DnaK and GroEL are induced in response to antibiotic and heat shock in Acinetobacter baumannii

Abstract

We studied the expression of DnaK and GroEL in Acinetobacter baumannii cells (strains ATCC 19606 and RS4) under stress caused by heat shock or antibiotics. A Western blot assay showed that DnaK and GroEL levels increased transiently more than 2-fold after exposure of bacterial cells to heat shock for 20 min at 50 6C. Heat induction of DnaK and GroEL was blocked completely when an inhibitor of transcription, rifampicin, was added 1 min before a temperature upshift to 50 6C, suggesting that the induction of these chaperones depends on transcription. A. baumannii cells pretreated at 45 6C for 30 min were better able to survive at 50 6C for 60 min than cells pretreated at 37 6C, indicating that A. baumannii is able to acquire thermotolerance. DnaK and GroEL were successfully induced in cells pre-incubated with a subinhibitory concentration of streptomycin. Moreover, bacterial cells pretreated for 30 min at 45 6C were better able to survive streptomycin exposure than cells pretreated at physiological temperatures. DnaK expression was upregulated in a multidrug-resistant strain of A. baumannii (RS4) in the presence of different antimicrobials (ampicillin+sulbactam, cefepime, meropenem and sulphamethoxazole+ trimethoprim). This study is to the best of our knowledge the first to show that A. baumannii DnaK and GroEL could play an important role in the stress response induced by antibiotics.

Deciphering the Magainin Resistance Process of Escherichia coli Strains in Light of the Cytosolic Proteome

“…The upregulation of chaperones DnaK and GroEL has been further observed in cell stress responses, such as heat shock stress and antibiotic presence, where some association with antibiotic resistance has been established (11). In this work, we have also observed alterations in DnaK and GroEL patterns of expression in the metabolism of resistant strains in a nonstress environment.…”

Proteomic profiling of Rhizobium tropiciPRF 81: identification of conserved and specific responses to heat stress

“…As described for E. coli [52] , Bacillus cereus [53] and Acinetobacter baumannii [54], in R. tropici PRF 81 the molecular chaperone GroEL was up-regulated under high temperature. The differential expression of GroEL is critical to thermotolerance, since the chaperone can routinely rescue more than 80% of a denatured protein population [55].…”

Chaperonins Fight Aminoglycoside-induced Protein Misfolding and Promote Short-term Tolerance in Escherichia coli

“…Previous reports showed that GroEL/GroES up-regulation during aminoglycoside induced stress in different bacteria (8,18). Considering these observations, it seems likely that the MGM100 strain is violently impacted by aminoglycosides during arabinose omission, even if inhibition of GroEL/GroES expression leads to only limited depletion, because the natural response involving up-regulation of GroEL/GroES has been disabled.…”

“…Similar findings have been reported for E. coli, implying a response to misfolded proteins following aminoglycoside exposure (3). The aminoglycoside antibiotic kanamycin has been reported to induce several heat shock proteins, including GroEL, GroES, and DnaK in E. coli (7), and streptomycinincreased expression of heat shock proteins DnaK (Hsp70) and GroEL (Hsp60) in the opportunistic human pathogen Acinetobacter baumannii (8), consistent with aminoglycoside damage triggering protein misfolding. Whether these chaperones provide protection against exposure to aminoglycosides has not previously been investigated.…”

“…GroEL/ GroES overexpression also partly complements folding of wildtype GFP (15), as well as other GFP mutants (9). Like GroEL/ GroES (16), DnaK/DnaJ/GrpE shows a broad substrate spectrum (17) and forms part of the heat shock response that is induced upon aminoglycoside treatment (3,8). We cotransformed MG1655 with compatible GFP and GroEL/GroES or DnaK/DnaJ/GrpE expression plasmids and measured GFP folding as described above.…”