The swaposin-like domain of potato aspartic protease (StAsp-PSI) exerts antimicrobial activity on plant and human pathogens.
Plant-specific insert domain (PSI) is a region of approximately 100 amino acid residues present in most plant aspartic protease (AP) precursors. PSI is not a true saposin domain; it is the exchange of the N- and C-terminal portions of the saposin like domain. Hence, PSI is called a swaposin domain. Here, we report the cloned, heterologous expression and purification of PSI from StAsp 1 (Solanum tuberosum aspartic protease 1), called StAsp-PSI. Results obtained here show that StAsp-PSI is able to kill spores of two potato pathogens in a dose-dependent manner without any deleterious effect on plant cells. As reported for StAPs (S. tuberosum aspartic proteases), the StAsp-PSI ability to kill microbial pathogens is dependent on the direct interaction of the protein with the microbial cell wall/or membrane, leading to increased permeability and lysis. Additionally, we demonstrated that, like proteins of the SAPLIP family, StAsp-PSI and StAPs are cytotoxic to Gram-negative and Gram-positive bacteria in a dose dependent manner. The amino acid residues conserved in SP_B (pulmonary surfactant protein B) and StAsp-PSI could explain the cytotoxic activity exerted by StAsp-PSI and StAPs against Gram-positive bacteria. These results and data previously reported suggest that the presence of the PSI domain in mature StAPs could be related to their antimicrobial activity.
Muñoz
Fernando F
FF
Plant Biochemistry Laboratory, Biological Research Institute, National Scientific and Technical Research Council, University of Mar del Plata, Mar del Plata 7600, Argentina.
Mendieta
Julieta R
JR
Pagano
Mariana R
MR
Paggi
Roberto A
RA
Daleo
Gustavo R
GR
Guevara
María G
MG
D000890:Anti-Infective Agents / Q000009:adverse effects / Q000378:metabolism / Q000494:pharmacology*; D057055:Aspartic Acid Proteases / Q000009:adverse effects / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D001409:Bacillus cereus / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D005670:Fusarium / Q000187:drug effects; D006801:Humans; D015151:Immunoblotting; D010838:Phytophthora / Q000187:drug effects; D055750:Phytophthora infestans / Q000187:drug effects; D010940:Plant Proteins / Q000009:adverse effects / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000009:adverse effects / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D011198:Solanum tuberosum / Q000201:enzymology* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects; D014026:Nicotiana / Q000166:cytology / Q000187:drug effects
D000890:Anti-Infective Agents; D010940:Plant Proteins; D011994:Recombinant Proteins; D057055:Aspartic Acid Proteases