It is essential to acknowledge the efforts made thus far to manage or eliminate various disease burden faced by humankind. However, the rising global trends of the so-called incurable diseases continue to put pressure on Pharma industries and other drug discovery platforms. In the past, drugs with more than one target were deemed as undesirable options with interest being on the one-drug-single target. Despite the successes of the single-target drugs, it is currently beyond doubt that these drugs have limited efficacy against complex diseases in which the pathogenesis is dependent on a set of biochemical events and several bioreceptors operating concomitantly. Different approaches have thus been proposed to come up with effective drugs to combat even the complex diseases. In the past, the focus was on producing drugs from screening plant compounds; today, we talk about combination therapy and multi-targeting drugs. The multi-target drugs have recently attracted much attention as promising tools to fight against most challenging diseases, and thus a new research focus area. This review will discuss the potential impact of multi-target drug approach on various complex diseases with focus on malaria, tuberculosis (TB), diabetes and neurodegenerative diseases as the main representatives of multifactorial diseases. We will also discuss alternative ideas to solve the current problems bearing in mind the fourth industrial revolution on drug discovery.

Heat shock proteins (Hsps) play an important role in the development and pathogenicity of malaria parasites. One of the most prominent functions of Hsps is to facilitate the folding of other proteins. Hsps are thought to play a crucial role when malaria parasites invade their host cells and during their subsequent development in hepatocytes and red blood cells. It is thought that Hsps maintain proteostasis under the unfavourable conditions that malaria parasites encounter in the host environment. Although heat shock protein 70 (Hsp70) is capable of independent folding of some proteins, its functional cooperation with heat shock protein 90 (Hsp90) facilitates folding of some proteins such as kinases and steroid hormone receptors into their fully functional forms. The cooperation of Hsp70 and Hsp90 occurs through an adaptor protein called Hsp70-Hsp90 organising protein (Hop). We previously characterised the Hop protein from Plasmodium falciparum (PfHop). We observed that the protein co-localised with the cytosol-localised chaperones, PfHsp70-1 and PfHsp90 at the blood stages of the malaria parasite. In the current study, we demonstrated that PfHop is a stress-inducible protein. We further explored the direct interaction between PfHop and PfHsp70-1 using far Western and surface plasmon resonance (SPR) analyses. The interaction of the two proteins was further validated by co-immunoprecipitation studies. We observed that PfHop and PfHsp70-1 associate in the absence and presence of either ATP or ADP. However, ADP appears to promote the association of the two proteins better than ATP. In addition, we investigated the specific interaction between PfHop TPR subdomains and PfHsp70-1/ PfHsp90, using a split-GFP approach. This method allowed us to observe that TPR1 and TPR2B subdomains of PfHop bind preferentially to the C-terminus of PfHsp70-1 compared to PfHsp90. Conversely, the TPR2A motif preferentially interacted with the C-terminus of PfHsp90. Finally, we observed that recombinant PfHop occasionally eluted as a protein species of twice its predicted size, suggesting that it may occur as a dimer. We conducted SPR analysis which suggested that PfHop is capable of self-association in presence or absence of ATP/ADP. Overall, our findings suggest that PfHop is a stress-inducible protein that directly associates with PfHsp70-1 and PfHsp90. In addition, the protein is capable of self-association. The findings suggest that PfHop serves as a module that brings these two prominent chaperones (PfHsp70-1 and PfHsp90) into a functional complex. Since PfHsp70-1 and PfHsp90 are essential for parasite growth, findings from this study are important towards the development of possible antimalarial inhibitors targeting the cooperation of these two chaperones.

Heat shock protein 70 (Hsp70) is a molecular chaperone that plays an important role in cellular proteostasis. Hsp70s are also implicated in the survival and pathogenicity of malaria parasites. The main agent of malaria, Plasmodium falciparum, expresses six Hsp70s. Of these, two (PfHsp70-1 and PfHsp70-z) localize to the parasite cytosol. Previously conducted gene knockout studies suggested that PfHsp70-z is essential, and it has been demonstrated that small-molecule inhibitors targeting PfHsp70-1 cause parasite death. For this reason, both PfHsp70-1 and PfHsp70-z are potential antimalarial targets. Two cyclic lipopeptides, colistin and polymyxin B (PMB), have been shown to bind another heat shock protein, Hsp90, inhibiting its chaperone function. In the current study, we investigated the effect of PMB on the structure–function features of PfHsp70-1 and PfHsp70-z. Using surface plasmon resonance analysis, we observed that PMB directly interacts with both PfHsp70-1 and PfHsp70-z. In addition, using circular dichroism spectrometric analysis combined with tryptophan fluorescence measurements, we observed that PMB modulated the secondary and tertiary structures of Hsp70. Furthermore, PMB inhibited the basal ATPase activity and chaperone function of the two Hsp70s. Our findings suggest that PMB associates with Hsp70 to inhibit its function. In light of the central role of Hsp70 in cellular proteostasis and its essential role in the development of malaria parasites in particular, our findings expand the library of small-molecule inhibitors that target this medically important class of molecular chaperones.

Enzymes play a powerful role as catalysts with high specificity and activity under mild environmental conditions. Significant hurdles, such as reduced solubility, reduced shelf‐life, aggregate formation, and toxicity, are still ongoing struggles that scientists come across when purifying recombinant proteins. Over the past three decades, PEGylation techniques have been utilized to significantly overcome low solubility; increased protein stability, shelf‐life, and bioactivity; and prevented protein aggregate formation. This review seeks to highlight the impact of PEG‐based formulations that are significantly utilized to obtain favourable protein physiochemical properties. The authors further discuss other techniques that can be employed such as coexpression studies and nanotechnology‐based skills to obtaining favourable protein physiochemical properties.