Study BMB 400 Chapter 14 Termination Flash Cards

 
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BMB 400 Chapter 14 Termination

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S8 protein
-ribosomal protein S8 binds 16S rRNA and own mRNA
-translation repressed only when need for S8 protein satisfied
Ribosomal Proteins repress own synthesis?!
-have to regulate own growth rate
-operon expression regulated by ribosome []
-ribosomal proteins bind to the mRNA near the start site operon genes
-prevents ribosomes from binding
What if Protein or RNA binds near the ribosome-binding site?
-negatively regulates bacterial translation initiation
-want to impair association of mRNA with 16S rRNA of 30S subunit
-or, mRNA binds with self to mask RBS units
translation regulation
-gene expression mostly regulated at transcription level b/c very effective
-responds rapdly to external signals (skip the time required to mRNA transcription, RNA processing and/or mRNA transport to the cytoplasm)
-typically stops at initiation
Puromycin
-antibiotic that kills bacteria
-binds in the A site
-participates in peptide bond formation
-diffuse out of ribosome
-peptides dissociate from ribosome as incomplete
How do antibiotics work?
~40 % of the known antibiotics are inhibitors of the translational machinery
Ribosome recycling factor (RRF)
-uses EF-G and IF3 to recycle ribosome
Class I release factors resemble...
...tRNA
-anticodon
-GGQ motif that reaches into the peptidyl transferase center
-cleavage mechanism not understood
Class II RFs
(prokaryote: RF3; eukaryote: eRF3)
-GTP-reguated
-stimulate the dissociation of the class I RF form the ribosome after release of the polypeptide chain
-binds only after polypeptide release
-drives the dissociation of the class I release factor
Class I release factors (RFs)
-recognize stop codons and trigger hydrolysis of the peptide chain
-stimulates polypeptide release through a GGQ motif
RF1 and RF2
-recognize different release factors
-both recognize UAA (most common)
eRF1
-euk release factor recognizes all 3 stop codons
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