Proteome analysis of Streptomyces coelicolor mutants affected in the proteasome system reveals changes in stress-responsive proteins

Abstract

Prokaryotic 20S proteasomes are confined to archaebacteria and actinomycetes. Bacterial targets of this compartmentalized multi-subunit protease have not yet been identified and its physiological function in prokaryotes remains unknown. In this study, intracellular and extracellular proteomes of Streptomyces coelicolor A3(2) mutants affected in the structural genes of the 20S proteasome, in the gene encoding the presumed proteasome-accessory AAA ATPase ARC, or in two putative proteasome-associated actinomycete-specific genes (sco1646, sco1647) were analysed, revealing modified patterns of stress-responsive proteins. In addition, the extracellular protease profile of the sco1647 mutant was significantly altered. The most prominent change, common to the four mutants, was a strongly increased level of the non-heme chloroperoxidase SCO0465, coinciding with an increased resistance to cumene hydroperoxide.

In vivo gene silencing identifies the Mycobacterium tuberculosis proteasome as essential for the bacteria to persist in mice

“…These results are consistent with the phenotypes of mutants of the proteasome associated genes mpa and pafA 19 . Increased resistance to organic peroxide has also been reported for S. coelicolor proteasome mutants and was accompanied by increased levels of haloperoxidase 29 . The mechanisms by which the core proteasome protects Mtb against nitrosative damage may include removal of nitrosylated proteins, as demonstrated in mammalian cells 30 .…”

Genetic and Proteomic Analyses of Pupylation in Streptomyces coelicolor

“…This substitution obviates the need for the Dop-catalyzed deamidation of Pup (which precedes pupylation in most other bacteria) and thus leaves open questions about the function of the Dop in S. coelicolor. As was the case in M. tuberculosis, it has been reported that the prc genes are not essential for viability (20,21). However, proteomic analyses of the S. coelicolor prc null strain revealed a marked overproduction of proteins that mediate stress responses (21).…”

“…While the relevance of the Pup-proteasome system to the pathogenicity of M. tuberculosis has made it the focus of much attention, we and others (20,21) have been intrigued by the homologous system in Streptomyces bacteria. These actinobacteria are best known as producers of antibiotics and for their complex life cycle, during which both morphological differentiation and sporulation occur (22)(23)(24).…”

Molecular Regulation of Antibiotic Biosynthesis in Streptomyces

“…The targeting of proteins to proteasomes requires the conjugation of a small "Pup" (prokaryotic ubiquitin-like protein) tag to substrates (275). The Streptomyces 20S proteasome was first identified in 1998, and its functions were initially investigated in 2007 (278,282). A different protein profile was noticed in proteasome mutants of S. coelicolor, though no specific proteasome target was identified.…”