Antimicrobial Peptide LL-37 Is Both a Substrate of Cathepsins S and K and a Selective Inhibitor of Cathepsin L

Research output: Contribution to journalResearch articleContributedpeer-review


  • Pierre-Marie Andrault - , Institut national de la santé et de la recherche médicale (First author)
  • Sergey A Samsonov - , Structural Bioinformatics (Research Group), Biotechnology Center (Author)
  • Gunther Weber - , Institut national de la santé et de la recherche médicale (Author)
  • Laurent Coquet - , Plate-forme de Protéomique "PISSARO" de l'IRIB (Author)
  • Kamran Nazmi - , University of Amsterdam, Vrije Universiteit Amsterdam (Author)
  • Jan G M Bolscher - , Vrije Universiteit Amsterdam, University of Amsterdam (Author)
  • Anne-Christine Lalmanach - , National Institute of Agricultural Research (INRAE) (Author)
  • Thierry Jouenne - , Plate-forme de Protéomique "PISSARO" de l'IRIB (Author)
  • Dieter Brömme - , University of British Columbia (Author)
  • M Teresa Pisabarro - , Structural Bioinformatics (Research Group), Biotechnology Center (Author)
  • Gilles Lalmanach - , Institut national de la santé et de la recherche médicale (Author)
  • Fabien Lecaille - , Institut national de la santé et de la recherche médicale (Author)


Lung cysteine cathepsins B, K, L, and S contribute to physiological and pathological processes including degradation of antimicrobial peptides/proteins (AMPs) such as surfactant protein SP-A, lactoferrin, secretory leukocyte peptidase inhibitor, and beta-defensins-2 and -3. Substantial amounts of uncleaved LL-37, a 37-mer cationic AMP, were observed in the sputum of patients with cystic fibrosis (CF). Nevertheless LL-37 was degraded after prolonged incubation in CF sputum, and the hydrolysis was blocked by E-64, a selective inhibitor of cysteine proteases. Cathepsins K and S, expressed in human alveolar macrophages, thoroughly hydrolyzed LL-37 in vitro, whereas it competitively inhibited cathepsin L (Ki = 150 nM). Cleavage of LL-37 by cathepsins S and K impaired its antimicrobial activity against Pseudomonas aeruginosa and Staphylococcus aureus, in a time- and concentration-dependent manner. The exchange of residues 67 and 205 in the S2 pockets of cathepsins L (Leu67Tyr/Ala205Leu) and K (Tyr67Leu/Leu205Ala) switched the specificity of these mutants toward LL-37. Molecular modeling suggested that LL-37 interacted with the active site of cathepsin L in both forward (i.e., substrate-like) and reverse orientations with similar binding energies. Our data support the hypothesis that cysteine cathepsins modulate the innate immunity response by degrading distinct and representative members of the AMP family.


Original languageEnglish
Pages (from-to)2785-98
Number of pages14
Journal Biochemistry : a weekly publication of the American Chemical Society
Issue number17
Publication statusPublished - 5 May 2015

External IDs

Scopus 84928963891



  • Amino Acid Sequence, Antimicrobial Cationic Peptides/chemistry, Bronchoalveolar Lavage Fluid, Cathepsin K/metabolism, Cathepsin L/antagonists & inhibitors, Cathepsins/metabolism, Circular Dichroism, Cysteine Proteinase Inhibitors/metabolism, Cystic Fibrosis/microbiology, Humans, Macrophages, Alveolar/metabolism, Microbial Sensitivity Tests, Molecular Sequence Data, Pseudomonas aeruginosa/drug effects, Substrate Specificity