Peptidyl trans-hydrolase is an enzyme (E.C 220.127.116.11) which hydrolysis the ester bond in the middle of peptide and nucleotide of peptidyl-tRNA produced throughout the abortive translation, which happens about 10% of the time (Kurland and Ehvenberg, 1985; Bonin, et al., 2002). Peptidyl-tRNA also transpire because of expression of ORFs (Cruz-Vera, et al., 2003; Hernandez-Sanchez, et al., 1998; Tenson, et al., 1999) and macrolide action (Menninger and Coleman, 1993). Pth hydrolyses the ester bond betwixt the hydroxyl group at 2?- and 3?- position of the ribose at the 3′ end of the transfer RNA and the peptide which is attached to the peptidyl t-RNA and thus dissociated the peptide and the t-RNA from the ribosome during protein biosynthesis. Thus, the free t-RNA is reused for the ongoing process inside the cell (Cuzin, et al., 1967). Acummulation of peptidyl-t RNA and depletion of aminoacyl pool iside the cell leads to the toxic conditions (Menninger, 1979; Cruz-Vera, et al., 2000; Ibba & Soll, 1999; Menez, et al., 2000). later stop the protein synthesis inside the cell. Also ,the accumulation of the pth inside the the cell is toxic to avoid the toxicity because of the accumulation of the peptidyl t-RNA, hydrolysis of peptidyl t-RNA is essential (Atherly, 1978; Menninger, 1979; Menez, et a. 2000)
peptidyl- trans hydrolasese enzyme activity is universal. Human pth and the bacterial peptidyl-tRNA hydolase does not share any sequence or structural homology, but it was foundthat they perform the same biological function. This makes peptidyl-bility RNA hydrolase an attractive drug target for the antibiotics designing.
NEED FOR STUDY
Because of the presence of more than one virulence characterstics , the main foe connect A. baumannii lies back in caparesides in its capability to relate with that antimicrobial-resistance genes frequently leads to MDRS . so the consequences of Acinetobacter baumanii infectious has become major healthcare issue all over the world Because of the multidrugs resistant property of the pathogenic bacteria,( Bergogne-BerezinE et.al 1999 volume 9)
it is the need of the time to find out new drug targets, against which the lead molecules can be designed, which can be used as a future antibiotics. For designing of drugs against
a protein target molecule it is important to understand fundamental basic of protein function, which depends on the knowledge of enzyme. This interconnection basically relies on the 3-D structure of the enzyme which determine particular amino acids of the protein , charge, the chemistry of protein.
To design an antibiotic against pth , the structural details of Pth from various pathogenic bacterial strains are required. Earlier, crystal structures of Pth enzymes were known only from a few bacterial species. These included structures of Peptidyl trans hydrolase from Escherichia.coli (EcPth) (Schmitt, et al., 1997), Mycobacterium tuberculosis (MtPth) (Selvaraj, et al., 2007) Francisella tularensis (FtPth) (Clarke, et al., 2011), Mycobacterium smegmatis (MsPth) (Kumar et al 2012). The present thesis was intended to investigate the detailed three dimensional structure of AbPth from bacterial species, a gram-negative coccus bacteria Acinetobacter baumannii.
1. Isolation of genomic DNA from Acinetobacter baumannii (Abpth)
2. Cloning and expression
4. Crystallization of peptidyl-tRNA hydrolase (Abpth)