title: SlyD proteins from different species exhibit high prolyl isomerase and chaperone activities.
abstract: SlyD is a putative folding helper protein from the Escherichia coli cytosol, which consists of an N-terminal prolyl isomerase domain of the FKBP type and a presumably unstructured C-terminal tail. We produced truncated versions without this tail (SlyD) for SlyD from E. coli, as well as for the SlyD orthologues from Yersinia pestis, Treponema pallidum, Pasteurella multocida, and Vibrio cholerae. They are monomeric in solution and unfold reversibly. All SlyD variants catalyze the proline-limited refolding of ribonuclease T1 with very high efficiencies, and the specificity constants (kcat/KM) are equal to approximately 10(6) M(-1) s(-1). These large values originate from the high affinities of the SlyD orthologues for unfolded RCM-T1, which are reflected in low KM values of approximately 1 microM. SlyD also exhibits pronounced chaperone properties. Permanently unfolded proteins bind with high affinity to SlyD and thus inhibit its prolyl isomerase activity. The unfolded protein chains do not need to contain proline residues to be recognized and bound by SlyD. The conservation of prolyl isomerase activity and chaperone properties within the SlyD family suggests that these proteins might act as true folding helpers in the bacterial cytosol. The SlyD proteins are also well suited for biotechnological applications. As fusion partners they facilitate the refolding and increase the solubility of aggregation-prone proteins such as the gp41 ectodomain fragment of HIV-1.
authors.affiliation: Roche Diagnostics GmbH, Nonnenwald 2, D-82377 Penzberg, Germany. christian.scholz@roche.com
authors.forename: Christian
authors.initials: C
authors.lastname: Scholz
authors.forename: Barbara
authors.initials: B
authors.lastname: Eckert
authors.forename: Franz
authors.initials: F
authors.lastname: Hagn
authors.forename: Peter
authors.initials: P
authors.lastname: Schaarschmidt
authors.forename: Jochen
authors.initials: J
authors.lastname: Balbach
authors.forename: Franz Xaver
authors.initials: FX
authors.lastname: Schmid
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000378:metabolism; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D019696:Peptidylprolyl Isomerase / Q000737:chemistry / Q000378:metabolism*; D011392:Proline / Q000737:chemistry / Q000378:metabolism; D006163:Ribonuclease T1 / Q000737:chemistry / Q000378:metabolism; D012995:Solubility; D013379:Substrate Specificity
chemical_list: D029968:Escherichia coli Proteins; D015700:HIV Envelope Protein gp41; D018832:Molecular Chaperones; C085606:SlyD protein, E coli; D011392:Proline; D006163:Ribonuclease T1; D019696:Peptidylprolyl Isomerase