Investigating the effect of the inhibitory peptide on L.monocytogenes cell invasion: an in silico and in vitro study

AIMS

L.monocytogenes monocytogenes is an omnipresent bacterium that causes a fatal food-borne illness, listeriosis. The connection of this bacterium to E-cadherin through internalin A plays a significant role in the internalization of the bacteria. In this study, this interaction has been investigated for the design of an inhibitory peptide.

METHODS

The interaction of the proteins involved in the entry of bacteria was evaluated by molecular docking. According to their interactions, an inhibitory peptide was designed to bind to internalin A by server peptiderive. Its effects on L.monocytogenes invasion on the Caco-2 cell line and biofilm formation were also assessed.

FINDINGS

Docking results showed that the peptide has a high affinity for binding to Internalin A. The synthesized peptide at a concentration of 64 µg/ml inhibited 80% of the invasion of L.monocytogenes into the Caco-2 cell line. Furthermore, the studied peptide at the highest concentration had a slight inhibitory effect on biofilm formation.

CONCLUSION

These results reveal that short polypeptides can impede the invasion of target cells by L. monocytogenes in vitro and could be advantageous as restoring agents in vivo.

Human tau accumulation promotes glycogen synthase kinase-3β acetylation and thus upregulates the kinase: A vicious cycle in Alzheimer neurodegeneration

BACKGROUND

Glycogen synthase kinase-3β (GSK-3β) is one of the most effective kinases in promoting tau hyperphosphorylation and accumulation in Alzheimer's disease (AD). However, it is not clear how GSK-3β activity is regulated during AD progression.

METHODS

We firstly used mass spectrometry to identify the acetylation site of GSK-3β, and then established the cell and animal models of GSK-3β acetylation. Next, we conducted molecular, cell biological and behavioral tests. Finally, we designed a peptide to test whether blocking tau-mediated GSK-3β acetylation could be beneficial to AD.

FINDINGS

We found that GSK-3β protein levels increased in the brains of AD patients and the transgenic mice. Overexpressing tau increased GSK-3β protein level with increased acetylation and decreased ubiquitination-related proteolysis. Tau could directly acetylate GSK-3β at K15 both in vitro and in vivo. K15-acetylation inhibited ubiquitination-associated proteolysis of GSK-3β and changed its activity-dependent phosphorylation, leading to over-activation of the kinase. GSK-3β activation by K15-acetylation in turn exacerbated the AD-like pathologies. Importantly, competitively inhibiting GSK-3β K15-acetylation by a novel-designed peptide remarkably improved cognitive impairment and the AD-like pathologies in 3xTg-AD mice.

INTERPRETATION

Tau can directly acetylate GSK-3β at K15 which reveals a vicious cycle between tau hyperphosphorylation and GSK-3β activation.

FUNDING

This study was supported in parts by grants from Science and Technology Committee of China (2016YFC1305800), Hubei Province (2018ACA142), Natural Science Foundation of China (91949205, 82001134, 31730035, 81721005), Guangdong Provincial Key S&T Program (018B030336001).

Sequence and structure-based peptides as potent amyloid inhibitors: A review

Misfolded and natively disordered globular proteins tend to aggregate together in an interwoven fashion to form fibrous, proteinaceous deposits referred to as amyloid fibrils. Formation and deposition of such insoluble fibrils are the characteristic features of a broad group of diseases, known as amyloidosis. Some of these proteins are known to cause several degenerative disorders in humans, such as Amyloid-Beta (Aβ) in Alzheimer's disease (AD), human Islet Amyloid Polypeptide (hIAPP, amylin) in type 2 diabetes, α-synuclein (α-syn) in Parkinson's disease (PD) and so on. The fact that these proteins do not share any significant sequence or structural homology in their native states make therapy quite challenging. However, it is observed that aggregation-prone proteins and peptides tend to adopt a similar type of secondary structure during the formation of fibrils. Rationally designed peptides can be a potent inhibitor that has been shown to disrupt the fibril structure by binding specifically to the amyloidogenic region(s) within a protein. The following review will analyze the inhibitory potency of both sequence-based and structure-based small peptides that have been shown to inhibit amyloidogenesis of proteins such as Aβ, human amylin, and α-synuclein.

Computational identification of self-inhibitory peptides from white spot syndrome virus envelope protein VP28

Since effective chemotherapeutics or preventive measures are still unavailable, finding feasible approaches against white spot syndrome virus (WSSV) has always been the vital subject in shrimp farming field. Envelope proteins are the ideal targets for antiviral strategies development due to their indispensable roles in virus entry, and inhibitory peptides targeting them have been proved to be promising in blocking virus infection. In this study, the Wimley-White interfacial hydrophobicity scale (WWIHS) in combination with known structural data was applied to identify potential inhibitory peptides that targeted the envelope protein VP28 of WSSV. Results showed that two potential inhibitory peptides were identified, one of which exhibited not only obvious antiviral activity, but also broad-spectrum antimicrobial activity. The inhibitory peptide identified here can serve as a lead compound for anti-WSSV strategies development.