Differential activities of decapeptide agonists of human C5a: the conformational effects of backbone N-methylation

Vogen, Shawn M.; Paczkowski, Natalii J.; Kirnarsky, Leonid; Short, Anna; Whitmore, Jacqueline B; Sherman, Simon; Taylor, Stephen M.; Sanderson, Sam D.

doi:10.1016/s1567-5769(01)00141-2

Cited by 32 publications

(59 citation statements)

References 17 publications

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“…This analogue has a helix-bend-helix structure in aqueous media at near-physiological pH and ionic strength (14), similar to that found in previous studies of PTH-(1-34) (13). A C-terminal amphiphilic ␣-helix, extending from Ser 17 to Gln 29 , is the major structure within this receptorbinding region, and this structure is thought to bind via its hydrophobic face to the receptor (21)(22)(23). Thus, binding and AC-stimulating activities are very sensitive to replacement of residues on the nonpolar face of this helix, including Leu 24 , Leu 28 , and to a lesser extent Val 31 , whereas residues on the polar face are less sensitive to substitution (22,24).…”

supporting

confidence: 81%

“…Circular Dichroism-To obtain the spectrum of the Ser 17 -Gln 29 helix within hPTH-(1-31)NH 2 and other analogues described here, we subtracted the spectrum for hPTH-(1-17)NH 2 . The only structure, based on NMR data, within residues 1-17 of hPTH-(1-31)NH 2 is a short ␣-helix between residues 3-9 (14), and this short helix contributes little to the ␣-helix of hPTH-(1-31)NH 2 .…”

Section: Resultsmentioning

confidence: 99%

“…These methylations have been used successfully to modulate binding specificity of an agonist for the C5A anaphylatoxin receptors (29), and to create subtype-specific somatostatin receptor agonists and antagonists (30,31). Methylation of a backbone NH not only prevents formation of a H-bond at that point, but it also has an effect on secondary structures, such as ␣-helices or ␤-turns, that may have existed in the region of the modification.…”

mentioning

confidence: 99%

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Backbone-methylated Analogues of the Principle Receptor Binding Region of Human Parathyroid Hormone

Barbier

Gardella

Dean

et al. 2005

Journal of Biological Chemistry

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We have used backbone N-methylations of parathyroid hormone (PTH) to study the role of these NH groups in the C-terminal amphiphilic ␣-helix of PTH (1-31) in binding to and activating the PTH receptor (P1R). The circular dichroism (CD) spectra indicated the structure of the C-terminal ␣-helix was locally disrupted around the methylation site. The CD spectra differences were explained by assuming a helix disruption for four residues on each side of the site of methylation and taking into account the known dependence of CD on the length of an ␣-helix. Binding and adenylyl cyclase-stimulating data showed that outside of the ␣-helix, methylation of residues Asp 30 and Val 31 had little effect on structure or activities. Within the ␣-helix, disruption of the structure was associated with increased loss of activity, but for specific residues Val 21 , Leu 24 , Arg 25 , and Leu 28 there was a dramatic loss of activities, thus suggesting a more direct role of these NH groups in correct P1R binding and activation. Activity analyses with P1R-delNT, a mutant with its long N-terminal region deleted, gave a different pattern of effects and implicated Ser 17 , Trp 23 , and Lys 26 as important for its PTH activation. These two groups of residues are located on opposite sides of the helix. These results are compatible with the C-terminal helix binding to both the N-terminal segment and also to the looped-out extracellular region. These data thus provide direct evidence for important roles of the C-terminal domain of PTH in determining high affinity binding and activation of the P1R receptor.

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supporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Backbone-methylated Analogues of the Principle Receptor Binding Region of Human Parathyroid Hormone

Barbier

Gardella

Dean

et al. 2005

Journal of Biological Chemistry

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“…The most common modification has been N-methylation of the amide nitrogen of peptide ligands, which changes the conformation of the peptide, thus affecting its biological activity. This approach has been used to design selective agonists and/or antagonists and also to impart resistance to hydrolysis by the proteolytic enzymes [6]. Another strategy has been the preparation of N-hydroxyamides, which are good metal chelators and can impart conformational rigidity to the peptides [7].…”

Section: Introductionmentioning

confidence: 99%

Geometry, transition states, and vibrational spectra of boron isostere of N‐methylacetamide by ab initio calculations

Malde

Khedkar

Coutinho

et al. 2005

Int J of Quantum Chemistry

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ABSTRACT:The basic unit of the peptide, the COONH bond, is responsible for imparting specific secondary structural features to peptides. Many modifications, such as isosteric/bioisosteric replacement of this basic unit, have been made to alter the properties of peptides. Isosteric replacement of the nitrogen atom by boron (boron peptides) is another plausible way of changing peptide characteristics. Like Nmethylacetamide (NMA), acetylmethylborane, or BMA, is a good model for studying boron peptides. The potential energy surface (PES) of BMA has been studied by Hartree-Fock (HF), density functional theory (DFT), and post-HF methods. The PES of BMA is an inverted form of the NMA hypersurface. Two minima and two saddle points of index 1 have been identified on this PES and fully optimized at the HF, Becke's three-parameter exchange functional and the gradient-corrected functional of Lee, Yang, and Paar, second-order Møller-Plesset (full), and quadratic configuration interaction method with single and double substitutions followed by a perturbative treatment of triple substitutions (QCISD) levels of theory. The minima correspond to structures with "omega" values close to 90°and 270°, and the transition states have omega values around 0°and 180°. The energy barrier for rotation around the "omega bond" is found to be 4.3 kcal/mol at the QCISD/6-31G* level, which is much lower than the 16 -23 kcal/mol barrier in NMA. The unique shape of the PES of BMA and the low barrier to rotation can be well explained by second-order orbital interaction studies. Normal-mode analysis reveals a significant shift in the BOH stretching frequency of BMA from that in alkyl boranes and borane-phosphine complexes. The replacement of nitrogen by boron bestows on such peptides greater proteolytic stability, more flexibility around the omega angle, and a unique preference for positive angles, all of which are absent in peptides of natural origin.

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“…Accordingly, we have engineered a conformationally biased, response-selective analogue of the biologically active C-terminal region of the human complement component C5a [65][66][67][68][69][70][71][72][73][74] (6). This analogue, termed EP67, has the sequence Tyr-Ser-Phe-Lys-AspMet-Pro-(N-methylLeu)-D-Ala-Arg, or YSFKDMP(MeL)aR, and was designed to bind C5a receptors (CD88) on antigen-presenting cells (APCs) such as macrophages but to limit inflammatory properties by not engaging C5aRs on polymorphonuclear cells (PMNs) (6,7). EP67 has shown adjuvant potential in vaccine designs against ovalbumin (6) and Coccidioides (8) by enhancing activation of a T H 1 response via engagement of C5aR-bearing APCs.…”

Section: S Treptococcus Agalactiae (Group B Streptococcus [Gbs]mentioning

confidence: 99%

A Novel C5a-Derived Immunobiotic Peptide Reduces Streptococcus agalactiae Colonization through Targeted Bacterial Killing

Cavaco

Patras

Zlamal

et al. 2013

Antimicrob Agents Chemother

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dStreptococcus agalactiae (group B Streptococcus [GBS]) is a Gram-positive bacterium that colonizes the cervicovaginal tract in approximately 25% of healthy women. Although colonization is asymptomatic, GBS can be vertically transmitted to newborns peripartum, causing severe disease such as pneumonia and meningitis. Current prophylaxis, consisting of late gestation screening and intrapartum antibiotics, has failed to completely prevent transmission, and GBS remains a leading cause of neonatal sepsis and meningitis in the United States. Lack of an effective vaccine and emerging antibiotic resistance necessitate exploring novel therapeutic strategies. We have employed a host-directed immunomodulatory therapy using a novel peptide, known as EP67, derived from the C-terminal region of human complement component C5a. Previously, we have demonstrated in vivo that EP67 engagement of the C5a receptor (CD88) effectively limits staphylococcal infection by promoting cytokine release and neutrophil infiltration. Here, using our established mouse model of GBS vaginal colonization, we observed that EP67 treatment results in rapid clearance of GBS from the murine vagina. However, this was not dependent on functional neutrophil recruitment or CD88 signaling, as EP67 treatment reduced the vaginal bacterial load in mice lacking CD88 or the major neutrophil receptor CXCr2. Interestingly, we found that EP67 inhibits GBS growth in vitro and in vivo and that antibacterial activity was specific to Streptococcus species. Our work establishes that EP67-mediated clearance of GBS is likely due to direct bacterial killing rather than to enhanced immune stimulation. We conclude that EP67 may have potential as a therapeutic to control GBS vaginal colonization.

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Differential activities of decapeptide agonists of human C5a: the conformational effects of backbone N-methylation

Cited by 32 publications

References 17 publications

Backbone-methylated Analogues of the Principle Receptor Binding Region of Human Parathyroid Hormone

Backbone-methylated Analogues of the Principle Receptor Binding Region of Human Parathyroid Hormone

Geometry, transition states, and vibrational spectra of boron isostere of N‐methylacetamide by ab initio calculations

A Novel C5a-Derived Immunobiotic Peptide Reduces Streptococcus agalactiae Colonization through Targeted Bacterial Killing

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