Streptomycin synthesis

Antibiotics. The genes involved in the synthesis of a variety of antibiotics have been isolated (34,35). These include antibiotics such as erythromycin, streptomycin, and also peptide antibiotics such as gramicidin and tyrocidin. Characterization of these gene products facUitates the design of novel antibiotics. In addition, overexpression of some of these gene products is also expected to improve the yield of the antibiotic (34,35). 

Streptomycin Streptomyces griseus Gram-negative bacteria Protein synthesis... 

Most aiititubercular drag s are bacteriostatic (slow or retard the growth of bacteria) against the M. tuberculosis bacillus. These dm usually act to inhibit bacterial cell wall synthesis, which slows the multiplication rate of the bacteria. Only isoniazid is bactericidal, with rifampin and streptomycin having some bactericidal activity. 

Chloroplast protein synthesis is controlled largely at the post-transcriptional level [20,21] and can be repressed by the inclusion of antibiotics such as streptomycin in the sprouting medium. Streptomycin binds to the 16S rRNA and causes the ribosome to misread the mRNA sequence, producing incorrect and non-functional proteins [22]. 

Transcriptional inhibitors could be used simultaneously. Rifampicin blocks chloroplast and mitocondrian RNA synthesis [23, 24], while tagetitoxin is a very specific inhibitor of chloroplast RNA polymerase [25]. Treatment with these antibiotics does not inhibit Rubisco SSU synthesis since the promoter is part of the nuclear genome, while the cytosolic ribosomes are not affected by streptomycin. Therefore SSU promoters can be used to drive transgene expression and facilitate the accumulation of recombinant proteins. Expressed proteins are targeted to a suitable cellular compartment, such as the cytoplasm, apoplastic space or chloroplast, depending on the nature of the protein. 

Fig. 3.7 Transgenic rapeseeds were sprouted in an airlift tank with (lane 1) and without (lane 2) of streptomycin at 100 mg L-1. Total proteins were extracted, separated by SDS-PAGE and stained with Coomassie blue. The synthesis of Rubisco large and small subunits was inhibited as clearly shown in lane 2.

Synthesis and Characterisation of Molecularly Imprinted Polymer Nanoparticles for Streptomycin for Use as Solid Phase Extraction Materials... 

Other key classes of antibacterials include the tetracyclines (Aureomycin, Terramycin), macrolides (erythromycin, Zithromax, Biaxin), and aminoglycosides (streptomycin, amikacin, neomycin). These antibacterials are protein synthesis inhibitors. 

Pharmacology Aminosalicylic acid is bacteriostatic against Mycobacterium tuberculosis. It inhibits the onset of bacterial resistance to streptomycin and isoniazid. The mechanism of action has been postulated to be inhibition of folic acid synthesis (but without potentiation with antifolic compounds) or inhibition of synthesis of the cell wall component, mycobactin, thus reducing iron uptake by M. tuberculosis. 

Pharmacology Streptomycin sulfate is a bactericidal antibiotic that interferes with normal protein synthesis. 

Tetracyclines are a family of antibiotics which display a characteristic 4-fused-core ring structure (Figure 1.16). They exhibit broad antimicrobial activity and induce their effect by inhibiting protein synthesis in sensitive microorganisms. Chlortetracycline was the first member of this family to be discovered (in 1948). Penicillin G and streptomycin were the only antibiotics in use at that time, and chlortetracycline was the first antibiotic employed therapeutically that retained its antimicrobial properties upon oral administration. Since then, a number of additional tetracyclines have been discovered (all produced by various strains of Streptomyces), and a variety of semi-synthetic derivatives have also been prepared (Table 1.18). 

DNA synthesis inhibitors Fluoroquinolones Antimycobacterials Isoniazid Rifampin Ethambutol Pyrizinamide Streptomycin... 

Streptomycin and other aminoglycosides inhibit bacterial protein synthesis by binding... 

The selection of transformed chloroplasts usually involves the use of an antibiotic resistance marker. Spectinomycin is used most routinely because of the high specificity it displays as a prokaryotic translational inhibitor as well as the relatively low side effects it exerts on plants. The bacterial aminoglycoside 3 -adenyltransferase gene (ciadA) confers resistance to both streptomycin and spectinomycin. The aadA protein catalyzes the covalent transfer of an adenosine monophosphate (AMP) residue from adenosine triphosphate (ATP) to spectinomycin, thereby converting the antibiotic into an inactive form that no longer inhibits protein synthesis for prokaryotic 70S ribosomes that are present in the chloroplast. 

All aminoglycosides act by inhibiting protein synthesis of bacteria by directly combining with ribosomes. They penetrate the outer cytoplasmic membrane and inhibit protein synthesis. Streptomycin combines with the bacterial 30S ribosomes and inteferes with the mRNA-ribosome combination. Other aminoglycosides bind to additional sites on SOS subunit as well as to 30S-50S interface. 

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