dITP/XTP pyrophosphatase; Pyrophosphatase that catalyzes the hydrolysis of nucleoside triphosphates to their monophosphate derivatives, with a high preference for the non-canonical purine nucleotides XTP (xanthosine triphosphate), dITP (deoxyinosine triphosphate) and ITP. Seems to function as a house-cleaning enzyme that removes non-canonical purine nucleotides from the nucleotide pool, thus preventing their incorporation into DNA/RNA and avoiding chromosomal lesions. Belongs to the HAM1 NTPase family.

Ribonuclease PH; Phosphorolytic 3'-5' exoribonuclease that plays an important role in tRNA 3'-end maturation. Removes nucleotide residues following the 3'-CCA terminus of tRNAs; can also add nucleotides to the ends of RNA molecules by using nucleoside diphosphates as substrates, but this may not be physiologically important. Probably plays a role in initiation of 16S rRNA degradation (leading to ribosome degradation) during starvation.

Heat-inducible transcription repressor HrcA; Negative regulator of class I heat shock genes (grpE-dnaK- dnaJ and groELS operons). Prevents heat-shock induction of these operons.

Protein GrpE; Participates actively in the response to hyperosmotic and heat shock by preventing the aggregation of stress-denatured proteins, in association with DnaK and GrpE. It is the nucleotide exchange factor for DnaK and may function as a thermosensor. Unfolded proteins bind initially to DnaJ; upon interaction with the DnaJ-bound protein, DnaK hydrolyzes its bound ATP, resulting in the formation of a stable complex. GrpE releases ADP from DnaK; ATP binding to DnaK triggers the release of the substrate protein, thus completing the reaction cycle. Several rounds of ATP-dependent i [...]