C-terminal truncation of a bovine B12 trafficking chaperone enhances the sensitivity of the glutathione-regulated thermostability

The human B12 trafficking chaperone hCblC is well conserved inmammals and non-mammalian eukaryotes. However, the C-terminal∼40 amino acids of hCblC vary significantly and arepredicted to be deleted by alternative splicing of the encodinggene. In this study, we examined the thermostability of the bovineCblC truncated at the C-terminal variable region (t-bCblC) and itsregulation by glutathione. t-bCblC is highly thermolabile (Tm =∼42oC) similar to the full-length protein (f-bCblC). However,t-bCblC is stabilized to a greater extent than f-bCblC by binding ofreduced glutathione (GSH) with increased sensitivity to GSH. Inaddition, binding of oxidized glutathione (GSSG) destabilizest-bCblC to a greater extent and with increased sensitivity ascompared to f-bCblC. These results indicate that t-bCblC is a moresensitive form to be regulated by glutathione than the full-lengthform of the protein. [BMB Reports 2013; 46(3): 169-174]