There are only a few protein repair enzymes known. One of them, Protein Iso-Aspartate Methyltransferases (PIMT), also known as Protein Carboxyl Methyltransferases (PCMT), is responsible for converting Iso-Aspartate (abnormal amino acid residues) to Aspartate (normal amino acid residues). PCMT is an enzyme found in a wide range of living organisms. In the present study, the amino acid sequence of PIMT of Shigella flexneri was retrieved and the 3D structure is predicted. Further, it is characterized by in silico approaches and its interaction with one of the target proteins i. e. rpoS is studied.