throughput screening of DdlA inhibitors in this study. In addition, we presented an analysis on Tb-DdlA interaction partners by pull-down assay and MS/MS. Eight putative interaction partners of Tb-DdlA were identified. (3) Conclusions: Our dataset provided a valuable resource for exploring Tb-DdlA biology, and developed an easy colorimetric assay for screening of Tb-DdlA inhibitors.
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