1
|
Katoh T, Suga H. Translation initiation with exotic amino acids using EF-P-responsive artificial initiator tRNA. Nucleic Acids Res 2023; 51:8169-8180. [PMID: 37334856 PMCID: PMC10450175 DOI: 10.1093/nar/gkad496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 05/10/2023] [Accepted: 06/17/2023] [Indexed: 06/21/2023] Open
Abstract
Translation initiation using noncanonical initiator substrates with poor peptidyl donor activities, such as N-acetyl-l-proline (AcPro), induces the N-terminal drop-off-reinitiation event. Thereby, the initiator tRNA drops-off from the ribosome and the translation reinitiates from the second amino acid to yield a truncated peptide lacking the N-terminal initiator substrate. In order to suppress this event for the synthesis of full-length peptides, here we have devised a chimeric initiator tRNA, referred to as tRNAiniP, whose D-arm comprises a recognition motif for EF-P, an elongation factor that accelerates peptide bond formation. We have shown that the use of tRNAiniP and EF-P enhances the incorporation of not only AcPro but also d-amino, β-amino and γ-amino acids at the N-terminus. By optimizing the translation conditions, e.g. concentrations of translation factors, codon sequence and Shine-Dalgarno sequence, we could achieve complete suppression of the N-terminal drop-off-reinitiation for the exotic amino acids and enhance the expression level of full-length peptide up to 1000-fold compared with the use of the ordinary translation conditions.
Collapse
Affiliation(s)
- Takayuki Katoh
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiroaki Suga
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| |
Collapse
|
2
|
Varnava KG, Edwards PJB, Cameron AJ, Harjes E, Sarojini V. Cyclic peptides bearing the d-Phe-2-Abz turn motif: Structural characterization and antimicrobial potential. J Pept Sci 2020; 27:e3291. [PMID: 33283398 DOI: 10.1002/psc.3291] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/07/2020] [Accepted: 10/14/2020] [Indexed: 11/10/2022]
Abstract
The effect on secondary structure and antimicrobial activity of introducing different cyclic constraints in linear β-hairpin antimicrobial peptides has been investigated with the intention of generating cyclic β sheets as promising antimicrobials with improved therapeutic potential. The linear peptides were cyclized head to tail either directly or after the addition of either a second turn motif or a disulfide bridge. The propensity of these peptides to adopt a cyclic β-sheet structure has been correlated to their antibacterial activity. All cyclic peptides showed enhanced activity, compared with their linear counterparts against methicillin-resistant Staphylococcus aureus. Scanning electron microscopy and transmission electron microscopy studies showed that this family kills bacteria through membrane lysis. The peptide that showed the best efficacy against all strains (exhibiting nanomolar activity), while retaining low haemolysis, bears two symmetrical, homochiral d-phe-2-Abz-d-ala turns and adopted a flexible structure. Its twin peptide that bears heterochiral turns (one with d-ala and one with L-Ala) showed reduced antibacterial activity and higher percentage of haemolysis. Circular dichroism and nuclear magnetic resonance spectroscopy indicate that heterochirality in the two turns leads to oligomerization of the peptide at higher concentrations, stabilizing the β-sheet secondary structure. More rigid secondary structure is associated with lower activity against bacteria and loss of selectivity.
Collapse
Affiliation(s)
- Kyriakos G Varnava
- School of Chemical Sciences, The University of Auckland, Auckland, 1142, New Zealand
| | - Patrick J B Edwards
- School of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand.,Maurice Wilkins Centre for Molecular BioDiscovery, Auckland, 1142, New Zealand
| | - Alan J Cameron
- School of Chemical Sciences, The University of Auckland, Auckland, 1142, New Zealand.,Maurice Wilkins Centre for Molecular BioDiscovery, Auckland, 1142, New Zealand
| | - Elena Harjes
- School of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand.,Maurice Wilkins Centre for Molecular BioDiscovery, Auckland, 1142, New Zealand
| | - Vijayalekshmi Sarojini
- School of Chemical Sciences, The University of Auckland, Auckland, 1142, New Zealand.,The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, 6140, New Zealand
| |
Collapse
|
3
|
Cameron AJ, Varnava KG, Edwards PJB, Harjes E, Sarojini V. Acyclic peptides incorporating the d-Phe-2-Abz turn motif: Investigations on antimicrobial activity and propensity to adopt β-hairpin conformations. J Pept Sci 2018; 24:e3094. [PMID: 29900628 DOI: 10.1002/psc.3094] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 05/08/2018] [Accepted: 05/16/2018] [Indexed: 02/01/2023]
Abstract
Three linear peptides incorporating d-Phe-2-Abz as the turn motif are reported. Peptide 1, a hydrophobic β-hairpin, served as a proof of principle for the design strategy with both NMR and CD spectra strongly suggesting a β-hairpin conformation. Peptides 2 and 3, designed as amphipathic antimicrobials, exhibited broad spectrum antimicrobial activity, with potency in the nanomolar range against Staphylococcus aureus. Both compounds possess a high degree of selectivity, proving non-haemolytic at concentrations 500 to 800 times higher than their respective minimal inhibitory concentrations (MICs) against S. aureus. Peptide 2 induced cell membrane and cell wall disintegration in both S. aureus and Pseudomonas aeruginosa as observed by transmission electron microscopy. Peptide 2 also demonstrated moderate antifungal activity against Candida albicans with an MIC of 50 μM. Synergism was observed with sub-MIC levels of amphotericin B (AmB), leading to nanomolar MICs against C. albicans for peptide 2. Based on circular dichroism spectra, both peptides 2 and 3 appear to exist as a mixture of conformers with the β-hairpin as a minor conformer in aqueous solution, and a slight increase in hairpin population in 50% trifluoroethanol, which was more pronounced for peptide 3. NMR spectra of peptide 2 in a 1:1 CD3 CN/H2 O mixture and 30 mM deuterated sodium dodecyl sulfate showed evidence of an extended backbone conformation of the β-strand residues. However, inter-strand rotating frame Overhauser effects (ROE) could not be detected and a loosely defined divergent hairpin structure resulted from ROE structure calculation in CD3 CN/H2 O. The loosely defined hairpin conformation is most likely a result of the electrostatic repulsions between cationic strand residues which also probably contribute towards maintaining low haemolytic activity.
Collapse
Affiliation(s)
- Alan J Cameron
- School of Chemical Sciences, The University of Auckland, Auckland, 1142, New Zealand
| | - Kyriakos G Varnava
- School of Chemical Sciences, The University of Auckland, Auckland, 1142, New Zealand
| | - Patrick J B Edwards
- Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand
| | - Elena Harjes
- Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand
| | | |
Collapse
|
4
|
Abstract
Amide rotation of peptidyl-prolyl fragments is an important factor in backbone structure organization of proteins. Computational studies have indicated that this rotation preferentially proceeds through a defined transition-state structure (syn/exo). Here, we complement the computational findings by determining the amide bond rotation barriers for derivatives of the two symmetric proline analogues, meso and racemic pyrrolidine-2,5-dicarboxylic acids. The rotations around these residues represent syn/exo-syn/exo and anti/endo-syn/exo hybrid transition states for the meso and racemic diastereomer, respectively. The rotation barriers are lower for the former rotation by about 9 kJ mol-1 (aqueous medium), suggesting a strong preference for the syn/exo (clockwise) rotation over the anti/endo (anticlockwise) rotation. The results show that both hybrid rotation processes are enthalpically driven but respond differently to solvent polarity changes due to the different transition state dipole-dipole interactions.
Collapse
Affiliation(s)
- Vladimir Kubyshkin
- Biocatalysis Group, Institute of Chemistry, Technical University of Berlin, Müller-Breslau-Str. 10, Berlin 10623, Germany.
| | - Nediljko Budisa
- Biocatalysis Group, Institute of Chemistry, Technical University of Berlin, Müller-Breslau-Str. 10, Berlin 10623, Germany.
| |
Collapse
|
5
|
Cameron AJ, Edwards PJB, Harjes E, Sarojini V. Tyrocidine A Analogues Bearing the Planar d-Phe-2-Abz Turn Motif: How Conformation Impacts Bioactivity. J Med Chem 2017; 60:9565-9574. [DOI: 10.1021/acs.jmedchem.7b00953] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Alan J. Cameron
- School
of Chemical Sciences, University of Auckland, Auckland 1142, New Zealand
| | - Patrick J. B. Edwards
- Institute
of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Elena Harjes
- Institute
of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
| | | |
Collapse
|
6
|
Cameron AJ, Squire CJ, Edwards PJB, Harjes E, Sarojini V. Crystal and NMR Structures of a Peptidomimetic β-Turn That Provides Facile Synthesis of 13-Membered Cyclic Tetrapeptides. Chem Asian J 2017; 12:3195-3202. [PMID: 29098772 DOI: 10.1002/asia.201701422] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 10/30/2017] [Indexed: 12/31/2022]
Abstract
Herein we report the unique conformations adopted by linear and cyclic tetrapeptides (CTPs) containing 2-aminobenzoic acid (2-Abz) in solution and as single crystals. The crystal structure of the linear tetrapeptide H2 N-d-Leu-d-Phe-2-Abz-d-Ala-COOH (1) reveals a novel planar peptidomimetic β-turn stabilized by three hydrogen bonds and is in agreement with its NMR structure in solution. While CTPs are often synthetically inaccessible or cyclize in poor yield, both 1 and its N-Me-d-Phe analogue (2) adopt pseudo-cyclic frameworks enabling near quantitative conversion to the corresponding CTPs 3 and 4. The crystal structure of the N-methylated peptide (4) is the first reported for a CTP containing 2-Abz and reveals a distinctly planar 13-membered ring, which is also evident in solution. The N-methylation of d-Phe results in a peptide bond inversion compared to the conformation of 3 in solution.
Collapse
Affiliation(s)
- Alan J Cameron
- School of Chemical Sciences, The University of Auckland, Auckland, 1142, New Zealand
| | - Christopher J Squire
- School of Biological Sciences, The University of Auckland, Auckland, 1142, New Zealand
| | - Patrick J B Edwards
- Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand
| | - Elena Harjes
- Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand
| | | |
Collapse
|