Live, Attenuated Vaccines Microorganisms can be attenuated or disabled so that they lose their ability to cause significant disease but retain their capacity for transient growth within an inoculated host.

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#Unit 3. Fundamental Processes

RNase E and PNPase, along with a helicase and another accessory enzyme, form a multiprotein complex called the degradosome.

#Id: 6761

#Unit 3. Fundamental Processes

Cytoplasmic mRNAs are degraded by one of the three pathways. For most mRNAs, the deadenylation-dependent pathway is followed These dense regions of cytoplasm contain the decapping enzyme (DCP1/DCP2), activators of decapping (DHH, PAT1, LSM1-7), and the major 5′→3′ exoribonuclease XRN1, as well as densely associated mRNAs

#Id: 6762

#Unit 3. Fundamental Processes

The exposed cap is then removed by a decapping enzyme (DCP1/DCP2), unprotected mRNA susceptible to degradation by XRN1, a 5′→3′ exoribonuclease. Removal of the poly(A) tail also makes mRNAs susceptible to degradation by cytoplasmic exosomes containing 3′→5′ exonucleases.

#Id: 6763

#Unit 3. Fundamental Processes

#Id: 6764

#Unit 3. Fundamental Processes

#Id: 6765

#Unit 3. Fundamental Processes

P bodies are dense cytoplasmic domains many times the size of a ribosome. They are sites of translational repression that contain no ribosomes or translation factors. They are also major sites of mRNA degradation in the cytoplasm. Exon-junction complexes upf complex functions in nonsense-mediated decay and induces degradation of the mRNA by P body–associated 5′→3′ exoribonuclease XRN1