Manganese Binding to the Prion Protein

Abstract

There is considerable evidence that the prion protein binds copper. However, there have also been suggestions that prion protein (PrP) binds manganese. We used isothermal titration calorimetry to identify the manganese binding sites in wild-type mouse PrP. The protein showed two manganese binding sites with affinities that would bind manganese at concentrations of 63 and 200 M at pH 5.5. This indicates that PrP binds manganese with affinity similar to other known manganese-binding proteins. Further study indicated that the main manganese binding site is associated with His-95 in the so-called "fifth site" normally associated with copper binding. Additionally, it was shown that occupancy by copper does not prevent manganese binding. Under these conditions, manganese binding resulted in an altered conformation of PrP, displacement of copper, and altered redox chemistry of the metal-protein complex. Cyclic voltammetric measurements suggested a complex redox chemistry involving manganese bound to PrP, whereas copper-bound PrP was able to undergo fully reversible electron cycling. Additionally, manganese binding to PrP converted it to a form able to catalyze aggregation of metal-free PrP. These results further support the notion that manganese binding could cause a conformation change in PrP and trigger changes in the protein similar to those associated with prion disease.

Mutational and Metal Binding Analysis of the Endonuclease Domain of the Influenza Virus Polymerase PA Subunit

“…4C and E). The measured affinities lie in the range of those obtained for other divalent cation binding proteins, such as RNAses and proteases (3,20,36). The fact that the binding enthalpy is exothermic for Mn 2ϩ ions and endothermic for Mg 2ϩ ions suggests a more optimal coordination for bound Mn 2ϩ ions, which is reflected in a more favorable enthalpy.…”

Iron, Aging, and Neurodegeneration

“…The latter was somewhat unexpected and remains controversial. While copper has been associated with normal PrP c activities, the data suggest that manganese binds to PrP c in disease and can cause its conformational change [127,128]. Manganese binding to PrP also increases its survival in the environment and increases its ability to cause prion infection in cells [129].…”

Involvement of Neuroinflammation during Brain Development in Social Cognitive Deficits in Autism Spectrum Disorder and Schizophrenia

“…The treatment of cuprizone in mice is thought to be useful as a model of prion infection because of the involvement of metal homeostasis in functions of a cellular prion protein (PrPC) (Martins et al, 2001). PrPC is predominately expressed in neuronal cells (Ramasamy et al, 2003) and can bind copper, zinc, iron, and manganese (Brazier et al, 2008;Davies et al, 2009). Interestingly, manganese can induce prion protein transformation from PrPC to a disease-associated isoform (PrPSc) (Brazier et al, 2008).…”

“…PrPC is predominately expressed in neuronal cells (Ramasamy et al, 2003) and can bind copper, zinc, iron, and manganese (Brazier et al, 2008;Davies et al, 2009). Interestingly, manganese can induce prion protein transformation from PrPC to a disease-associated isoform (PrPSc) (Brazier et al, 2008). Furthermore, PrPC but not PrPSc has SOD-1 activity, Fig.…”