Screening Peptide Inhibitors Using Phage Peptide Library with Isocitrate Lyase in Mycobacterium tuberculosis as Target

When devoured by macrophages,Mycobacterium tuberculosis remains persistent in macrophages and gains energy through the glyoxylate bypass to maintain its long-term existence in host cells.Therefore it is possible to stop persistent infections by interdicting the glyoxylate bypass in which the isocitrate lyase（ICL） is the key rate-limiting enzyme and a persistence factor.ICL is the target of anti-TB（TB：tubercular） drugs,which could screen ICL out and effectively inhibit the activity of ICL in Mycobacterium tuberculosis,and because of this,anti-TB drugs can be used to kill persistent Mycobacterium tuberculosis.In this study,the ICL gene of the Mycobacterium tuberculosis H37Rv was cloned successfully and recombinant protein with bioactivity was obtained through the enzyme characteristic appraisal.The specific activity of the recombined ICL is 24μmol·mg-1·min-1.The recombined ICL protein was used as the target,and phages which can specifically combine to ICL were screened in the phage 7 peptide library.According to the results of the ELISA and DNA sequence detection,eventually three 7-peptide chains were synthesized.Then the peptide chains were reacted with ICL,respectively,to detect their inhibitory effects on ICL.The results show that all the three 7-peptide chains possessed varying inhibitory effects on the activity of ICL.This study provided lead compounds for the research and development of new peptide anti-TB drugs.

Screening of TACE Peptide Inhibitors from Phage Display PeptideLibrary

Summary： To obtain the recombinant tumor necrosis factor-α converting enzyme （TACE） ectodomain and use it as a selective molecule for the screening of TACE peptide inhibitors, the cDNA coding catalytic domain （TS00） and full-length ectodomain （T1300） of TACE were amplified by RT-PCR, and the expres.sion plasmids were constructed by inserting T800 and T1300 into plasmid pET-28a and pET-28c respectively. The recombinant TS00 and T1300 were induced by IPTG, and SDS-PAGE and Western blotting analysis results revealed that TS00 and T1300 were highly expressed in the form of inclusion body. After Ni^2＋-NTA resin affinity chromatography, the recombinant proreins were used in the screening of TACE-binding peptides from phage display peptide library respectively. After 4 rounds of biopanning, the positive phage clones were analyzed by ELISA, competitive inhibition assay and DNA sequencing. A common amino acid sequence （TRWLVYFSRPYLVAT） was found and synthesized. The synthetic peptide could inhibit the TNF-α release from LPS-stimulated human peripheral blood mononuclear cells （PBMC） up to 60.3%. FACS analysis revealed that the peptide mediated the accumulation of TNF-α on the cell surface. These results demonstrate that the TACE binding peptide is an effective antagonist of TACE.

A pan-coronavirus peptide inhibitor prevents SARS-CoV-2 infection in mice by intranasal delivery

Coronaviruses(Co Vs)have brought serious threats to humans,particularly severe acute respiratory syndrome coronavirus 2(SARS-Co V-2),which continually evolves into multiple variants.These variants,especially Omicron,reportedly escape therapeutic antibodies and vaccines,indicating an urgent need for new antivirals with pan-SARS-Co V-2 inhibitory activity.We previously reported that a peptide fusion inhibitor,P3,targeting heptad repeated-1(HR1)of SARS-Co V-2 spike(S)protein,could inhibit viral infections.Here,we further designed multiple derivatives of the P3 based on structural analysis and found that one derivative,the P315V3,showed the most efficient antiviral activity against SARS-Co V-2 variants and several other sarbecoviruses,as well as other human-Co Vs(HCo Vs).P315V3 also exhibited effective prophylactic efficacy against the SARS-Co V-2 Delta and Omicron variants in mice via intranasal administration.These results suggest that P315V3,which is in PhaseⅡclinical trial,is promising for further development as a nasal pan-SARS-Co V-2 or pan-Co Vs inhibitor to prevent or treat CoV diseases.

Development of peptide inhibitors of HIV transmission

Treatment of HIV has long faced the challenge of high mutation rates leading to rapid development of resistance,with ongoing need to develop new methods to effectively fight the infection.Traditionally,early HIV medications were designed to inhibit RNA replication and protein production through small molecular drugs.Peptide based therapeutics are a versatile,promising field in HIV therapy,which continues to develop as we expand our understanding of key protein-protein interactions that occur in HIV replication and infection.This review begins with an introduction to HIV,followed by the biological basis of disease,current clinical management of the disease,therapeutics on the market,and finally potential avenues for improved drug development.

Development of a potent peptide inhibitor of estrogen receptor α

We have developed a facile N-terminus helix-nucleating strategy using an unnaturally tethered aspartic acid(TD strategy). Relatively weak nuclear translocation efficiency of TD PERM limits its further biological applications. A potent peptide inhibitor of estrogen receptor α(ER-α) with significantly increased cellular uptake and cellular distribution was developed by cell penetrating peptide attachment.The resulted peptide conjugate showed selective toxicity towards estrogen receptor positive cell lines and induced decreased transcription of estrogen receptor a downstream genes.

Screening of Peptide Inhibitors of TACE from a Phage Display Random 15-Peptide Library by Recombinant TACE Ectodomain

Tumor necrosis factor(TNF)-α-converting enzyme(TACE)is the major protease responsible for processing pro-TNF-αfrom membrane-anchored precursors to secreted TNF-α.In the present study,a 15-peptide library was used to identify potential TACE antagonists.To obtain the recombinant TACE ectodomain and to use it as a selective molecule for the screening of peptide inhibitors of TACE,cDNA coding for the catalytic domain(T800)and full-length ectodomain(T1300)of TACE were amplified by reverse transcription–polymerase chain reaction.The expression plasmid were constructed by inserting T800/T1300 into plasmid pET-28a/c respectively and were transformed into Escherichia coli BL21(DE3).Sodium dodecyl sulfate–polyacrylamide gel electrophoresis(SDSPAGE)andWestern blot analysis revealed that T800/T1300 were highly expressed in the form of an inclusion body induced by isopropylthiogalactoside.After Ni2+–NTA resin affinity chromatography,the purity of the recombinant T800/T1300 protein was more than 90%.T800 and T1300 proteins were used in the screening of T800/T1300-binding peptides from a phage display random 15-peptide library.After four rounds of biopanning,the positive phage clones were analyzed by enzyme-linked immunosorbent assay,competitive inhibition assay(ELESA),and DNA sequencing.A common amino acid sequence(TRWLVYFS RPYLVAT)was confirmed and synthesized.A synthetic peptide was shown to bind to TACE and to inhibit TNF-αrelease from lipopolysaccharide(LPS)-stimulated human peripheral blood mononuclear cells(PBMC)by up to 60.3%.Fluorescence-activated cell sorter(FACS)analysis revealed that the peptide mediated the accumulation of TNF-αon an LPS-stimulated PBMC surface.These results demonstrate that the TACE-binding peptide is an effective antagonist of TACE and that the deduced motif might be applied to the molecular design of anti-inflammatory drugs.

Microwave-assisted Solid-phase Synthesis, Biological Evaluation and Molecular Docking of Angiotensin I-converting Enzyme Inhibitors

Short peptides based on the tripeptides, Leu-Arg-Pro and Leu-Lys-Pro, were synthesized by microwave assisted solid-phase synthesis method, in order to make a search for potential inhibitors for angiotensin I-converting enzyme（ACE） with minimum side effects in the treatment of hypertension. One peptide with the sequence Leu-Arg-Pro-Phe-Phe shows the strongest inhibition towards ACE with an IC50 value of 0.26 μmol/L in vitro. The study of structure-activity relationship shows that the introduction of a bulky group into the N-terminal of this series of inhibitors may enlarge steric hindrance, resulting in the poor inhibitory activity towards ACE. The inhibitory activity decreased in turn when L-Pro, D-Pro or Ac6c was at the C-terminal respectively. The binding interaction between each of these inhibitors and testicular ACE（tACE） was performed by molecular docking. The results suggest that Leu-Arg-Pro-Phe-Phe mainly occupied the S1 subsite of tACE, and made contact with tACE via seven H-bonds. It appeared that the site on the peptide that bound with tACE was influenced by the configuration of the amino acid, L or D-form, at the C-terminal of the peptide.

Mechanism of Three Inhibitors of TACE in Blocking the Converting of pro-TNFα into sTNFα

The effects of inhibitors of TNFα converting enzyme (TACE) on TNFα secretion were studied to develop an approach to interfere inflammation processes. The HL-60 cell lines were stimulated in vitro with LPS intravenously for different time to establish the cellular model of inflammation and simultaneously induce in vivo inflammation animal model by LPS The cytotoxic effects of soluble TNFa were checked using MTT colorimetric method to determine the rate of cell proliferation. The level of expression of TACE was detected by using RT-PCR, FCM and immuno-histochemical technique respectively. It was found Chinese medicine Reduqing (RDQ) could inhibit the transcription of TNFa mRNA induced by LPS stimulation (P<0. 01, compared with the control). The anti-oligodeoxyribonucleotide (anti-ODN) of TNFα mRNA could inhibit 78. 9 % of TNFα secretion. The mimic peptides of TACE substrates with hydroxamine group showed potency in vivo and in vitro a-gainst converting of pro-TNFα. It was concluded that all the three types of TACE inhibitors can regulate the expression of TACE at different levels and inhibit sTNFα secretion, indicating TACE is a novel target for inflammation therapy.

A bifunctional vinyl-sulfonium tethered peptide induced by thio-Michael-type addition reaction

The modification and functionalization of peptides is of great significance in modern biotechnology and drug development. Here we report a highly reactive Michael-type warhead for the covalently modification of cysteine on peptide and protein. By installing a vinyl group onto a methionine residue of peptide,the produced vinyl sulfonium can be efficiently nucleophilic added by appropriate cysteine residue of this peptide, and thus yield a cyclized peptide. This peptide cyclization strategy was proven to exhibit improved cell penetration and good stability. Moreover, a peptide ligand bearing vinyl sulfonium could covalently bind to the cysteine in the target protein, indicating the potential of vinyl sulfonium as a novel warhead for developing covalent peptide inhibitor.

A Peptide Binder of E3 Ligase Adaptor SPOP Disrupts Oncogenic SPOP-Protein Interactions in Kidney Cancer Cells

The E3 ligase adaptor SPOP,overexpressed in the nucleus but frequently dislocated into the cytoplasm in all clear cell Renal Cell Carcinomas(ccRCC),serves as a regulatory hub to promote kidney cancer through the ubiquitination and degradation of multiple downstream cancer proteins.Recently,our identification of a selective small-molecule inhibitor of the SPOP-phosphatase and tensin homolog(PTEN)interaction has demonstrated that the oncogenic SPOP-protein interaction would be a druggable target specific to ccRCC therapy.To our knowledge,this is the first time such a small-molecule inhibitor has been developed.Herein,we have identified a peptide binder for the SPOP-MATH domain that disrupts the oncogenic SPOP-protein interactions in kidney cancer cells.Computational design and biophysical characterization yielded peptide Pep38 that binds to the MATH domain of SPOP and competes on PTEN-binding to SPOP in vitro.The X-ray complex structure reveals that the peptide binder features the following combination:one,a mimic of the native peptide binder and two,an additionalβ-strand motif in sequence,which could contribute to increased binding affinity.In order to improve cellular permeability,we fused Pep38 with the delivery peptide TAT to prepare peptide TAT38,which inhibits the endogenous substrate binding to SPOP and suppresses the proliferation of the ccRCC cells.Our identification of the peptide inhibitors for SPOP-protein interactions provides further validation that the oncogenic SPOP-signaling pathway in ccRCC could be a druggable target specifically applicable to the therapy of kidney cancers.

Targeting secret handshakes of biological processes for novel drug development

In multicellular organisms, several biological processes control the rise and fall of life. Different cell types communicate and co-operate in response to different stimulus through cell to cell signaling and regulate biologic processes in the cell/organism. Signaling in multicellular organism has to be made very secretly so that only the target cell responds to the signal. Of all the biomolecules, nature chose mainly proteins for secret delivery of information both inside and outside the cell. During cell signaling, proteins physically interact and shake hands for transfer of secret information by a phenomenon called as protein protein interactions （PPIs）. In both, extra and intracellular signaling processes PPIs play a crucial role. PPIs involved in cellular signaling are the primary cause for cell proliferation, differentiation, movement, metabolism, death and various other biological processes not mentioned here. These secret handshakes are very specific for specific functions. Any alterations/malfunctions in particular PPIs results in diseased condition. An overview of signaling pathways and importance of PPIs in cellular function and possibilities of targeting PPIs for novel drug development are discussed in this review.