GENE223 Module 1 - Bacterial Model Systems

Describe the two regulatory proteins that affect the starvation-driven fruiting bodies of M. xanthus

Starvation increases MrpC levels, which causes an increase in C-signal, and activates expression of FruA. C-signal acts as an enhancer for MrpC and FruA activity. Both of these proteins enhance the dev operon which produces DevI. DevI delays spore formation within nascent fruiting bodies, but if overproduced DevI inhibits itself.

What is Multicellular fruiting body development in Myxobacteria?

This is a cell cycle initiated by Myxobacteria cells at high density on a solid surface when starved.

Describe the protein signals that occur that cause S. coelicolor to produce hyphae and then spores.

BldG protein activates bldN which is a sigma factor. bldN directs transcription of bldM which produces a response-regulator that pushes the cell towards aerial growth, producing spores.

An addition factor is BldD which binds to and represses bldN in a substrate mycelium

How does the starvation signal cause downstream responses that slow growth and cause spores to form?

Starvation signals causes BldD to be inhibited, this allows bldN to facilitate the expression of downstream factors that slow growth and produce hyphae.

Why do bacteria produce spores?

Spores are highly resistant to temperature, radiation, chemical and enyyme abiotic factors, and can survive for extremely long times as a dormant state for the bacteria.