Post-translational control of the Streptomyces lividans ClgR regulon by ClpP

Abstract

It has been shown previously that expression of the Streptomyces lividans clpP1P2 operon, encoding proteolytic subunits of the Clp complex, the clpC1 gene, encoding the ATPase subunit, and the lon gene, encoding another ATP-dependent protease, are all activated by ClgR. The ClgR regulon also includes the clgR gene itself. It is shown here that the degradation of ClgR and Lon is ClpP1/P2-dependent and that the two C-terminal alanines of these new substrates are involved in their stability. The ClpC1 protein, which does not end with two alanines, is also accumulated in a clpP1P2 mutant. The results presented here support the idea that ClpP1/P2 ensure post-translational control of ClgR regulon members, including ClgR itself.

ClgR regulation of chaperone and protease systems is essential for Mycobacterium tuberculosis parasitism of the macrophage

“…The B. subtilis CtsR and E. coli s 32 are both degraded by proteases under their transcriptional control (Arsène et al, 2000;Krüger et al, 2001). In Streptomyces, ClgR is itself degraded by ClpP and is recognized via two C-terminal alanines, in line with the ssrA tag of E. coli (Bellier et al, 2006). The Mycobacterium ClgR C-terminal residues Ala-Val-Ala-COOH are also consistent with the E. coli Clp recognition motif (Flynn et al, 2003), although experimental demonstration of Clp protease substrate selection in mycobacteria has yet to be performed.…”

“…Low-GC Gram-positive bacteria such as B. subtilis have evolved a negative control strategy using the transcriptional repressor CtsR. In contrast, the high-GC actinomycetes appear to have adopted a highly conserved transcriptional activator ClgR (clp gene regulator), which has been shown to control clp genes in Corynebacterium glutamicum (Engels et al, 2004(Engels et al, , 2005, Streptomyces lividans (Bellier & Mazodier, 2004;Bellier et al, 2006) and Bifidobacterium breve (Ventura et al, 2005). A homologue of ClgR exists in M. tuberculosis and its expression is highly upregulated in stress conditions such as heat shock (Stewart et al, 2002) and during macrophage infection (Schnappinger et al, 2003).…”

Crystal Structure of the Caseinolytic Protease Gene Regulator, a Transcriptional Activator in Actinomycetes

“…These results support the hypothesis that the regulation of clpC and clpP1P2 by ClgR is highly conserved within the actinomycetes. Similar to the clp gene regulators in Gram-negative and low GϩC Grampositive bacteria described above, convincing evidence was provided that the activity of ClgR is also controlled at the level of protein stability via ClpCP-mediated degradation (10,14). However, neither the environmental stimuli nor the molecular mechanism leading to stabilization of ClgR are known at present.…”

Acyl depsipeptide (ADEP) resistance in Streptomyces

“…ClpP1ClpP2 degrade s R 9, an unstable isoform of s R with an N-terminal extension of 55 amino acids (Kim et al, 2009). It is remarkable that ClpP1 degrades its two regulators, ClgR and s R 9 (Bellier et al, 2006;Kim et al, 2009), thereby establishing negative feedback loops by degrading two very different targets. Nevertheless, the stress-dependent transcription involving s R and a secondary promoter p2 makes only a minor contribution to the transcription rate of clpP1clpP2; it is mostly transcribed from the promoter p1 under the control of the activator ClgR.…”

“…ClpP1 degrades the PopR activator of the clpP3clpP4 operon. Therefore, clpP3clP4 is not expressed in the wild-type, but is expressed in the clpP1 mutant so that ClpP3 is produced (Bellier & Mazodier, 2004;Bellier et al, 2006;Viala et al, 2000;Viala & Mazodier, 2002, 2003. ClpP3 does not fully perform the role of ClpP1; this is clearly shown by the 'bald' phenotype of the clpP1 mutant, which fails to fully differentiate on various media (de Crécy-Lagard et al, 1999).…”