Distribution of positively charged amino acid residues in antimicrobial peptide epinecidin-1 is crucial for in vitro glioblastoma cytotoxicity and its underlying mechanisms

Persulfide, polysulfide and thiosulfate are examples of sulfane sulfur containing chemicals that play multiple functions in biological systems. Rhodaneses are widely present in all three kingdoms of life, which catalyze sulfur transfer among these sulfane sulfur-containing chemicals. The mechanism of how rhodaneses function is not well understood. Saccharomyces cerevisiae rhodanese 2 (RDL2) is involved in mitochondrial biogenesis and cell cycle control. Herein, we report a 2.47 Å resolution structure of RDL2 co-crystallized with thiosulfate (PDB entry: 6K6R). The presence of an extra sulfur atom Sδ, forming a persulfide bond with the Sγ atom of Cys106, was observed. Distinct from the persulfide groups in GlpE (PDB entry:1GMX) and rhobov (PDB entry:1BOI), the persulfide group of RDL2 is located in a peanut-like pocket of the neutral electrostatic field and is far away from positively charged amino acid residues of its active-site loop, suggesting no interaction between them. This finding suggests that the positively charged amino acid residues are not involved in the stabilization of the persulfide group. Activity assays indicate that the Arg111 of the active-site loop is critical for the sulfane sulfur transfer. In vitro assays indicate that Arg propels the thiosulfate decomposition. Thus, we propose that Arg can offer a hydrogen bond-rich, acidic-like microenvironment in RDL2 in which thiosulfate decomposes to release sulfane sulfur. Thr of the active-site loop of rhodaneses has the same functions as Arg. Our proposal may explain the catalyzing mechanism of rhodaneses.

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Positive Charges of Translocating Polypeptide Chain Retrieve an Upstream Marginal Hydrophobic Segment from the Endoplasmic Reticulum Lumen to the Translocon

Molecular Biology of the Cell ◽

10.1091/mbc.e09-12-1060 ◽

2010 ◽

Vol 21 (12) ◽

pp. 2045-2056 ◽

Cited By ~ 17

Author(s):

Hidenobu Fujita ◽

Yuichiro Kida ◽

Masatoshi Hagiwara ◽

Fumiko Morimoto ◽

Masao Sakaguchi

Keyword(s):

Endoplasmic Reticulum ◽

Amino Acid ◽

Membrane Proteins ◽

Polypeptide Chain ◽

Water Environment ◽

Amino Acid Residues ◽

Endoplasmic Reticulum Lumen ◽

Membrane Spanning ◽

Positively Charged

Positively charged amino acid residues are well recognized topology determinants of membrane proteins. They contribute to the stop-translocation of a polypeptide translocating through the translocon and to determine the orientation of signal sequences penetrating the membrane. Here we analyzed the function of these positively charged residues during stop-translocation in vitro. Surprisingly, the positive charges facilitated membrane spanning of a marginally hydrophobic segment, even when separated from the hydrophobic segment by 70 residues. In this case, the hydrophobic segment was exposed to the lumen, and then the downstream positive charges triggered the segment to slide back into the membrane. The marginally hydrophobic segment spanned the membrane, but maintained access to the water environment. The positive charges not only fix the hydrophobic segment in the membrane at its flanking position, but also have a much more dynamic action than previously realized.

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Oxytocin analogues with non-coded amino acid residues in position 8: [8-Neopentylglycine]oxytocin and [8-cycloleucine]oxytocin

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19872317 ◽

1987 ◽

Vol 52 (9) ◽

pp. 2317-2325 ◽

Cited By ~ 5

Author(s):

Jan Hlaváček ◽

Jan Pospíšek ◽

Jiřina Slaninová ◽

Walter Y. Chan ◽

Victor J. Hruby

Keyword(s):

Amino Acid ◽

Solid Phase Synthesis ◽

Solid Phase ◽

The Other ◽

Amino Acid Residues ◽

Phase Synthesis ◽

Other Hand ◽

Fragment Condensation

[8-Neopentylglycine]oxytocin (II) and [8-cycloleucine]oxytocin (III) were prepared by a combination of solid-phase synthesis and fragment condensation. Both analogues exhibited decreased uterotonic potency in vitro, each being about 15-30% that of oxytocin. Analogue II also displayed similarly decreased uterotonic potency in vivo and galactogogic potency. On the other hand, analogue III exhibited almost the same potency as oxytocin in the uterotonic assay in vivo and in the galactogogic assay.

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Synthesis of Fragments of the Vasoactive Intestinal Peptide (VIP) and Analysis of Their Residual Biological Activities

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19951229 ◽

1995 ◽

Vol 60 (7) ◽

pp. 1229-1235 ◽

Cited By ~ 2

Author(s):

Ivana Zoulíková ◽

Ivan Svoboda ◽

Jiří Velek ◽

Václav Kašička ◽

Jiřina Slaninová ◽

...

Keyword(s):

Amino Acid ◽

Biological Activities ◽

Residual Activity ◽

Detailed Examination ◽

Amino Acid Residues ◽

Linear Peptide ◽

Zone Electrophoresis ◽

Capillary Zone

The vasoactive intestinal (poly)peptide (VIP) is a linear peptide containing 28 amino acid residues, whose primary structure indicates a low metabolic stability. The following VIP fragments, as potential metabolites, and their analogues were prepared by synthesis on a solid: [His(Dnp)1]VIP(1-10), VIP(11-14), [D-Arg12]VIP(11-14), [Lys(Pac)15,21,Arg20]VIP(15-22), and VIP(23-28). After purification, the peptides were characterized by amino acid analysis, mass spectrometry, RP HPLC, and capillary zone electrophoresis. In some tests, detailed examination of the biological activity of the substances in vivo and in vitro gave evidence of a low, residual activity of some fragments, viz. a depressoric activity in vivo for [His(Dnp)1]VIP(1-10) and a stimulating activity for the release of α-amylase in vitro and in vivo for [Lys(Pac)15,21,Arg20]VIP(15-22) and VIP(23-28).

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Identifying and Characterizing a Novel Peritrophic Matrix Protein (MdPM-17) Associated With Antibacterial Response From the Housefly, Musca domestica (Diptera: Muscidae)

Journal of Insect Science ◽

10.1093/jisesa/ieaa135 ◽

2020 ◽

Vol 20 (6) ◽

Author(s):

Yu Wang ◽

Jinzhi Cheng ◽

Man Luo ◽

Jianwei Wu ◽

Guo Guo

Keyword(s):

Amino Acid ◽

Antimicrobial Peptide ◽

Musca Domestica ◽

Matrix Protein ◽

Binding Capacity ◽

Malpighian Tubule ◽

Peritrophic Membrane ◽

Distribution Analysis ◽

Peritrophic Matrix ◽

Amino Acid Residues

Abstract Peritrophic matrix/membrane (PM) critically prevents the midgut of insects from external invasion by microbes. The proteins in the peritrophic membrane are its major structural components. Additionally, they determine the formation and function of this membrane. However, the role of PM proteins in immune regulation is unclear. Herein, we isolated a novel PM protein (MdPM-17) from Musca domestica larvae. Further, the function of MdPM-17 in regulating host innate immunity was identified. Results showed that the cDNA of MdPM-17 full is 635 bp in length. Moreover, it consists of a 477-bp open reading frame encoding 158 amino acid residues. These amino acid residues are composed of two Chitin-binding type-2 domain (ChtBD2) and 19 amino acids as a signal peptide. Moreover, tissue distribution analysis indicates that MdPM-17 was enriched expressed in midgut, and moderate levels in the fat body, foregut, and malpighian tubule. Notably, MdPM-17 recombinant protein showed high chitin-binding capacity, thus belongs to the Class III PM protein group. MdPM-17 protein silencing via RNA interference resulted in the expression of antimicrobial peptide (defensin, cecropins, and diptericin) genes, and this occurred after oral inoculation with exogenous microbes Escherichia coli (Enterobacteriales:Enterobacteriaceae), Staphylococcus aureus (Bacillales:Staphylococcaceae), and Candida albicans (Endomycetales:Saccharomycetaceae)). Therefore, all the antimicrobial peptide (AMP) gene expression levels are high in MdPM-17-depleted larvae during microbial infection compared to controls. Consequently, these findings indicate that MdPM-17 protein is associated with the antibacterial response from the housefly.

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Engineering two mutants of cDNA-encoding G2 subunit of soybean glycinin capable of self-assembly in vitro and rich in methionine

Biologia ◽

10.2478/s11756-007-0097-1 ◽

2007 ◽

Vol 62 (4) ◽

Author(s):

Reda Sammour

Keyword(s):

Amino Acid ◽

Self Assembly ◽

Seed Quality ◽

Amino Acid Residues ◽

Methionine Residues

AbstractThe main goal of this work was to make the cDNA-encoding subunit G2 of soybean glycinin, capable of self-assembly in vitro and rich in methionine residues. Two mutants (pSP65/G4SacG2 and pSP65/G4SacG2HG4) were therefore constructed. The constructed mutants were successfully assembled in vitro into oligomers similar to those occurred in the seed. The successful self-assembly was due to the introduction of Sac fragment of Gy4 (the codons of the first 21 amino acid residues), which reported to be the key element in self-assembly into trimers. The mutant pSP65/G4SacG2HG4 included the acidic chain of Gy4 (HG4), which was previously molecularly modified to have three methionine residues. This mutant will be useful in the efforts to improve the seed quality.

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In Silico Prediction, Molecular Docking and Dynamics Studies of Steroidal Alkaloids of Holarrhena pubescens Wall. ex G. Don to Guanylyl Cyclase C: Implications in Designing of Novel Antidiarrheal Therapeutic Strategies

Molecules ◽

10.3390/molecules26144147 ◽

2021 ◽

Vol 26 (14) ◽

pp. 4147

Author(s):

Neha Gupta ◽

Saurav Kumar Choudhary ◽

Neeta Bhagat ◽

Muthusamy Karthikeyan ◽

Archana Chaturvedi

Keyword(s):

Molecular Docking ◽

Amino Acid ◽

Guanylyl Cyclase ◽

Extracellular Domain ◽

Enterotoxigenic Escherichia Coli ◽

Watery Diarrhea ◽

Guanylyl Cyclase C ◽

Amino Acid Residues ◽

Lead Compounds

The binding of heat stable enterotoxin (STa) secreted by enterotoxigenic Escherichia coli (ETEC) to the extracellular domain of guanylyl cyclase c (ECDGC-C) causes activation of a signaling cascade, which ultimately results in watery diarrhea. We carried out this study with the objective of finding ligands that would interfere with the binding of STa on ECDGC-C. With this view in mind, we tested the biological activity of a alkaloid rich fraction of Holarrhena pubescens against ETEC under in vitro conditions. Since this fraction showed significant antibacterial activity against ETEC, we decided to test the screen binding affinity of nine compounds of steroidal alkaloid type from Holarrhena pubescens against extracellular domain (ECD) by molecular docking and identified three compounds with significant binding energy. Molecular dynamics simulations were performed for all the three lead compounds to establish the stability of their interaction with the target protein. Pharmacokinetics and toxicity profiling of these leads demonstrated that they possessed good drug-like properties. Furthermore, the ability of these leads to inhibit the binding of STa to ECD was evaluated. This was first done by identifying amino acid residues of ECDGC-C binding to STa by protein–protein docking. The results were matched with our molecular docking results. We report here that holadysenterine, one of the lead compounds that showed a strong affinity for the amino acid residues on ECDGC-C, also binds to STa. This suggests that holadysenterine has the potential to inhibit binding of STa on ECD and can be considered for future study, involving its validation through in vitro assays and animal model studies.

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