A mutation in the N domain of E . coli Lon stabilizes dodecamers and は selectively alters degradation of model substrates

にぬ E. coli Lon, an ATP-dependent AAA+ protease, recognizes and degrades many different にね substrates, including the RcsA and SulA regulatory proteins. More than a decade ago, the E240K にの mutation in the N domain of Lon was shown to prevent degradation of RcsA but not SulA in vivo. には Here, we characterize the biochemical properties of the E240K mutant in vitro and present にば evidence that the effects of this mutation are complex. For example, Lon exists almost にぱ exclusively as a dodecamer, whereas wild-type Lon equilibrates between hexamers and にひ dodecamers. Moreover, Lon displays degradation defects in vitro that do not correlate in any ぬど simple fashion with degron identity, substrate stability, or dodecamer formation. The Lon ぬな sequence segment near residue 240 is known to undergo nucleotide-dependent conformational ぬに changes, and our results suggest that this region may be important for coupling substrate binding ぬぬ with allosteric activation of Lon protease and ATPase activity. ぬね ぬの ぬは on S etem er 3, 2017 by gest http/jb.asm .rg/ D ow nladed fom