Streptococcus pneumoniae ClpL modulates adherence to A549 human lung cells through Rap1/Rac1 activation

Cuong Thach Nguyen, Nhat-Tu Le, Thao Dang-Hien Tran, Eun-Hye Kim, Sang-Sang Park, Truc Thanh Luong, Kyung-Tae Chung, Suhkneung Pyo, Dong-Kwon Rhee

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Caseinolytic protease L (ClpL) is a member of the HSP100/Clp chaperone family, which is found mainly in Gram-positive bacteria. ClpL is highly expressed during infection for refolding of stress-induced denatured proteins, some of which are important for adherence. However, the role of ClpL in modulating pneumococcal virulence is poorly understood. Here, we show that ClpL impairs pneumococcal adherence to A549 lung cells by inducing and activating Rap1 and Rac1, thus increasing phosphorylation of cofilin (inactive form). Moreover, infection with a clpL mutant (ΔclpL) causes a greater degree of filopodium formation than D39 wild-type (WT) infection. Inhibition of Rap1 and Rac1 impairs filopodium formation and pneumococcal adherence. Therefore, ClpL can reduce pneumococcal adherence to A549 cells, likely via modulation of Rap1- and Rac1-mediated filopodium formation. These results demonstrate a potential role for ClpL in pneumococcal resistance to host cell adherence during infection. This study provides insight into further understanding the interactions between hosts and pathogens.

Original languageEnglish (US)
Pages (from-to)3802-10
Number of pages9
JournalInfection and Immunity
Issue number9
StatePublished - Sep 2014


  • Actin Depolymerizing Factors
  • Actins
  • Bacterial Adhesion
  • Bacterial Proteins
  • Cell Line, Tumor
  • Endopeptidase Clp
  • Humans
  • Lung Neoplasms
  • Pneumococcal Infections
  • Serine Endopeptidases
  • Streptococcus pneumoniae
  • Telomere-Binding Proteins
  • Virulence
  • rac1 GTP-Binding Protein
  • Journal Article
  • Research Support, Non-U.S. Gov't


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