Design strategies for positively charged endolysins: Insights into Artilysin development

Endolysins are bacteriophage-encoded enzymes that can specifically degrade the peptidoglycan layer of bacterial cell wall, making them an attractive tool for the development of novel antibacterial agents. The use of genetic engineering techniques for the production and modification of endolysins offers the opportunity to customize their properties and activity against specific bacterial targets, paving the way for the development of personalized therapies for bacterial infections. Gram-negative bacteria possess an outer membrane that can hinder the action of recombinantly produced endolysins. However, certain endolysins are capable of crossing the outer membrane by virtue of segments that share properties resembling those of cationic peptides. These regions increase the affinity of the endolysin towards the bacterial surface and assist in the permeabilization of the membrane. In order to improve the bactericidal effectiveness of endolysins, approaches have been implemented to increase their net charge, including the development of Artilysins containing positively charged amino acids at one end. At present, there are no specific guidelines outlining the steps for implementing these modifications. There is an ongoing debate surrounding the optimal location of positive charge, the need for a linker region, and the specific amino acid composition of peptides for modifying endolysins. The aim of this study is to provide clarity on these topics by analyzing and comparing the most effective modifications found in previous literature.The authors are indebted to Agencia Española de Investigación for the granted project (PID2019-107298RB-C21/AEI/10.13039/501100011033 to EGF and AA and PID2019-107298RB-C22/AEI/10.13039/501100011033 to NFM), to Marató de TV3 foundation (grant 201812-30-31-32-33) and to AGAUR for project 2021 SGR 01552. The authors are also indebted to the CERCA Program (Generalitat de Catalunya) and European Social Fund for supporting our research. JVCT is supported with a Margarita Salas grant for the training of young doctoral graduates (722713).info:eu-repo/semantics/publishedVersio

Design strategies for positively charged endolysins : Insights into Artilysin development

Altres ajuts: acords transformatius de la UABEndolysins are bacteriophage-encoded enzymes that can specifically degrade the peptidoglycan layer of bacterial cell wall, making them an attractive tool for the development of novel antibacterial agents. The use of genetic engineering techniques for the production and modification of endolysins offers the opportunity to customize their properties and activity against specific bacterial targets, paving the way for the development of personalized therapies for bacterial infections. Gram-negative bacteria possess an outer membrane that can hinder the action of recombinantly produced endolysins. However, certain endolysins are capable of crossing the outer membrane by virtue of segments that share properties resembling those of cationic peptides. These regions increase the affinity of the endolysin towards the bacterial surface and assist in the permeabilization of the membrane. In order to improve the bactericidal effectiveness of endolysins, approaches have been implemented to increase their net charge, including the development of Artilysins containing positively charged amino acids at one end. At present, there are no specific guidelines outlining the steps for implementing these modifications. There is an ongoing debate surrounding the optimal location of positive charge, the need for a linker region, and the specific amino acid composition of peptides for modifying endolysins. The aim of this study is to provide clarity on these topics by analyzing and comparing the most effective modifications found in previous literature

Side effects of chaperone gene co-expression in recombinant protein production

Insufficient availability of molecular chaperones is observed as a major bottleneck for proper protein folding in recombinant protein production. Therefore, co-production of selected sets of cell chaperones along with foreign polypeptides is a common approach to increase the yield of properly folded, recombinant proteins in bacterial cell factories. However, unbalanced amounts of folding modulators handling folding-reluctant protein species might instead trigger undesired proteolytic activities, detrimental regarding recombinant protein stability, quality and yield. This minireview summarizes the most recent observations of chaperone-linked negative side effects, mostly focusing on DnaK and GroEL sets, when using these proteins as folding assistant agents. These events are discussed in the context of the complexity of the cell quality network and the consequent intricacy of the physiological responses triggered by protein misfolding

Microbial factories for recombinant pharmaceuticals

Most of the hosts used to produce the 151 recombinant pharmaceuticals so far approved for human use by the Food and Drug Administration (FDA) and/or by the European Medicines Agency (EMEA) are microbial cells, either bacteria or yeast. This fact indicates that despite the diverse bottlenecks and obstacles that microbial systems pose to the efficient production of functional mammalian proteins, namely lack or unconventional post-translational modifications, proteolytic instability, poor solubility and activation of cell stress responses, among others, they represent convenient and powerful tools for recombinant protein production. The entering into the market of a progressively increasing number of protein drugs produced in non-microbial systems has not impaired the development of products obtained in microbial cells, proving the robustness of the microbial set of cellular systems (so far Escherichia coli and Saccharomyces cerevisae) developed for protein drug production. We summarize here the nature, properties and applications of all those pharmaceuticals and the relevant features of the current and potential producing hosts, in a comparative wa

Effect of the DnaK chaperone on the conformational quality of JCV VP1 virus-like particles produced in Escherichia coli

Altres ajuts: CIBER de Bioingeniería, Biomateriales y Nanomedicina ; VI National R&D&i Plan 2008-2011 ; Iniciativa Ingenio 2010 ; Consolider Program ; CIBER Actions ; Instituto de Salud Carlos III ; European Regional Development FundProtein nanoparticles such as virus-like particles (VLPs) can be obtained by recombinant protein production of viral capsid proteins and spontaneous self-assembling in cell factories. Contrarily to infective viral particles, VLPs lack infective viral genome while retaining important viral properties like cellular tropism and intracellular delivery of internalized molecules. These properties make VLPs promising and fully biocompatible nanovehicles for drug delivery. VLPs of human JC virus (hJCV) VP1 capsid protein produced in Escherichia coli elicit variable hemagglutination properties when incubated at different NaCl concentrations and pH conditions, being optimal at 200 mM NaCl and at pH range between 5.8 and 7.5. In addition, the presence or absence of chaperone DnaK in E. coli cells influence the solubility of recombinant VP1 and the conformational quality of this protein in the VLPs. The hemagglutination ability of hJCV VP1 VLPs contained in E. coli cell extracts can be modulated by buffer composition in the hemagglutination assay. It has been also determined that the production of recombinant hJCV VP1 in E. coli is favored by the absence of chaperone DnaK as observed by Western Blot analysis in different E. coli genetic backgrounds, indicating a proteolysis targeting role for DnaK. However, solubility is highly compromised in a DnaK(-) E. coli strain suggesting an important role of this chaperone in reduction of protein aggregates. Finally, hemagglutination efficiency of recombinant VP1 is directly related to the presence of DnaK in the producing cells

Towards Protein-Based Viral Mimetics for Cancer Therapies

High resistance and recurrence rates, along with elevated drug clearance, compel the use of maximum tolerated drug doses in cancer therapy, resulting in high-grade toxicities and limited clinical applicability. Promoting active drug accumulation in tumor tissues would minimize such issues and improve therapeutic outcomes. A new class of therapeutic drugs suitable for the task has emerged based on the concept of virus-mimetic nanocarriers, or 'artificial viruses.' Among the spectrum of materials under exploration in nanocarrier research, proteins offer unparalleled structural and functional versatility for designing viruslike molecular vehicles. By exhibiting 'smart' functions and biomimetic traits, protein-based nanocarriers will be a step ahead of the conventional drug-protein conjugates already in the clinics in ensuring efficient delivery of passenger antitumor drugs

Intracellular trafficking of a dynein-based nanoparticle designed for gene delivery

The success of viruses in the delivery of the viral genome to target cells relies on the evolutionary selection of protein-based domains able to hijack the intermolecular interactions through which cells respond to intra- and extracellular stimuli. In an effort to mimic viral infection capabilities during non-viral gene delivery, a modular recombinant protein named T-Rp3 was recently developed, containing a DNA binding domain, a dynein molecular motor interacting domain, and a TAT-derived transduction domain. Here, we analyzed at the microscopic level the mechanisms behind the cell internalization and intracellular trafficking of this highly efficient modular protein vector. We found that the protein has the ability to self-assemble in discrete protein nanoparticles resembling viral capsids, to bind and condense plasmid DNA (pDNA), and to interact with eukaryotic cell membranes. Confocal and single particle tracking assays performed on living HeLa cells revealed that the T-Rp3 nanoparticles promoted an impressive speed of cellular uptake and perinuclear accumulation. Finally, the protein demonstrated to be a versatile vector, delivering siRNA at efficiencies comparable to Lipofectamine™. These results demonstrate the high potential of recombinant modular proteins with merging biological functions to fulfill several requirements needed to obtain cost-effective non-viral vectors for gene-based therapies

Biological activities of histidine-rich peptides; merging biotechnology and nanomedicine

Histidine-rich peptides are commonly used in recombinant protein production as purification tags, allowing the one-step affinity separation of the His-tagged proteins from the extracellular media or cell extracts. Genetic engineering makes feasible the post-purification His-tag removal by inserting, between the tag and the main protein body, a target site for trans-acting proteases or a self-proteolytic peptide with regulatable activities. However, for technical ease, His tags are often not removed and the fusion proteins eventually used in this form. In this commentary, we revise the powerful biological properties of histidine-rich peptides as endosomolytic agents and as architectonic tags in nanoparticle formation, for which they are exploited in drug delivery and other nanomedical applications. These activities, generally unknown to biotechnologists, can unwillingly modulate the functionality and biotechnological performance of recombinant proteins in which they remain trivially attached

BBB-targeting, protein-based nanomedicines for drug and nucleic acid delivery to the CNS

The increasing incidence of diseases affecting the central nervous system (CNS) demands the urgent development of efficient drugs. While many of these medicines are already available, the Blood Brain Barrier and to a lesser extent, the Blood Spinal Cord Barrier pose physical and biological limitations to their diffusion to reach target tissues. Therefore, efforts are needed not only to address drug development but specially to design suitable vehicles for delivery into the CNS through systemic administration. In the context of the functional and structural versatility of proteins, recent advances in their biological fabrication and a better comprehension of the physiology of the CNS offer a plethora of opportunities for the construction and tailoring of plain nanoconjugates and of more complex nanosized vehicles able to cross these barriers. We revise here how the engineering of functional proteins offers drug delivery tools for specific CNS diseases and more transversally, how proteins can be engineered into smart nanoparticles or 'artificial viruses' to afford therapeutic requirements through alternative administration routes