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Modulation of protein-protein interactions by synthetic receptors: design of molecules that disrupt serine protease-proteinaceous inhibitor interaction.

ABSTRACT: In the present article we describe the design and evaluation of a synthetic receptor that binds to the exterior surface of chymotrypsin and disrupts its interaction with proteinaceous inhibitors, such as soybean trypsin inhibitor, basic pancreatic trypsin inhibitor, ovomucoid turkey inhibitor, and Bowman-Birk inhibitor. Using enzyme kinetics, nondenaturing gel electrophoresis, and gel filtration chromatography we show that the receptor is particularly effective at blocking the chymotrypsin-soybean trypsin inhibitor complex and that the mechanism involves formation of an initial ternary complex followed by a time-dependent displacement of the proteinaceous inhibitor.

SUBMITTER: Park HS

PROVIDER: S-EPMC122729 | biostudies-literature | 2002 Apr

REPOSITORIES: biostudies-literature

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Modulation of protein-protein interactions by synthetic receptors: design of molecules that disrupt serine protease-proteinaceous inhibitor interaction.

Park Hyung Soon HS Lin Qing Q Hamilton Andrew D AD

Proceedings of the National Academy of Sciences of the United States of America 20020401 8

In the present article we describe the design and evaluation of a synthetic receptor that binds to the exterior surface of chymotrypsin and disrupts its interaction with proteinaceous inhibitors, such as soybean trypsin inhibitor, basic pancreatic trypsin inhibitor, ovomucoid turkey inhibitor, and Bowman-Birk inhibitor. Using enzyme kinetics, nondenaturing gel electrophoresis, and gel filtration chromatography we show that the receptor is particularly effective at blocking the chymotrypsin-soybe ...[more]

PMID: 11959960

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Project description:BACKGROUND: Proteins belonging to the serine protease inhibitor (serpin) superfamily play essential physiological roles in many organisms. In pathogens, serpins are thought to have evolved specifically to limit host immune responses by interfering with the host immune-stimulatory signals. Serpins are less well characterised in parasitic helminths, although some are thought to be involved in mechanisms associated with host immune modulation. In this study, we cloned and partially characterised a secretory serpin from Schistosoma japonicum termed SjB6, these findings provide the basis for possible functional roles. METHODS: SjB6 gene was identified through database mining of our previously published microarray data, cloned and detailed sequence and structural analysis and comparative modelling carried out using various bioinformatics and proteomics tools. Gene transcriptional profiling was determined by real-time PCR and the expression of native protein determined by immunoblotting. An immunological profile of the recombinant protein produced in insect cells was determined by ELISA. RESULTS: SjB6 contains an open reading frame of 1160 base pairs that encodes a protein of 387 amino acid residues. Detailed sequence analysis, comparative modelling and structural-based alignment revealed that SjB6 contains the essential structural motifs and consensus secondary structures typical of inhibitory serpins. The presence of an N-terminal signal sequence indicated that SjB6 is a secretory protein. Real-time data indicated that SjB6 is expressed exclusively in the intra-mammalian stage of the parasite life cycle with its highest expression levels in the egg stage (p?<?0.0001). The native protein is approximately 60 kDa in size and recombinant SjB6 (rSjB6) was recognised strongly by sera from rats experimentally infected with S. japonicum. CONCLUSIONS: The significantly high expression of SjB6 in schistosome eggs, when compared to other life cycle stages, suggests a possible association with disease pathology, while the strong reactivity of sera from experimentally infected rats against rSjB6 suggests that native SjB6 is released into host tissue and induces an immune response. This study presents a comprehensive demonstration of sequence and structural-based analysis of a secretory serpin from a trematode and suggests SjB6 may be associated with important functional roles in S. japonicum, particularly in parasite modulation of the host microenvironment.

Project description:Proteases facilitate a number of steps in cancer progression. The serine protease inhibitors (serpins) are a protein superfamily with inhibitory activity against proteases. One of these proteases, serpinA3, appears to have a multifaceted role and is associated with inflammatory reactions, Alzheimer's disease, malignant melanoma and gastric cancer. To gain insight into the potential effect of serpinA3 on colorectal cancer (CRC) we determined whether serpinA3 is altered in colorectal tissue or plasma in CRC patients. Collectively, by using ELISA we noted a significantly lower serpinA3 level in cancer tissue compared to paired normal tissue. Moreover, the tumour serpinA3 level tended to be higher in disseminated disease as compared to localised disease. No significant difference in the plasma levels of serpinA3 was noted in the patients when compared to the controls. However, plasma serpinA3 and C-reactive protein (marker of inflammation) in the CRC patients and controls were significantly positively correlated. To confirm and detect localization of serpinA3 expression, immunohistochemistry was performed. Immunohistochemistry showed heterogeneous immunoreactivity in epithelial cells in the cancer and normal tissue and extracellular staining within bands of stroma as well as in some stromal cells. A Taq Man system was used to investigate a single nucleotide polymorphism (rs4934) in the serpinA3 signal sequence gene with supposed effect on serpinA3 secretion and expression. No significant difference was observed between CRC and control subjects regarding genotype and allelic distributions, nor were associations noted between clinical characteristics and serpinA3 levels. In conclusion, an altered serpinA3 concentration in CRC tissue may be a potential biomarker in CRC progression. SerpinA3 concentrations in plasma appear to be correlated with systemic inflammation, but do not appear to be specific to CRC patients. Further studies are warranted to improve our understanding of the role of serpinA3 in CRC.

Dataset Information

Modulation of protein-protein interactions by synthetic receptors: design of molecules that disrupt serine protease-proteinaceous inhibitor interaction.

Publications

Modulation of protein-protein interactions by synthetic receptors: design of molecules that disrupt serine protease-proteinaceous inhibitor interaction.

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