FK506 binding protein 12 differentially accelerates fibril formation of wild type alpha-synuclein and its clinical mutants A30P or A53T

Aggregation of alpha-synuclein (alpha-SYN) plays a key role in Parkinson's disease. We have previously shown that aggregation of alpha-SYN in vitro is accelerated by addition of FK506 binding proteins (FKBP) and that this effect can be counteracted by FK506, a specific inhibitor of these enzymes. In this paper, we investigated in detail the effect of FKBP12 on early aggregation and on fibril formation of wild-type, A53T and A30P alpha-SYN. FKBP12 has a much smaller effect on the fibril formation of these two clinical mutants alpha-SYN. Using an inactive enzyme, we were able to discriminate between catalytic and non-catalytic effects that differentially influence the two processes. A model explaining non-linear concentration dependencies is proposed.