RNA : pseudouridine synthetase Pus1 from Saccharomyces cerevisiae: Oligomerization property and stoichiometry of the complex with yeast tRNA(Phe)

Yeast RNA:pseudouridine synthetase Pus1 catalyzes the formation of pseudour idines in tRNAs. We report here the quaternary structure of purified recomb inant Pus1 in solution. At low concentration, in the absence of tRNA, Pus1 oligomerizes while at high concentration it precipitates. This oligomerizat ion/aggregation can be prevented by addition of dodecyl-beta-D-maltoside or of yeast tRNA(Phe). The detergent does not significantly interfere with su bstrate binding or with activity of Pus1. The stoichiometry of the Pus1/tRN A(Phe) complex is 1/1. We conclude that the detergent covers an hydrophobic region of the RNA binding pocket responsible for Pus1 aggregation. (C) 199 9 Societe francaise de biochimie et biologie moleculaire / Editions scienti fiques et medicales Elsevier SAS.