or protein synthesis, involves the decoding of an mRNA message ..

Bacterial Initiation of Protein Synthesis Begins Near a Shine-Dalgarno Sequence in mRNA

Structure and Function of Bacterial Cells

N2 - Many antibiotics inhibit the growth of sensitive bacteria by interfering with ribosome function. However, discovery of new protein synthesis inhibitors is curbed by the lack of facile techniques capable of readily identifying antibiotic target sites and modes of action. Furthermore, the frequent rediscovery of known antibiotic scaffolds, especially in natural product extracts, is timeconsuming and expensive and diverts resources that could be used toward the isolation of novel lead molecules. In order to avoid these pitfalls and improve the process of dereplication of chemically complex extracts, we designed a two-pronged approach for the characterization of inhibitors of protein synthesis (ChIPS) that is suitable for the rapid identification of the site and mode of action on the bacterial ribosome. First, we engineered antibiotic-hypersensitive Escherichia coli strains that contain only one rRNA operon. These strains are used for the rapid isolation of resistance mutants in which rRNA mutations identify the site of the antibiotic action. Second, we show that patterns of drug-induced ribosome stalling on mRNA, monitored by primer extension, can be used to elucidate the mode of antibiotic action. These analyses can be performed within a few days and provide a rapid and efficient approach for identifying the site and mode of action of translation inhibitors targeting the bacterial ribosome. Both techniques were validated using a bacterial strain whose culture extract, composed of unknown metabolites, exhibited protein synthesis inhibitory activity; we were able to rapidly detect the presence of the antibiotic chloramphenicol.

| The function of the ribosomal protein S1 in the elongation cycle of bacterial protein synthesis …

Protein Synthesis -Translation and Regulation

AB - Many antibiotics inhibit the growth of sensitive bacteria by interfering with ribosome function. However, discovery of new protein synthesis inhibitors is curbed by the lack of facile techniques capable of readily identifying antibiotic target sites and modes of action. Furthermore, the frequent rediscovery of known antibiotic scaffolds, especially in natural product extracts, is timeconsuming and expensive and diverts resources that could be used toward the isolation of novel lead molecules. In order to avoid these pitfalls and improve the process of dereplication of chemically complex extracts, we designed a two-pronged approach for the characterization of inhibitors of protein synthesis (ChIPS) that is suitable for the rapid identification of the site and mode of action on the bacterial ribosome. First, we engineered antibiotic-hypersensitive Escherichia coli strains that contain only one rRNA operon. These strains are used for the rapid isolation of resistance mutants in which rRNA mutations identify the site of the antibiotic action. Second, we show that patterns of drug-induced ribosome stalling on mRNA, monitored by primer extension, can be used to elucidate the mode of antibiotic action. These analyses can be performed within a few days and provide a rapid and efficient approach for identifying the site and mode of action of translation inhibitors targeting the bacterial ribosome. Both techniques were validated using a bacterial strain whose culture extract, composed of unknown metabolites, exhibited protein synthesis inhibitory activity; we were able to rapidly detect the presence of the antibiotic chloramphenicol.

Proteins are assembled from amino acids using information encoded in genes

Thus, the genetic code is determined by specific nuleotide basesequences in chromosomal DNA; the amino acid sequence in a proteindetermines the properties and function of the protein; and sequence ofsugars in bacterial lipopolysaccharides determines unique cell wallproperties for pathogens. The primary structure of amacromolecule will drive its function, and differences withinthe primary structure of biological macromoleculesaccounts for the immense diversity of life


BRCA1 Gene - GeneCards | BRCA1 Protein | BRCA1 Antibody

Ribosomes have several active centers (Fig 6.27)
- binding sites of the ribosome are large
- there are different locations for several ribosomal activities
- 30s:
- binds mRNA
- binds initiator tRNA
- 50s:
- peptidyl transferase center
- responsible for translocation
- 70s:
- distinct P and A sites
- the tRNAs are very bulky and the problem of fitting them intoa ribosome is solved by a turn in the mRNA
- this turn causes the tRNAs to become angled which forces translocation(the moving of the tRNAs during elongation) to occur
- The 30s ribosome has several active centers, one of which isthe S1 protein (Fig 6.26)
- Initial bonding of the mRNA to the 30s subunit requiresthe S1 protein which has an affinity for single stranded nucleicacids
- The S1 protein is responsible for maintaining the single strandedstate of mRNA that is bound to it
The role of rRNA in protein synthesis
- there is evidence that rRNA interacts with mRNA and tRNA ateach stage of translation and is not just static
- the proteins are thought to be necessary to maintain the rRNAin a structure in which it can perform its catalytic functions
- recent studies suggest that the rRNA of the large subunit hasthe catalytic activity of the peptidyl transferase which fitswith the notion that the ribosome evolved from functions originallypossessed by RNA

CD55 Gene - GeneCards | DAF Protein | DAF Antibody

-site at which protein synthesis occurs
-site where interaction between mRNA and tRNA occurs
-the general structure of the ribosome is conserved between prokaryotesand eukaryotes,
but there are differences in size and composition