Biomaterial Database

The Escherichia coli chaperones involved in DNA replication. 1993

M Zylicz

University of Gdansk, Department of Molecular Biology, Poland.

Mutations in the Escherichia coli heat shock genes, dnaK, dnaJ or grpE, alter host DNA and RNA synthesis, degradation of other proteins, cell division and expression of other heat shock genes. They also block the initiation of DNA replication of bacteriophages lambda and P1, and the mini-F plasmid. An in vitro lambda DNA replication system, composed entirely of purified components, enabled us to describe the molecular mechanism of the dnaK, dnaJ and grpE gene products. DnaK, the bacterial hsp 70 homologue, releases lambda P protein from the preprimosomal complex in an ATP- and DnaJ-dependent reaction (GrpE-independent initiation of lambda DNA replication). In this paper, I show that, when GrpE is present, lambda P protein is not released from the preprimosomal complex, rather it is translocated within the complex in such a way that it does not inhibit DnaB helicase activity. Translocation of lambda P triggers the initiation event allowing DnaB helicase to unwind DNA near the ori lambda sequence, leading to efficient lambda DNA replication. Chaperone activity of the DnaK-DnaJ-GrpE system is first manifested in the selective binding of these heat shock proteins to the preprimosomal complex, followed by its ATP-dependent rearrangement. I show that DnaJ not only tags the preprimosomal complex for recognition by DnaK, but also stabilizes the multi-protein structure. GrpE also participates in the binding of DnaK to the preprimosomal complex by increasing DnaK's affinity to those lambda P proteins which are already with DnaJ.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D011506	Proteins	Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.	Gene Products, Protein,Gene Proteins,Protein,Protein Gene Products,Proteins, Gene
D004261	DNA Replication	The process by which a DNA molecule is duplicated.	Autonomous Replication,Replication, Autonomous,Autonomous Replications,DNA Replications,Replication, DNA,Replications, Autonomous,Replications, DNA
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005798	Genes, Bacterial	The functional hereditary units of BACTERIA.	Bacterial Gene,Bacterial Genes,Gene, Bacterial
D006360	Heat-Shock Proteins	Proteins which are synthesized in eukaryotic organisms and bacteria in response to hyperthermia and other environmental stresses. They increase thermal tolerance and perform functions essential to cell survival under these conditions.	Stress Protein,Stress Proteins,Heat-Shock Protein,Heat Shock Protein,Heat Shock Proteins,Protein, Stress
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D050956	HSP40 Heat-Shock Proteins	A family of heat-shock proteins that contain a 70 amino-acid consensus sequence known as the J domain. The J domain of HSP40 heat shock proteins interacts with HSP70 HEAT-SHOCK PROTEINS. HSP40 heat-shock proteins play a role in regulating the ADENOSINE TRIPHOSPHATASES activity of HSP70 heat-shock proteins.	DnaJ Protein,HSP40 Heat-Shock Protein,HSP40 Protein,Heat-Shock Proteins 40,DnaJ Proteins,HSP40 Protein Family,HSP40 Proteins,Heat Shock Protein 40 Family,Heat-Shock Protein 40,HSP40 Heat Shock Protein,HSP40 Heat Shock Proteins,Heat Shock Protein 40,Heat Shock Proteins 40,Heat-Shock Protein, HSP40,Heat-Shock Proteins, HSP40,Protein, DnaJ,Protein, HSP40,Protein, HSP40 Heat-Shock,Proteins, HSP40 Heat-Shock
D018833	Chaperonins	A family of multisubunit protein complexes that form into large cylindrical structures which bind to and encapsulate non-native proteins. Chaperonins utilize the energy of ATP hydrolysis to enhance the efficiency of PROTEIN FOLDING reactions and thereby help proteins reach their functional conformation. The family of chaperonins is split into GROUP I CHAPERONINS, and GROUP II CHAPERONINS, with each group having its own repertoire of protein subunits and subcellular preferences.	Chaperonin,Chaperonin Complex,Chaperonin Complexes,Chaperonin Family,Chaperonin Protein Complex,Complex, Chaperonin
D018840	HSP70 Heat-Shock Proteins	A class of MOLECULAR CHAPERONES found in both prokaryotes and in several compartments of eukaryotic cells. These proteins can interact with polypeptides during a variety of assembly processes in such a way as to prevent the formation of nonfunctional structures.	Heat-Shock Proteins 70,Heat Shock 70 kDa Protein,Heat-Shock Protein 70,HSP70 Heat Shock Proteins,Heat Shock Protein 70,Heat Shock Proteins 70,Heat-Shock Proteins, HSP70
D029968	Escherichia coli Proteins	Proteins obtained from ESCHERICHIA COLI.	E coli Proteins