Essential role of Pro 74 in stefin B amyloid-fibril formation: dual action of cyclophilin A on the process.
We report that Pro74 in human stefin B is critical for fibril formation and that proline isomerization plays an important role. The stefin B P74S mutant did not fibrillate over the time of observation at 25 degrees C, and it exhibited a prolonged lag phase at 30 degrees C and 37 degrees C. The peptidyl prolyl cis/trans isomerase cyclophilin A, when added to the wild-type protein, exerted two effects: it prolonged the lag phase and increased the yield and length of the fibrils. Addition of the inactive cyclophilin A R55A variant still resulted in a prolonged lag phase but did not mediate the increase of the final fibril yield. These results demonstrate that peptidyl prolyl cis/trans isomerism is rate-limiting in stefin B fibril formation.
Smajlović
Aida
A
Department of Biochemistry, Farmaceutical Faculty, University of Tuzla, Tuzla, Bosnia and Herzegovina.
Berbić
Selma
S
Schiene-Fischer
Cordelia
C
Tusek-Znidaric
Magda
M
Taler
Ajda
A
Jenko-Kokalj
Sasa
S
Turk
Dusan
D
Zerovnik
Eva
E
D000682:Amyloid / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D021984:Cyclophilin A / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D055313:Cystatin B / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009154:Mutation; D011392:Proline / Q000235:genetics / Q000378:metabolism; D020836:Protein Structure, Quaternary / Q000235:genetics; D013997:Time Factors
D000682:Amyloid; C524994:CSTB protein, human; D055313:Cystatin B; D011392:Proline; D021984:Cyclophilin A