Saturation and specificity of the Lon protease of Escherichia coli.
Lon is an ATP-dependent protease of Escherichia coli. The lon mutation has a pleiotropic phenotype: UV sensitivity, mucoidy, deficiency for lysogenization by bacteriophage lambda and P1, and lower efficiency in the degradation of abnormal proteins. All of these phenotypes are correlated with the loss of protease activity. Here we examine the effects of overproduction of one Lon substrate, SulA, and show that it protects two other substrates from degradation. To better understand this protection, we mutagenized the sulA gene and selected for mutants that have partially or totally lost their ability to saturate the Lon protease and thus can no longer protect another substrate. Some of the SulA mutants lost their ability to protect RcsA from degradation but could still protect the O thermosensitive mutant protein (Ots). All of the mutants retained their capacity to induce cell division inhibition. It was also found that deletion of the C-terminal end of SulA affected its activity but did not affect its susceptibility to Lon. We propose that Lon may have more than one specificity for peptide cleavage.
Dervyn
E
E
Département de Biotechnologie, Institut Pasteur, Paris, France.
Canceill
D
D
Huisman
O
O
D049069:ATP-Dependent Proteases; D001426:Bacterial Proteins / Q000378:metabolism; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins; D049070:Protease La; D011485:Protein Binding; D012697:Serine Endopeptidases / Q000378:metabolism*; D013379:Substrate Specificity
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; C053139:sulA protein, E coli; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; C483567:Lon protein, E coli; D049070:Protease La