Identification of an atypical peptidyl-prolyl cis/trans isomerase from trypanosomatids

Abstract

The parvulin family of peptidyl-prolyl cis/trans isomerases (PPIases) catalyzes the cis/trans isomerization of the peptide bonds preceding Pro residues. Eukaryotic parvulin-type PPIases have been shown to be involved in cell proliferation and cell cycle progression. Here we present the biochemical and molecular characterization of a novel multi-domain parvulin-type PPIase from the human pathogenic Trypanosoma cruzi, annotated as TcPar45. Like most other parvulins, Par45 has an N-terminal extension, but, in contrast to human Pin1, it contains a forkhead-associated domain (FHA) instead of a WW domain at the N-terminal end. Par45 shows a strong preference for a substrate with the basic Arg residue preceding Pro (Suc-Ala-Arg-Pro-Phe-NH-Np: k(cat)/K(M)=97.1 /M/s), like that found for human Par14. In contrast to human Pin1, but similarly to Par14, Par45 does not accelerate the cis/trans interconversion of acidic substrates containing Glu-Pro bonds. It is preferentially located in the parasite nucleus. Single RNA interference (RNAi)-mediated knock-down showed that there was a growth inhibition in procyclic Trypanosoma brucei cells. These results identify Par45 as a phosphorylation-independent parvulin required for normal cell proliferation in a unicellular eukaryotic cell.

Microbial Peptidyl-Prolyl cis / trans Isomerases (PPIases): Virulence Factors and Potential Alternative Drug Targets

“…Although TgMIC5 seems to be involved in the maturation of other surface proteins by facilitating their proteolysis, the type of involvement of the parvulin-like domain in those processes is not clear (122,123). Besides that protein, TcPin1 and TcPar45 of T. cruzi, as well as their homologs TbPin1 and TbPar42 of Trypanosoma brucei, are the only parvulins described for protozoan parasites (124)(125)(126)(127). TcPin1 is able to complement the temperaturerelated phenotypes of its homolog Ess1 in S. cerevisiae, suggesting similar physiological functions (124).…”

Trypanosomatid Pin1‐Type Peptidyl‐Prolyl Isomerase Is Cytosolic and Not Essential for Cell Proliferation

“…For RNAi, T. brucei 29‐13 cells were transfected with the pZJM vector as previously described (Erben et al. ). To test the effects of RNAi, we added tetracycline (1 μg/ml) and cultivated the parasites for up to 9 days, diluting as required and assessed mRNA levels by Northern blotting.…”

“…), Tc Par14, and Tc Par45 (Erben et al. ). Only Tc Pin1 possesses the characteristics of Pin1‐type parvulins and shows a high degree of similarity with the previously characterized plant Pin1‐type parvulins.…”

“…Despite the well‐studied roles of parvulin‐type PPIases in higher eukaryotic, very little is known about the physiological functions of these enzymes in the TriTryp parasites (causative agents of Chagas' disease, African sleeping sickness, and leishmaniasis), where Pin1‐like PPIases display conserved features (Erben et al. , ; Goh et al. ).…”

Structure and function of the human parvulins Pin1 and Par14/17

“…Instead, N-terminal extended SDPs or two-and multi-domain proteins are found even in the simplest unicellular organisms, e.g. trypanosomes (Erben et al, 2010). Very often two or more parvulin representatives are expressed by eukaryotic cells -an evolutionary adaptation, certainly reflecting the complex compartmentation.…”