Identification and characterization of a bactericidal and proapoptotic peptide from cycas revoluta seeds with DNA binding properties

Abstract

Nowadays, novel pharmacies have been screened from plants. Among them are the peptides, which show multiple biotechnological activities. In this report, a small peptide (Ala-Trp-Lys-Leu-Phe-Asp-Asp-Gly-Val) with a molecular mass of 1,050 Da was purified from Cycas revoluta seeds by using reversed-phase liquid chromatography. This peptide shows clear deleterious effects against human epidermoid cancer (Hep2) and colon carcinoma cells (HCT15). It caused inhibition of cancer cell proliferation and further disruption of nucleosome structures, inducing apoptosis by direct DNA binding. A remarkable antibacterial activity was also observed in this same peptide. Nevertheless, no significant lysis of normal RBC cells was observed in the presence of peptide. Additionally, an acetylation at the N-termini portion is able to reduce both activities. Bioinformatics tools were also utilized for construction of a three-dimensional model showing a single amphipathic helix. Since in vitro binding studies show that the target of this peptide seems to be DNA, theoretical docking studies were also performed to better understand the interaction between peptide and nucleic acids and also to shed some light on the acetyl group role. Firstly, binding studies showed that affinity contacts basically occur due to electrostatic attraction. The complex peptide-ssDNA was clearly oriented by residues Ala(1), Lys(3), and Asp(6), which form several hydrogen bonds that are able to stabilize the complex. When acetyl was added, hydrogen bonds are broken, reducing the peptide affinity. In summary, it seems that information here provided could be used to design a novel derivative of this peptide which a clear therapeutic potential.

Structural and Functional Characterization of a Multifunctional Alanine-Rich Peptide Analogue from Pleuronectes americanus

“…Most bactericidal activities have been related to cationic residues in the literature [9], [61]. Despite the fact that arginine and lysine cationic residues seem to have an important role for antimicrobial activity, Pa -MAP is devoid of these residues, presenting mostly hydrophobic amino acid residues with one histidine and one aspartic acid residue located in the N-termini region.…”

Anionic Host Defence Peptides from the Plant Kingdom: Their Anticancer Activity and Mechanisms of Action

“…It has previously been shown that HDPs were present in leaf extracts of Cycas revoluta from the Cycadaceae family [29] and more recently, Cr-ACP1 (net charge -1), was identified in seeds of the plant ( Table 1) [30]. The peptide was found to have selective toxicity towards human cells from colon carcinoma (HCT15) and epidermoid cancer (Hp2) with IC 50 values that were 1.5 mM and 0.6 mM respectively.…”

“…1). Further studies on Cr-ACP1 led to the suggestion that the anticancer action of the peptide utilised anti-proliferative mechanisms involving the binding of Cr-ACP1 to DNA, thereby inducing cell cycle arrest in the G0-G1 phase and the initiation of apoptotic mechanisms of cell death [30]. Cn-AMP2 (net charge -1) is an antibacterial peptide that was first identified in green coconut water, which is the clear liquid inside young coconuts from Cocos nucifera of the Arecaceae and a popular drink in Tropical Asia and Latin America ( Table 1) [34].…”

Cytotoxic potency of self-assembled Ruthenium(II)-NHC complexes with pincer type 2, 6-bis(N-methylimidazolylidene/benzimidazolylidene)pyrazine ligands

“…The cells were cultured as monolayers in MEM medium supplemented with 10% (v/v) heat-inactivated fetal bovine serum and antibiotics, and incubated at 37°C in a humidified atmosphere of 95% air and 5% CO 2 following Mandal et al 2012. [33] In brief, cells were plated in a 96-well flat-bottomed plate and allowed to attach to the culture surface overnight. On the next day, the broth was aspirated off, washed with PBS (1X) buffer and 200 µL of each complex-containing (0-100 μM) medium were separately added in triplicates.…”