The Disordered C-Terminus of the Chaperone DnaK Increases the Competitive Fitness of Pseudomonas putida and Facilitates the Toxicity of GraT

Abstract

Chaperone proteins are crucial for proper protein folding and quality control, especially when cells encounter stress caused by non-optimal temperatures. DnaK is one of such essential chaperones in bacteria. Although DnaK has been well characterized, the function of its intrinsically disordered C-terminus has remained enigmatic as the deletion of this region has been shown to either enhance or reduce its protein folding ability. We have shown previously that DnaK interacts with toxin GraT of the GraTA toxin-antitoxin system in Pseudomonas putida. Interestingly, the C-terminal truncation of DnaK was shown to alleviate GraT-caused growth defects. Here, we aim to clarify the importance of DnaK in GraT activity. We show that DnaK increases GraT toxicity, and particularly important is the negatively charged motif in the DnaK C-terminus. Given that GraT has an intrinsically disordered N-terminus, the assistance of DnaK is probably needed for re-modelling the toxin structure. We also demonstrate that the DnaK C-terminal negatively charged motif contributes to the competitive fitness of P. putida at both high and optimal growth temperatures. Thus, our data suggest that the disordered C-terminal end of DnaK enhances the chaperone functionality.

Recombinant Actifensin and Defensin-d2 Induce Critical Changes in the Proteomes of Multidrug-Resistant Pseudomonas aeruginosa and Candida albicans

“…5b ). Downregulated chaperone protein DnaK, which plays a crucial role in DNA replication and repair and protein biogenesis ( 55 ), interacted linearly with 50S ribosomal protein L1 (upregulated), while the upregulated 30S ribosomal protein S6 interacted linearly with downregulated carbomyl-phosphate synthase large chain, an essential protein in amino acid metabolism. The up-down effects seen in the ribosomal and metabolic proteins present a scenario of overexpression of the ribosomal proteins (in order to synthesize essential proteins) in response to stress induced by the recombinant peptides.…”

Allosteric Inter-Domain Contacts in Bacterial Hsp70 Are Located in Regions That Avoid Insertion and Deletion Events

“…Hsp70 contains an unstructured C-terminal tail with lengths of high variability. A potential function of this unstructured tail has recently emerged in biochemical studies [ 6 , 7 , 8 ]. For the essential heat shock response of Hsp70, the allostery between protein substrate binding and ATP hydrolysis is vital.…”