Two distinct forms of peptidylprolyl-cis-trans-isomerase are expressed separately in periplasmic and cytoplasmic compartments of Escherichia coli cells

Abstract

Peptidylprolyl-cis-trans-isomerase (PPIase) is thought to be essential for protein folding in the cell. Two forms, a and b, of PPIase and their corresponding genes were isolated from Escherichia coli cells. Despite their insensitivity to cyclosporin A (CsA), both amino acid sequences were homologous and related to that of pig cyclophilin, a protein that has PPIase activity sensitive to CsA (Takahashi et al., 1989). PPIase a is found to be identical with the E. coli ORF 190 gene product that was sequenced by Kawamukai et al. (1989) and overexpressed by Liu and Walsh (1990). It is translocated into E. coli periplasmic space with the signal sequence. PPIase b lacks a hydrophobic amino acid stretch which could serve as a signal sequence or a transmembrane domain, and it is detected mainly in the bacterial cytoplasm. These findings indicate that proteins with the ability to assist folding of various polypeptides are located on both sides of the inner membrane. Thus, we propose that the folding of some exported proteins may be catalyzed by the periplasmic proline isomerase and, in turn, that some proteins which have isomerized may not be translocated efficiently.

Active site mutants of human cyclophilin A separate peptidyl‐prolyl isomerase activity from cyclosporin A binding and calcineurin inhibition

“…However, these values for k,,,/K,,, in Table l are above nonenzymatic background levels. It should also be noted that the residual activity may be due to contamination by endogenous E. coli CyPs Hayano et al, 1991); therefore, these three mutants may be even less active than the data in Table 1 indicate. A further point emerges when one examines the ability of CsA to bind to R55A, F60A, or H126Q mutants. Because of the low residual activity (and the possibility of endogenous E. coli CyP contamination), K; measurement was not possible with the assay used.…”

Native Recombinant Cyclophilins A, B, and C Degrade DNA Independently of Peptidylprolyl cis-trans-Isomerase Activity

“…Cyps range in size from 15 to 40 kDa (1)(2)(3). This large family of proteins has been isolated from a diverse range of organisms, including Neurospora (4), Escherichia coli (5,6), yeast (7), plants, and higher eukaryotes (7,8). Cyps have been identified in every tissue studied in humans (7,8) and have been localized to the cytoplasm (1), mitochondria (9), nucleus (8,10), and endoplasmic reticulum (11) in various mammalian cells and the cytoplasm and periplasm (5,12) in E. coli.…”

Proline 21, a residue within the α‐helical domain of ΦX174 lysis protein E, is required for its function in Escherichia coli

“…In contrast to strict FKBP domains, not all residues needed for FK506 binding are possessed within the FKBP-like domain (Callebaut and Mornon, 1995). To determine whether the activity of a peptidylprolyl cis-trans isomerase (rotamase) can explain the results described above, we attempted to complement the slyD mutation with genes for other known rotamases: rotA (periplasmatic) and rotB (cytoplasmatic) (Hayano et al, 1991). As shown in Fig.…”