Open AccessAn Internal FK506‐Binding Domain is the Catalytic Core of the Prolyl Isomerase Activity Associated with the Bacillus Subtilis Trigger Factor
Author(s) -
Göthel Sven F.,
Schmid Roland,
Wipat Anil,
Carter Noel M.,
Emmerson Peter T.,
Harwood Colin R.,
Marahiel Mohamed A.
Publication year - 1997
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1997.00059.x
Subject(s) - peptidylprolyl isomerase , bacillus subtilis , prolyl isomerase , cyclophilin , isomerase , biology , biochemistry , fkbp , gene , mutant , protein disulfide isomerase , cyclophilin a , cis trans isomerases , microbiology and biotechnology , enzyme , genetics , pin1 , bacteria
Two major families of peptidylprolyl cis‐ trans ‐isomerases, the cyclophilins and the structurally unrelated FK506‐binding proteins (FKBPs), have been identified as cellular factors involved in protein folding in vitro. Here we report on the biochemical characterization of a second prolyl isomerase of Bacillus subtilis that was purified from a cyclophilin‐negative ( ppiB null) mutant and was shown to be the trigger factor (TigBS). N‐terminal sequencing of 27 amino acid residues of the purified protein revealed 100% identity to the deduced sequence encoded by the tig gene, sequenced as a part of the B. subtilis genome project. The tigBS gene, located at 246° on the genetic map upstream of the clpX and lonA, B genes, encodes an acidic protein (pI 4.3) of 47.5 kDa. Purified and recombinant TigBS‐His proteins share the same substrate specificity and catalytic activity ( k cat / K m of 1.5 μM −1 s −1 ); both are inhibited by the macrolide FK506 with IC 50 the range of 500 nM. We also demonstrate that the prolyl isomerase activity of TigBS is mediated by an internal domain of about 13 kDa (homologous to FKPB12) that represents the catalytic core of the trigger factor.