EC:3.4.21.64 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.64 (proteinase K)
4,071 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transmissible mink encephalopathy (TME) has been transmitted to Syrian golden hamsters, and two strains of the causative agent, HYPER (HY) and DROWSY (DY), have been identified that have different biological properties. During scrapie, a TME-like disease, an endogenous cellular protein, the prion protein (PrPC), is modified (to PrPSc) and accumulates in the brain. PrPSc is partially resistant to proteases and is claimed to be an essential component of the infectious agent. Purification and analysis of PrP from hamsters infected with the HY and DY TME agent strains revealed differences in properties of PrPTME sedimentation in N-lauroylsarcosine, sensitivity to digestion with proteinase K, and migration in polyacrylamide gels. PrPC and HY PrPTME can be distinguished on the basis of their relative solubilities in detergent and protease sensitivities. PrPTME from DY-infected brain tissue shared solubility characteristics of PrP from both uninfected and HY-infected tissue. Limited protease digestion of PrPTME revealed strain-specific migration patterns upon polyacrylamide gel electrophoresis. Prolonged proteinase K treatment or N-linked deglycosylation of PrPTME did not eliminate such differences but demonstrated the PrPTME from DY-infected brain was more sensitive to protease digestion than HY PrPTME. Antigenic mapping of PrPTME with antibodies raised against synthetic peptides revealed strain-specific differences in immunoreactivity in a region of the amino-terminal end of PrPTME containing amino acid residues 89 to 103. These findings indicate that PrPTME from the two agent strains, although originating from the same host, differ in composition, conformation, or both. We conclude that PrPTME from the HY and DY strains undergo different posttranslational modifications that could explain differences in the biochemical properties of PrPTME from the two sources. Whether these strain-specific posttranslational events are directly responsible for the distinct biological properties of the HY and DY agent strains remains to be determined.
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PMID:Biochemical and physical properties of the prion protein from two strains of the transmissible mink encephalopathy agent. 134 95

One of the main characteristics of the transmissible isoform of the prion protein (PrP(Sc)) is its partial resistance to proteinase K (PK) digestion. Diagnosis of prion disease typically relies upon immunodetection of PK-digested PrP(Sc) following Western blot or ELISA. More recently, researchers determined that there is a sizeable fraction of PrP(Sc) that is sensitive to PK hydrolysis (sPrP(Sc)). Our group has previously reported a method to isolate this fraction by centrifugation and showed that it has protein misfolding cyclic amplification (PMCA) converting activity. We compared the infectivity of the sPrP(Sc) versus the PK-resistant (rPrP(Sc)) fractions of PrP(Sc) and analyzed the biochemical characteristics of these fractions under conditions of limited proteolysis. Our results show that sPrP(Sc) and rPrP(Sc) fractions have comparable degrees of infectivity and that although they contain different sized multimers, these multimers share similar structural properties. Furthermore, the PK-sensitive fractions of two hamster strains, 263K and Drowsy (Dy), showed strain-dependent differences in the ratios of the sPrP(Sc) to the rPrP(Sc) forms of PrP(Sc). Although the sPrP(Sc) and rPrP(Sc) fractions have different resistance to PK-digestion, and have previously been shown to sediment differently, and have a different distribution of multimers, they share a common structure and phenotype.
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PMID:PK-sensitive PrP is infectious and shares basic structural features with PK-resistant PrP. 2239 43

Prions can persist in the environment for extended periods of time after adsorption to surfaces, including soils, feeding troughs, or fences. Prion strain- and soil-specific differences in prion adsorption, infectivity, and response to inactivation may be involved in strain maintenance or emergence of new strains in a population. Extensive proteinase K (PK) digestion of Hyper (HY) and Drowsy (DY) PrP^Sc resulted in a greater reduction in the level of DY PrP^Sc than of HY PrP^Sc Use of the PK-digested material in protein misfolding cyclic amplification strain interference (PMCAsi) resulted in earlier emergence of HY PrP^Sc than of undigested controls. This result established that strain-specific alteration of the starting ratios of conversion-competent HY and DY PrP^Sc can alter strain emergence. We next investigated whether environmentally relevant factors such as surface binding and weathering could alter strain emergence. Adsorption of HY and DY PrP^Sc to silty clay loam (SCL), both separately and combined, resulted in DY interfering with the emergence of HY in PMCAsi in a manner similar to that seen with unbound controls. Similarly, repeated cycles of wetting and drying of SCL-bound HY and DY PrP^Sc did not alter the emergence of HY PrP^Sc compared to untreated controls. Importantly, these data indicate that prion strain interference can occur when prions are bound to surfaces. Interestingly, we found that drying of adsorbed brain homogenate on SCL could restore its ability to interfere with the emergence of HY, suggesting a novel strain interference mechanism. Overall, these data provide evidence that the emergence of a strain from a mixture can be influenced by nonhost factors.IMPORTANCE The prion strain, surface type, and matrix containing PrP^Sc can influence PrP^Sc surface adsorption. The cumulative effect of these factors can result in strain- and soil-specific differences in prion bioavailability. Environmental weathering processes can result in decreases in PrP^Sc conversion efficiency and infectivity. Little is known about how incomplete inactivation of surface-bound PrP^Sc affects transmission and prion strain emergence. Here, we show that strain interference occurs with soil-bound prions and that altering the ratios of prion strains by strain-specific inactivation can affect strain emergence. Additionally, we identify a novel mechanism of inhibition of prion conversion by environmental treatment-induced changes at the soil-protein interface altering strain emergence. These novel findings suggest that environmental factors can influence strain emergence of surface-bound prions.
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PMID:Alteration of Prion Strain Emergence by Nonhost Factors. 3159 19