Open AccessMycoplasma pneumoniae Mpn133 is a cytotoxic nuclease with a glutamic acid‐, lysine‐ and serine‐rich region essential for binding and internalization but not enzymatic activity
Author(s) -
Somarajan Sudha R.,
Kannan Thirumalai R.,
Baseman Joel B.
Publication year - 2010
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2010.01513.x
Subject(s) - biology , internalization , nuclease , amino acid , cytotoxic t cell , biochemistry , microbiology and biotechnology , enzyme , cell , in vitro
Summary We identified Mpn133 as a Ca 2+ ‐dependent cytotoxic nuclease of Mycoplasma pneumoniae . Flow cytometry analysis and immunofluorescence studies revealed the binding and internalization of recombinant Mpn133 (rMpn133) in human airway A549 cells. Amino acid sequence comparisons of Mpn133 with other mycoplasma nucleases demonstrated the presence of a unique glutamic acid‐, lysine‐ and serine‐rich region (EKS region; amino acids 72–110). Deletion of this EKS peptide (rMpn133 Δ72–110 ) abrogated its binding and internalization but not its nuclease activity. The function of the EKS region in host cell trafficking and nuclear localization was reinforced by the successful delivery of EKS‐conjugated mCherry protein into A549 cells. rMpn133, but not rMpn133 Δ72–110 , induced apoptosis‐like death in A549 cells. This observation suggested a unique role of Mpn133 as an important contributor to M. pneumoniae ‐associated life cycle events and as a virulence factor in host‐associated cytopathologies. In addition, the distinct property of the EKS peptide in delivery of proteins, like mCherry, into target cells opens new avenues to the establishment of novel concepts of drug delivery and therapy.