Regulation of RcsA by the ClpYQ (HslUV) protease in Escherichia coli
Kuo, Mei-Shiue and Chen, Kuei-Peng and Wu, Whi Fin,, 150, 437-446 (2004),
doi = https://doi.org/10.1099/mic.0.26446-0,
publicationName = Microbiology Society,
issn = 1350-0872,
abstract= Escherichia coli ClpYQ protease and Lon protease possess a redundant function for degradation of SulA, a cell division inhibitor. An experimental cue implied that the capsule synthesis activator RcsA, a known substrate of Lon, is probably a specific substrate for the ClpYQ protease. This paper shows that overexpression of ClpQ and ClpY suppresses the mucoid phenotype of a lon mutant. Since the cpsB (wcaB) gene, involved in capsule synthesis, is activated by RcsA, the reporter construct cpsB–lacZ was used to assay for β-galactosidase activity and thus follow RcsA stability. The expression of cpsB–lacZ was increased in double mutants of lon in combination with clpQ or/and clpY mutation(s) compared with the wild-type or lon single mutants. Overproduction of ClpYQ or ClpQ decreased cpsB–lacZ expression. Additionally, a PBAD–rcsA fusion construct showed quantitatively that an inducible RcsA activates cpsB–lacZ expression. The effect of RcsA on cpsB–lacZ expression was shown to be influenced by the ClpYQ activities. Moreover, a rcsA Red –lacZ translational fusion construct showed higher activity of RcsARed–LacZ in a clpQ clpY strain than in the wild-type. By contrast, overproduction of cellular ClpYQ resulted in decreased β-galactosidase levels of RcsARed–LacZ. Taken together, the data indicate that ClpYQ acts as a secondary protease in degrading the Lon substrate RcsA.,
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