Cloned (Comment) | Organism |
---|---|
gene lon, functional recombinant expression of wild-type and mutant enzymes in Escherichia coli strain W3110 | Escherichia coli |
Protein Variants | Comment | Organism |
---|---|---|
Q220C | site-directed mutagenesis, the mutant reproducibly yields fast and robust intermolecular disulfide crosslinking. The cysteine-based disulfide crosslinking is responsible for the formation of the SDS-resistant dimers | Escherichia coli |
V217A/Q220A | site-directed mutagenesis, residues Val217 and Gln220 are present in a region predicted to form intermolecular coiled coils between hexamers, the Lon mutant variant (LonVQ) forms a dodecamer with increased stability compared to wild-type. The dodecamer is active, but it exhibits alterations in substrate selection and/or degradation. Mutant LonVQ is altered in recognition of dodecamer-sensitive substrates in vivo | Escherichia coli |
V217C | site-directed mutagenesis, the mutant reproducibly yields fast and robust intermolecular disulfide crosslinking. The cysteine-based disulfide crosslinking is responsible for the formation of the SDS-resistant dimers | Escherichia coli |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Mg2+ | required | Escherichia coli |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
IbpA + H2O | Escherichia coli | - |
? | - |
? | |
SulA + H2O | Escherichia coli | a cell division inhibitor | ? | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Escherichia coli | P0A9M0 | - |
- |
Purification (Comment) | Organism |
---|---|
recombinant wild-type and mutant enzymes from Escherichia coli strain W3110 | Escherichia coli |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
IbpA + H2O | - |
Escherichia coli | ? | - |
? | |
SulA + H2O | - |
Escherichia coli | ? | - |
? | |
SulA + H2O | a cell division inhibitor | Escherichia coli | ? | - |
? |
Subunits | Comment | Organism |
---|---|---|
dodecamer | the larger assembly has decreased ATPase activity and displays substrate-specific alterations in degradation compared to the hexamer. The enzyme dodecamer successfully completes many of the Lon protease's important regulatory functions while modifying substrate choice, perhaps to better manage protein quality control under conditions such as UV, heat, and oxidative stress. Identification of N domain interactions underlying Lon dodecamer formation. The Lon N domains are primarily responsible for dodecamer formation, the Lon dodecamer forms via putative N domain coiled-coil interactions. Analytical ultracentrifugation | Escherichia coli |
homohexamer | Lon assembles into a barrel-shaped homohexamer with the proteolytic active sites sequestered in an internal chamber, largely inaccessible to folded proteins. This architecture serves to prevent degradation of non-substrate proteins. Analysis of hexamer-hexamer interactions, usage of an ellipsoidal electron density map sufficient to model two barrel-shaped hexamers at the distal ends of the dodecamer corresponding to the Lon ATPase and protease modules. The two barrels are bridged by six extended helical structures, which are modeled as six N domain dimers forming end-to-end interactions that mimic two-stranded, antiparallel coiled coils | Escherichia coli |
More | each Lon monomer contains three functional subregions: the N domain, AAA+ ATPase module, and a protease domain. The ATPase and protease domains are the most well-conserved regions of Lon | Escherichia coli |
Synonyms | Comment | Organism |
---|---|---|
lon | - |
Escherichia coli |
Lon AAA+ protease | - |
Escherichia coli |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
37 | - |
assay at | Escherichia coli |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
8 | - |
assay at | Escherichia coli |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
ATP | - |
Escherichia coli |
General Information | Comment | Organism |
---|---|---|
evolution | Lon is a highly conserved member of the AAA+ (ATPases associated with diverse cellular activities) protease family | Escherichia coli |
malfunction | the Lon mutant variant V217A/Q220A (LonVQ) forms a dodecamer with increased stability compared to wild-type. Cells expressing only LonVQ are healthier than Lon-deficient strains during normal growth and perform similarly to wild-type Lon in a panel of in vivo bioassays except for degradation of small heat shock proteins. At 37°C, the enzyme-ddeficient DELTAlon strain grows significantly slower than the wild-type strain and never establishes a true exponential phase, but loss of Lon activity is not deleterious to viability | Escherichia coli |
physiological function | the protein quality control network (pQC) plays critical roles in maintaining protein and cellular homeostasis, especially during stress. Protease Lon is one of the central proteases responsible for protein quality control (pQC). It is the principal enzyme that degrades most unfolded or damaged proteins. Degradation by Lon also controls cellular levels of several key regulatory proteins. Analysis of biological roles of the Lon dodecamer. The enzyme dodecamer successfully completes many of the Lon protease's important regulatory functions while modifying substrate choice, perhaps to better manage protein quality control under conditions such as UV, heat, and oxidative stress | Escherichia coli |