Binding and cleavage of E. coli HUbeta by the E. coli Lon protease.

ABSTRACT: The Escherichia coli Lon protease degrades the E. coli DNA-binding protein HUbeta, but not the related protein HUalpha. Here we show that the Lon protease binds to both HUbeta and HUalpha, but selectively degrades only HUbeta in the presence of ATP. Mass spectrometry of HUbeta peptide fragments revealed that region K18-G22 is the preferred cleavage site, followed in preference by L36-K37. The preferred cleavage site was further refined to A20-A21 by constructing and testing mutant proteins; Lon degraded HUbeta-A20Q and HUbeta-A20D more slowly than HUbeta. We used optical tweezers to measure the rupture force between HU proteins and Lon; HUalpha, HUbeta, and HUbeta-A20D can bind to Lon, and in the presence of ATP, the rupture force between each of these proteins and Lon became weaker. Our r

SUBMITTER: Liao JH 

PROVIDER: S-EPMC2800966 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature