SpoT
Encyclopedia
SpoT is a bacterial protein that hydrolizes
alarmone
s, (p)ppGpp, in the bacterial stringent response. Its hydrolase activity is Mn2+-dependent with a conserved His-Asp (HD) motif. In E coli, SpoT protein consistent of 693 amino acids. SpoT is belongs to the RSH protein family.
It is bifunctional, has both hydrolase and synthase activities. When relA is deleted, E coli still can produce (p)ppGpp by SpoT.
SpoT can sense many sources of nutrient stress other than amino acid starvation and to respond by limiting hydrolase. The acyl carrier protein (ACP) binds to the TGS domain of SpoT and this binding is probably influenced by the ratio of unacylated ACP to acylated ACP in the cell. Fatty acid starvation lead to a shift in the balance of the two SpoT actvities in favor of synthesis. Phosphate starvation is sensed by SpoT hydrolase to elevate (p)ppGpp, which induces IraP, a RssB antiadaptor that antagonizes RssB activation of RpoS turnover, thereby inducing RpoS.
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
alarmone
Alarmone
Alarmone is an intracellular signal molecule that is produced due to harsh environmental factors. They regulate the gene expression at transcription level. Alarmones are produced in high concentrations when harsh environmental factors occur in bacteria and plants, such as lack of amino acids to...
s, (p)ppGpp, in the bacterial stringent response. Its hydrolase activity is Mn2+-dependent with a conserved His-Asp (HD) motif. In E coli, SpoT protein consistent of 693 amino acids. SpoT is belongs to the RSH protein family.
It is bifunctional, has both hydrolase and synthase activities. When relA is deleted, E coli still can produce (p)ppGpp by SpoT.
SpoT can sense many sources of nutrient stress other than amino acid starvation and to respond by limiting hydrolase. The acyl carrier protein (ACP) binds to the TGS domain of SpoT and this binding is probably influenced by the ratio of unacylated ACP to acylated ACP in the cell. Fatty acid starvation lead to a shift in the balance of the two SpoT actvities in favor of synthesis. Phosphate starvation is sensed by SpoT hydrolase to elevate (p)ppGpp, which induces IraP, a RssB antiadaptor that antagonizes RssB activation of RpoS turnover, thereby inducing RpoS.