Repression-Trp aporepressor dimer binds high tryptophan, changes conformation with high affinity for trp operator

Tryptophan is a corepressor

TLS Online TPP Program

#Id: 3858

#Unit 5. Developmental Biology

Cell Aggregation & Differentiation is common to all Dictyostelids.
It consists of an interconnected programme of cell movement and cell differentiation.

TLS Online TPP Program

#Id: 3859

#Unit 5. Developmental Biology

The binding of ammonia to the sensor domain of DhkC leads to the activation of its histidine kinase activity and to the autophosphorylation of a DhkC histidine residue.

TLS Online TPP Program

#Id: 3860

#Unit 5. Developmental Biology

The phosphoryl group is transferred,

From histidine residue of DhkC  aspartate of DhkC histidine in phospho-transfer intermediate RdeA aspartate of RR of RegA

TLS Online TPP Program

#Id: 3861

#Unit 5. Developmental Biology

When the ratio of PSF relative to that of bacteria exceeds a certain threshold, cells stop proliferating and initiate the expression of genes that are required for their aggregation.

TLS Online TPP Program

#Id: 3862

#Unit 5. Developmental Biology

Early on during aggregation, gene expression requires the activity of cAMP-dependent protein kinase.

TLS Online TPP Program

#Id: 3863

#Unit 5. Developmental Biology

Ammonia inhibits PKA by indirectly activating cAMP hydrolysis via DhkC-RdeA mediated phosphorylation of RegA.