Genome complexity: rescuing stalled transcription (Introduction)

by David Turell @, Monday, December 05, 2016, 18:25 (933 days ago) @ David Turell

There is a way to correct stalled transcription problems by an existing mechanism. Absolutely correct transcription is vital for life to continue:

Ludwig Maximilian University of Munich researchers have elucidated a mechanism that recycles bacterial ribosomes stalled on messenger RNAs that lack termination codons.


One of these processes is the recycling of stalled ribosomes. Wilson and his research group have just completed a comprehensive structural study of ribosome recycling. The results of the study, which appears in the leading journal Nature, may identify promising points of attack for future antibiotics.

Ribosomes are the organelles that translate the nucleotide sequences encoded in messenger RNA molecules (mRNAs) into the amino-acid sequences of the corresponding proteins. The ribosome "reads" the nucleotide sequence in a fixed direction and is released from the mRNA only when it reaches a defined termination signal. Errors in synthesis or processing may, however, lead to the production of mRNAs that lack termination signals, causing the ribosome to stall while still attached to the mRNA and the growing protein. Cells have evolved several ways of detaching stalled ribosomes from the truncated mRNAs and recycling them for re-use.

Wilson's team has now employed cryo-electron microscopy to determine the structure of the bacterial recycling factor ArfA. Their analysis reveals how ArfA recognizes the stalled ribosome on a defective mRNA and recruits a so-called release factor, which detaches the incomplete protein. This then enables the stalled ribosome to be released from the mRNA in the normal manner by dissociation into its two component subunits. The subunits are then free to interact with another mRNA, thus allowing protein synthesis to proceed.

Comment: This mechanism could not have developed after the transcription mechanism developed by itself. It is obvious they had to be developed together all at once or continued replication of life would not have survived. Only God could do this.

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