Characterization of d-boroAla as a novel broad-spectrum antibacterial agent targeting d-Ala-d-Ala ligase

Sandeep Putty, Aman Rai, Darshan Jamindar, Paul Pagano, Cheryl L. Quinn, Takehiko Mima, Herbert P. Schweizer, William G. Gutheil

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


d-boroAla was previously characterized as an inhibitor of bacterial alanine racemase and d-Ala-d-Ala ligase enzymes (Biochemistry, 28, 1989, 3541). In this study, d-boroAla was identified and characterized as an antibacterial agent. d-boroAla has activity against both Gram-positive and Gram-negative organisms, with minimal inhibitory concentrations down to 8μg/mL. A structure-function study on the alkyl side chain (NH 2-CHR-B(OR') 2) revealed that d-boroAla is the most effective agent in a series including boroGly, d-boroHomoAla, and d-boroVal. l-boroAla was much less active, and N-acetylation completely abolished activity. An LC-MS/MS assay was used to demonstrate that d-boroAla exerts its antibacterial activity by inhibition of d-Ala-d-Ala ligase. d-boroAla is bactericidal at 1× minimal inhibitory concentration against Staphylococcus aureus and Bacillus subtilis, which each encode one copy of d-Ala-d-Ala ligase, and at 4× minimal inhibitory concentration against Escherichia coli and Salmonella enterica serovar Typhimurium, which each encode two copies of d-Ala-d-Ala ligase. d-boroAla demonstrated a frequency of resistance of 8×10 -8 at 4× minimal inhibitory concentration in S. aureus. These results demonstrate that d-boroAla has promising antibacterial activity and could serve as the lead agent in a new class of d-Ala-d-Ala ligase targeted antibacterial agents. This study also demonstrates d-boroAla as a possible probe for d-Ala-d-Ala ligase function.

Original languageEnglish (US)
Pages (from-to)757-763
Number of pages7
JournalChemical Biology and Drug Design
Issue number5
StatePublished - Nov 2011
Externally publishedYes


  • Alanine branch
  • Antibacterial
  • Broad spectrum
  • Cell wall
  • d-Ala-d-Ala ligase

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Pharmacology
  • Drug Discovery
  • Organic Chemistry


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