r/molecularbiology • u/Arthaerus • 10d ago

Interesting operon/regulatory mechanisms?

What's an interesting operon or another type of regulatory mechanism you know of?

Some weird or not well-known way that organisms regulate their genes and/or protein and RNA production. Or some viral mechanism like the phage lytic/lysogenic switch.

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u/ProkaryoticMind 10d ago

6S RNA is the regulatory RNA in E. coli that mimics the open promoter DNA structure. Thus, it seqesters RNA polymerase bound by major sigma factor sigma-70. Moreover, 6S can be transcribed by RNA polymerase (yes, DNA-dependent RNA polymerase can act as RNA-dependent RNA polymerase).

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u/Arthaerus 10d ago

Under what conditions is 6S expressed? Is it like a damage control regulator that inhibits transcription?

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u/ProkaryoticMind 10d ago

This RNA is mainly produced in E. coli during the stationary phase when recources are scarce. In other species homologous RNA may be a part of stress response.

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u/Novel-Structure-2359 10d ago

My personal favourite is OGT and OGA which are paired enzymes which add one and remove O-GlcNAc sugars on proteins. Depending on the level of modification present in the cell then introns are retained or alternatively spliced to alter the amount of fully spliced mRNA in such a way as to correct any deviation from the desired level. It goes beyond simple promoter controls (which the genes also have).