Biology subjects

Hayouka, Z.

Publications and source records attributed to Hayouka, Z..

5 recordsLinked to original sources

bioRxiv2023

Nature-Inspired Peptide of MtDef4 C-terminus Tail Enables Protein Delivery in Mammalian Cells

Cell-penetrating peptides hold great promise as versatile tools for the intracellular delivery of therapeutic agents. Various peptides have originated from natural proteins with antimicrobial activity. In this study, we investigated the mammalian cell-penetrating properties of a 16-residue peptide derived from the C-terminus tail of the Medicago truncatula defensin protein, with the sequence GRCRHGFRRRCFCTTHC. We evaluated the ability of this peptide to penetrate multiple types of cells. Our results demonstrate that the peptide efficiently penetrates mammalian cells within minutes and at a sub-micromolar concentration. Moreover, upon N-terminal fusion to the fluorescent protein GFP, the peptide efficiently delivers the GFP into the cells. Despite its remarkable cellular penetration, the peptide has only a minor effect on cellular viability, making it a promising candidate for the development of a cell-penetrating peptide, with potential therapeutic applications.

cell biology↗

bioRxiv2023

Reactivating the complement system using peptidic bacterial labeling tag

The immune system plays a critical role in protecting the host against pathogens, including bacteria, viruses, and parasites. However, pathogens have evolved mechanisms to evade the immune system, for example by altering their surface proteins or by producing enzymes that can interfere with the immune response. These evasion strategies enable pathogens to escape detection and destruction by the immune system, which allows them to establish serious infections. Thus, there is a critical need for new strategies for developing antimicrobial agents. Here, we describe a novel strategy for targeting pathogens, by labeling them with a general peptide functioning as a bacterial binder, conjugated to a protein tag recognizable by the complement system, thereby activating the immune system against the target pathogen. To that end, we screened several pathogenic bacteria to find complement-resistant bacterial strain. A selected peptide binder was crosslinked with the C3b complement protein using glutaraldehyde. We show by an ELISA assay that the resulting complex binds the C5 complement protein with high affinity. We posited that by binding C5, this complex will be capable of initiating the alternative complement downstream proteolytic cascade, thereby inducing the formation of the membrane attack complex. Using this methodology, we were able to eradicate 90% of complement-resistant E. coli bacterial cells. By showing enhancement of complement sensitivity in complement-resistant pathogens, this work demonstrates the basis for new therapeutic approach capable of targeting pathogenic bacteria and activating the immune system against them.

microbiology↗

bioRxiv2022

Quorum sensing peptidic inhibitor rescue host immune system eradication: a novel QS infectivity mechanism

Subverting the host immune system is a major task for any given pathogen to assure its survival and proliferation. For the opportunistic human pathogen Bacillus cereus (Bc), immune evasion enables the establishment of potent infections. In various species of the Bc group, the pleiotropic regulator PlcR and its cognate cell-cell signaling peptide PapR7 regulates virulence genes expression in response to fluctuations in population density, i.e., a quorum-sensing (QS) system. However, how QS exerts its effects during infections, and whether PlcR confers the immune evading ability remain unclear. Herein, we report how interception of the QS communication in Bc obliterates the ability to control the host immune system. Here we designed a peptide-based QS inhibitor that suppresses PlcR-dependent virulence factor expression and attenuates Bc infectivity in mouse models. We demonstrate that the QS peptidic inhibitor blocks host immune system-mediated eradication by reducing the expression of PlcR-regulated major toxins. Our findings provide the first evidence that Bc infectivity is regulated by QS circuit mediated destruction of the host immunity, thus reveal a new strategy to limit Bc virulence and enhance host defense. This peptidic quorum-quenching agent constitutes readily accessible chemical tool for studying how other pathogen QS systems modulate host immunity and forms a basis for development of anti-infective therapeutics.

microbiology↗

bioRxiv2022

The C-terminal tail of CSNAP attenuates the CSN complex

Protein degradation is one of the essential mechanisms that enables reshaping of the proteome landscape in response to various stimuli. The largest E3 ubiquitin ligase family that targets proteins to degradation by catalyzing ubiquitnation is the cullin-RING ligases (CRL). Many of the proteins that are regulated by CRLs are central to tumorigenesis and tumour progression, and dysregulation of the CRL family is frequently associated with cancer. The CRL family comprises [~]300 complexes all of which are regulated by the COP9 signalosome complex (CSN). Therefore, the CSN is considered an attractive target for therapeutic intervention. Research efforts for targeted CSN inhibition have been directed towards inhibition of the complex enzymatic subunit, CSN5. Here, we have taken a fresh approach focusing on CSNAP, the smallest CSN subunit. Our results show that the C-terminal region of CSNAP is tightly packed within the CSN complex, in a groove formed by CSN3 and CSN8. We show that a 16 amino acid C-terminal peptide, derived from this CSN interacting region, can displace the endogenous CSNAP subunit from the complex. This, in turn, leads to a CSNAP null phenotype that attenuates CSN activity and consequently CRLs function. Overall, our findings emphasize the potential of a CSNAP-based peptide for CSN inhibition as a new therapeutic avenue.

biochemistry↗

bioRxiv2022

Combination treatment can hinder the evolution of resistance to antimicrobial peptides

Antibiotic resistant microbial pathogens are becoming a major threat to human health. Therefore, there is an urgent need to develop new alternatives to conventional antibiotics. One such promising alternative is antimicrobial peptides (AMPs), which are produced by virtually all organisms and typically inhibit bacteria via membrane disruption. However, previous studies demonstrated that bacteria can rapidly develop AMP resistance. Here, we study whether combination therapy, known to be able to inhibit the evolution of resistance to conventional antibiotics, can also hinder the evolution of AMP resistance. To do so, we evolved the opportunistic pathogen S. aureus in the presence of individual AMP, AMP pairs, and a combinatorial antimicrobial peptide library. Treatment with some AMP pair indeed hindered the evolution of resistance compared with individual AMPs. In particular, resistance to pairs was delayed when resistance to the individual AMPs came at a cost of impaired bacterial growth, and did not confer cross-resistance to other tested AMPs. The lowest level of resistance evolved during treatment with the combinatorial antimicrobial peptide library termed random antimicrobial peptide mixture, which contains more than a million different peptides. A better understanding of how AMP combinations affect the evolution of resistance is a crucial step in order to design resistant proof AMPs cocktails that will offer a sustainable treatment option for antibiotic resistant pathogens.

evolutionary biology↗