Abstract
Protease inhibitors, such as trypsin inhibitor, serum alpha-1 antitrypsin, or liver aprotinin, are a class of proteins that competitively bind and block the catalytic activity of proteolytic enzymes with wide ranging biological functions. A significant number of protease inhibitors have also been shown to possess antimicrobial activity, presumed to contribute in defense against pathogenic microorganisms as plants with higher levels of protease inhibitors tend to exhibit increased resistance towards pathogens. Two proposed mechanisms for the antimicrobial activity are combating microbial proteases that play roles in disease development and disruption of microbial cell wall & membrane necessary for survival. Here we show for the first time a novel activity of soybean trypsin inhibitor and bovine aprotinin that they nick supercoiled, circular plasmid DNA. A number of experiments conducted to demonstrate the observed DNA nicking activity is inherent, rather than a co-purified, contaminating nuclease. The nicking of the plasmid results in markedly reduced efficiencies in transformation of E. coli and transfection of HEK293T cells. Thus, this work reveals yet a new mechanism for the antimicrobial activity by protease inhibitors.
Highlights
Pathogens are known to produce extracellular proteinases which are considered to play roles in disease development
Plasmid DNA nicking by Soybean Trypsin Inhibitor (STI)
Increasing NaCl concentration in the reaction mixture, reduced its accumulation down to 0.6 fold in 0.9 M NaCl (Fig. 1C) - suggesting an interaction between STI and plasmid DNA was required for appearance of the slower migrating band and the interaction was disrupted at higher ionic strength
Summary
Pathogens are known to produce extracellular proteinases which are considered to play roles in disease development. AM activity of proteinase inhibitors (PI) may be a consequence of combating these proteinases in pathogens[1,18]. Accumulation in response to mechanical wounding[23] or UV-radiation[24], arguing against countering pathogenic proteases as the sole mechanism for AM activity. Laboratory of Biochemistry, Northwest Missouri State University, 7314 N. We reveal for the first time a novel activity of soybean trypsin inhibitor and bovine aprotinin as nicking plasmid DNA and reducing its efficiency. This may provide yet a new mechanism for AM activity by PIs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
