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.
Plant Biochemistry Laboratory, Biological Research Institute, National Scientific and Technical Research Council, University of Mar del Plata, Mar del Plata 7600, Argentina.
Fernando F
FF
Muñoz
Julieta R
JR
Mendieta
Mariana R
MR
Pagano
Roberto A
RA
Paggi
Gustavo R
GR
Daleo
María G
MG
Guevara
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