title: Proline racemases: insights into Trypanosoma cruzi peptides containing D-proline.
abstract: Trypanosoma cruzi proline racemases (TcPRAC) are homodimeric enzymes that interconvert the L and D-enantiomers of proline. At least two paralogous copies of proline racemase (PR) genes are present per parasite haploid genome and they are differentially expressed during T. cruzi development. Non-infective epimastigote forms that overexpress PR genes differentiate more readily into metacyclic infective forms that are more invasive to host cells, indicating that PR participates in mechanisms of virulence acquisition. Using a combination of biochemical and enzymatic methods, we show here that, in addition to free D-amino acids, non-infective epimastigote and infective metacyclic parasite extracts possess peptides composed notably of D-proline. The relative contribution of TcPRAC to D-proline availability and its further assembly into peptides was estimated through the use of wild-type parasites and parasites over-expressing TcPRAC genes. Our data suggest that D-proline-bearing peptides, similarly to the mucopeptide layer of bacterial cell walls, may be of benefit to T. cruzi by providing resistance against host proteolytic mechanisms.
authors.affiliation: Département d'Immunologie, Laboratoire d'Immunobiologie des Infections à Trypanosoma, Institut Pasteur, Paris, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Coatnoan
authors.forename: Armand
authors.initials: A
authors.lastname: Berneman
authors.forename: Nathalie
authors.initials: N
authors.lastname: Chamond
authors.forename: Paola
authors.initials: P
authors.lastname: Minoprio
mesh_terms: D000591:Amino Acid Isomerases / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014349:Trypanosoma cruzi / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D015800:Protozoan Proteins; D000591:Amino Acid Isomerases; C022451:proline racemase