Activity of a Two-Domain Antifreeze Protein Is Not Dependent on Linker Sequence

ABSTRACT

The reported NMR structure of RD3, a naturally occurring two-domain antifreeze protein, suggests that the two nearly identical domains are oriented to allow simultaneous binding of their active regions to the ice surface. It is implied that the nine residues linking the two domains play a role in this alignment, but this has not been established. We have designed and expressed a modified form of RD3 that replaces the nine-residue linker with a generic sequence of one serine and eight glycine residues to test the importance of the linker amino acid sequence. The modified linker is shown to have significantly different characteristics compared to the original linker. …