The peptide encoded by angiotensin II complementary RNA does not interfere with angiotensin II action

Clustered complementary amino acid pairing (CCAAP) for protein-protein interaction

OBJECTIVES

Designing a polypeptide sequence to interact with a preselected target polypeptide sequence of a protein has long been of interest, yet remains an elusive goal.

RESULTS

Here, we propose a novel concept named "Clustered Complementary Amino Acid Pairing (CCAAP)," which plays an essential role in protein-protein interaction (PPI). Complementary amino acid pairing (CAAP) is a pairing between two amino acids encoded by a codon and its reverse complementary codon. CAAP interactions largely agree with the physicochemical and stereochemical requirements for probable amino acid pairings. Interestingly, 82 PPI structure data revealed that clusters of CAAP interactions (CCAAP boxes) are predominantly found in all PPI sites. Analysis of all amino acid pairings in the CCAAP boxes unveiled amino acid-pairing preferences and patterns for PPI that allowed us to develop a new method for designing an oligopeptide sequence to bind to a chosen polypeptide sequence of any target protein.

CONCLUSIONS

Discoveries in the present study provide proof of the CCAAP principle.

Molecular recognition theory and sense-antisense interaction: therapeutic applications in autoimmunity

Perhaps behind only the understanding of the genetic code in importance is the comprehension of protein sequence and structure in its effect on modern scientific investigation. How proteins are structured and interact dictates a considerable amount of the body's processes in maintaining homeostasis. Unfortunately, in diseases of autoimmunity, these processes are directed against the body itself and most of the current clinical responses are severely lacking. This review addresses current therapeutics involved in the treatment of various autoimmune diseases and details potential future therapeutics designed with a more targeted approach. Detailed in this manuscript is the concept of utilizing peptides possessing an inverse hydropathy to the immunogenic region of proteins to generate anti-idiotypic (anti-Id) and anti-clonotypic T cell receptor (TCR) antibodies (Abs). Theoretically, the anti-Id Abs cross react with Id Abs and negate the powerful machinery of the adaptive immune response with little to no side effects. A series of studies by a number of groups have shown this to be an exciting and intriguing concept that will likely play a role in the future treatment of autoimmune diseases.

Molecular recognition theory and sense-antisense interaction: therapeutic applications in autoimmunity

Perhaps behind only the understanding of the genetic code in importance is the comprehension of protein sequence and structure in its effect on modern scientific investigation. How proteins are structured and interact dictates a considerable amount of the body's processes in maintaining homeostasis. Unfortunately, in diseases of autoimmunity, these processes are directed against the body itself and most of the current clinical responses are severely lacking. This review addresses current therapeutics involved in the treatment of various autoimmune diseases and details potential future therapeutics designed with a more targeted approach. Detailed in this manuscript is the concept of utilizing peptides possessing an inverse hydropathy to the immunogenic region of proteins to generate anti-idiotypic (anti-Id) and anti-clonotypic T cell receptor (TCR) antibodies (Abs). Theoretically, the anti-Id Abs cross react with Id Abs and negate the powerful machinery of the adaptive immune response with little to no side effects. A series of studies by a number of groups have shown this to be an exciting and intriguing concept that will likely play a role in the future treatment of autoimmune diseases.

Inhibition of HIV-1 infection by an intramolecular antisense peptide to T20 in gp160

Antisense amino acids are amino acids which can be translated from the corresponding anti-codons of a sense amino acid. Antisense peptides encoded by the noncoding DNA strand have a tendency to interact with each other. We have demonstrated that antisense peptide sequences are present intramolecularly, and these may contribute to the folding and maintenance of the tertiary structure of a protein. T20 is a synthetic peptide with an amino acid sequence in the gp41 of HIV-1 and has been demonstrated to be a potent inhibitor of HIV-1 infection. We searched for intramolecular peptide sequences which are antisense to portions of T20. A synthetic peptide (TA-1L) consisting of amino acids 84 to 97 of gp160, which contains an antisense peptide sequence (TA-1) to T20, was shown to inhibit HIV-1(IIIB) infection of MT-4 cells. Interaction of these antisense peptides could be involved in sustaining HIV-1 infectivity. The TA-1L site, which exists in the C1 domain of gp160, is highly homologous among strains of HIV-1, especially at TA-1 and in the amino acids flanking the C terminus. Although the TA-1 sites of 18 out of 30 HIV-1 strains were antisense to the T20 region, those of the remaining 12 strains, including HIV-1(MN), were not. However, TA-1L inhibited infection by HIV-1(MN), which has no antisense peptide in T20 corresponding to TA-1, although the inhibitory effect was weaker. TA-1L may thus also interfere with the gp160 interaction with CD4, which has an antisense sequence to TA-1.

Augmentation of aortic ring contractions by angiotensin II antisense peptide

Previous biochemical experiments have revealed two antisense peptide antagonists to human angiotensin II (Ang II), one encoded in the cDNA in the antiparallel reading, the other in the parallel reading. Neither peptide's ability to produce physiological antagonism has been demonstrated previously. Both peptides were tested for their ability to antagonize Ang II-induced contractions on rabbit aorta smooth muscle. Neither peptide had any direct contractile activity. The antiparallel Ang II peptide had physiological antagonism to Ang II contractions at a lower sensitivity than reported in biochemical studies, and its antagonist activity was partially blocked by Ang II antiserum, suggesting that it is not an antipeptide but an Ang II homologue. The parallel Ang II antipeptide also required high concentrations for physiological inhibition. Its contractile inhibition was not affected by Ang II antiserum and diminished the Ang II contraction at high micromolar concentrations, findings consistent with physicochemical data showing that it is an Ang II complement. The concentration of either peptide required to produce an antagonistic physiological effect was too high to predict any pharmacological usefulness. The parallel antipeptide, however, significantly increased the force of muscle contractions at high nanomolar concentrations, thus displaying a unique dual augmentation/antagonist activity. This antipeptide seems to have highly sequence-specific activity because other similar parallel antipeptides had no activity. The parallel antipeptide augmentation mimics the shift in the Ang II dose-response curve produced in hypertension studies of the slow pressor effect of Ang II and may be useful in deducing the currently unknown cause of the slow pressor effect. It may also have some uses in migraine studies.

The antisense homology box: a new motif within proteins that encodes biologically active peptides

Amphiphilic peptides approximately fifteen amino acids in length and their corresponding antisense peptides exist within protein molecules. These regions (termed antisense homology boxes) are separated by approximately fifty amino acids. Because many sense-antisense peptide pairs have been reported to recognize and bind to each other, antisense homology boxes may be involved in folding, chaperoning and oligomer formation of proteins. The antisense homology box-derived peptide CALSVDRYRAVASW, a fragment of human endothelin A receptor, proved to be a specific inhibitor of endothelin peptide (ET-1) in a smooth muscle relaxation assay. The peptide was able to block endotoxin-induced shock in rats as well. Our finding of endothelin receptor inhibitor among antisense homology box-derived peptides indicates that searching proteins for this new motif may be useful in finding biologically active peptides.

Studies on T-cell receptors involved in experimental autoimmune encephalomyelitis using the complementary peptide recognition approach

Based upon Blalock's complementary recognition approach, a complementary or antisense peptide (CP) was designed to the experimental autoimmune encephalomyelitis (EAE) epitope peptide, rat myelin basic protein (MBP) peptide 72-82. This peptide (EAE CP) was shown to have some sequence similarities to T-cell receptors (TCR) and MHC II molecules in a sequence homology search. Solid-phase binding assays demonstrated specific and high affinity binding (3 and 4 microM) between the EAE CP and the rat and guinea pig EAE epitope peptides (Rt72-82 and Gp69-82), respectively. This EAE CP was also found to be immunogenic in rats in an ear swelling test for delayed type hypersensitivity (DTH) reactions and an ELISA for antibody responses. However, a rabbit antibody generated to EAE CP was shown to be unable to stain the V beta 8+ EAE susceptible T-cells in immunofluorescence analyses. This EAE CP was also used in attempts to down-regulate EAE and the results showed that prior immunization with EAE CP in complete Freund's adjuvant could not prevent the Lewis rats from developing EAE. Although the data on sense-antisense peptide interaction were positive and the EAE CP was immunogenic, the inability of EAE CP to regulate EAE indicates that the CP approach may not be generally applicable.

Nucleic acid sequences coding for internal antisense peptides: are there implications for protein folding and evolution?

We have asked whether coding segments of nucleic acids generate amino acid sequences which have an antisense relationship to other amino acid sequences in the same chain (i.e. 'Internal Antisense'), and if so, could the internal antisense content be related to the structure of the encoded protein? Computer searches were conducted with the coding sequences for 132 proteins. The result for each search of a specific sequence was compared to the mean result obtained from 1000 randomly assembled nucleic acid chains whose length and base composition were identical to that of the native sequences. The study was conducted in all three reading frames. The normal reading frame (frame one) was found to be contain lower amounts of internal antisense than the randomly assembled chains, whereas the frame two results were much higher. The internal antisense content in frame three was not significantly different from that in the random chains. The amount of internal antisense in frames two and three was correlated with the GC content at the center position of the codons in that frame, but this correlation was absent in frame one. No correlation with chain length was found. Qualitatively similar results were obtained when the random model was limited to retain the same purine/pyrimidine ratio as the native chains at each position in the codons, but in this case the internal antisense in frame three was also significantly greater than the computer-generated sequences. The results suggest that the internal antisense content in the correct reading frame has a qualitatively different origin from that in the other two frames. The high amount in frames two and three is apparently an artifact resulting from the asymmetric distribution of G and C in the codons, while the low amount in frame one may suggest evolutionary selection against internal antisense. Thus, the results do not support a relationship between internal antisense and protein structure.

Lack of interaction of vasopressin with its antisense peptides: a functional and immunological study

The peptide encoded in the 5' to 3' direction by rat vasopressin complementary RNA, rat PVA (H-Ser-Ser-Trp-Ala-Val-Leu-Glu-Val-Ala- OH) and the corresponding bovine PVA (H-Ala-Pro-Trp-Ala-Val-Leu-Glu-Val-Ala-OH) were investigated with respect to their interaction with [8-arginine] vasopressin (AVP) and V2 vasopressin receptor binding and function. Rat or bovine PVA did neither affect the binding of the hormone to the V2 receptor of bovine kidney membranes and LLC-PK1 pig kidney cells nor influence the AVP-induced cAMP-production in LLC-PK1 cells. Rat PVA was further investigated by the use of vasopressin-specific polyclonal and monoclonal antibodies with different affinity and epitope specificity. Consistent with receptor binding studies no inhibition of [3H]AVP-binding in fluid- or solid-phase antibody binding tests after preincubation with PVA was found. Direct interaction of rat PVA and [3H]AVP measured on solid surface was not observed in contrast to specific binding of the hormone with NP II and antibodies. In our study no evidence for an interaction of AVP and its antisense peptides was found.

Studies on the peptides encoded by rat and human angiotensin II complementary RNA

Some evidence suggests that RNA complementary to the messenger RNA encoding a peptide hormone encodes a complementary peptide that binds the original peptide hormone. The objective of this investigation was to assess in vivo the ability of complementary angiotensin II (II Ang) peptides to block the biological effects of angiotensin II (Ang II). Increasing concentrations of rat or human II Ang were preincubated with Ang II for 2 hours, and this solution was then infused intra-arterially into the superior mesenteric artery. Human, but not rat, II Ang dose-dependently inhibited Ang II-induced mesenteric vasoconstriction. The in vivo inhibitory potencies of human II Ang and [Sar1,Ile8]Ang II, with respect to inhibition of the pressor response to Ang II, were compared by infusing intravenously increasing doses of each blocker and determining their effects on a fixed intravenous dose of Ang II. Although human II Ang could abolish the pressor response to Ang II, [Sar1,Ile8]Ang II was approximately 100 times more potent in this regard. A fixed dose of human II Ang (150 micrograms/min i.v.) inhibited the effects of increasing doses of Ang II on mesenteric vascular resistance, arterial blood pressure, and aldosterone secretion. The 1H nuclear magnetic resonance spectra of human II Ang and Ang II were determined both separately and when combined in the same cuvette. The spectrum obtained by overlaying the separate spectra for these two peptides was the same as the spectrum obtained from the mixture of these two peptides in the same cuvette.(ABSTRACT TRUNCATED AT 250 WORDS)

Making sense from antisense: a review of experimental data and developing ideas on sense--antisense peptide recognition

Peptides encoded in the antisense strand of DNA have been predicted and found experimentally to bind to sense peptides and proteins with significant selectivity and affinity. Such sense--antisense peptide recognition has been observed in many systems, most often by detecting binding between immobilized and soluble interaction partners. Data obtained so far on sequence and solvent dependence of interaction support a hydrophobic-hydrophilic (amphipathic) model of peptide recognition. Nonetheless, the mechanistic understanding of this type of molecular recognition remains incomplete. Improving this understanding likely will require expanding the types of characteristics measured for sense--antisense peptide complexes and hence the types of analytical methods applied to such interactions. Understanding the mechanism of sense--antisense peptide recognition also may provide insights into mechanisms of native (sense) peptide and protein interactions and protein folding. Such insight may be helpful to learn how to design macromolecular recognition agents in technology for separation, diagnostics and therapeutics.

Interactions and uses of antisense peptides in affinity technology

Antisense peptides, amino acid sequences encoded in the antisense strand of DNA, can interact with significant affinity and selectivity with their corresponding sensepeptides. Experimentally, sense-antisense peptide recognition has been observed repeatedly. However, skepticism about the biological relevance of this phenomenon has persisted. This is due in part to the unexpected and somewhat couterintutive nature of the interaction as well as to its non-universality as an empirical observation. Nonetheless, antisense peptides in several cases investigated so far have been used as immobilized ligands for the successful affinity chromatographic separation of native (sense) peptides and proteins. For example, immobilized antisense peptides corresponding to Arg8-vasopressin (AVP) have been used to separate vasopressin from oxytocin chromatographically as well as to affinity capture AVP-receptor complex. These results, together with improved understanding of the general features of amino acid sequence which drive antisense-sense peptide interactions as well as new ideas for making antisense peptides chimeras, are beginning to suggest improved ways to make antisense-related peptides as affinity agents for separation as well as for other biotechnology applications.

Critical evaluation of a theory of molecular recognition using human insulin-like-growth-factor-I fragment 21-40 and its complementary peptide

Using solid-phase methods we have synthesized human insulin-like-growth-factor-I (IGF-I) fragment 21-40 (IGF-I 21-40) and the peptide derived from the 5'----3' translation of the complementary nucleic acid of this peptide, 'I-FGI 20-40' (the complementary peptide). According to a recently proposed theory of molecular recognition, these two peptides should bind specifically to each other. We have tested this theory by using both solid- and solution-phase direct-binding assays for this complementary-peptide pair. We have also investigated the ability of I-FGI 20-40 to interfere with native IGF-I binding during radioimmunoassay (r.i.a.), radio-receptor (r.r.a.) assay and ligand-blot analysis of IGF-binding proteins. We have obtained no evidence of any interaction between IGF-I 21-40 and I-FGI 20-40 in either solid- or solution-phase assays. In addition, I-FGI 20-40 does not interfere in the assays used to detect IGF-I binding antibodies (r.i.a.), receptors (r.r.a.) or binding proteins (ligand blots). Our data therefore question the universality of this particular theory of molecular recognition.

Antagonist effect of a receptor-mimicking peptide encoded by human angiotensin II complementary RNA

This article reports on the binding and the angiotensin II (Ang II) antagonistic properties of a peptide, referred to as hIIA, encoded by an RNA strand complementary to the human Ang II messenger RNA. Although Ang II and hIIA (H2N-Glu-Gly-Val-Tyr-Val-His-Pro-Val-COOH) share four amino acids, the iodinated and tritiated forms of hIIA were unreactive with seven monoclonal antibodies defining four distinct epitopes on the Ang II molecule and failed to bind to Ang II hepatic and mesangial receptors. However, hIIA did inhibit binding of 125I-Ang II to rat hepatocyte membranes (IC50, 2 x 10(-7) M) and to the various monoclonal antibodies. The lowest IC50 (5 x 10(-7) M) was measured with the monoclonal antibody specific for the Ang II sequence generally considered as implicated in receptor recognition. As predicted from the binding studies, hIIA was further shown to antagonize some biological properties of Ang II. On mesangial cells, hIIA alone had no effect on intracellular calcium concentration ([Ca2+]i) and prostaglandin E2 synthesis but did abolish the transient increase in [Ca2+]i in response to 100 nM Ang II and did induce a specific dose-dependent inhibition of the Ang II-stimulated prostaglandin E2 release. Furthermore, intravenous infusion of hIIA (200 micrograms.kg-1.min-1) inhibited by 66 +/- 3% the rat hypertensive response to 100 ng.kg-1 Ang II but had no effect on the pressor activity of agents such as alpha 1-adrenergic and HT2 serotonin agonists. Our data suggest that the "complementary" peptide hIIA interacts directly with Ang II by mimicking the Ang II complementary site on the receptor and can inhibit the physiological effects of Ang II. This type of Ang II complementary peptide may serve as a model for a new class of antihypertensive drugs.

Antisense peptides: tools for receptor isolation? Lack of antisense MSH and ACTH to interact with their sense peptides and to induce receptor-specific antibodies

The use of antisense peptides for receptor isolation as proposed by Blalock and his colleagues (e.g. TIBTECH 8, 140-144, 1990) was tested for human ACTH as well as alpha- and beta-MSH. We synthesized the corresponding antisense peptides HTCAh, HSM-alpha and HSM-beta and analyzed them for specific interaction with the sense peptides using several types of binding assay and bioassay. Similarly HTCAh antibodies were tested for binding to ACTH receptors and ACTH antibodies. All these experiments were negative, i.e. there was no specific interaction between sense and antisense peptides nor between the corresponding antibodies. Receptor binding of the sense peptides was not affected by the antisense peptides or HTCAh antibodies. Unexpectedly, HTCAh but not HSM-alpha or HSM-beta was a weak MSH agonist acting through a site independent of the MSH receptor. A detailed analysis of the concept of antisense peptides revealed that the theoretical background of the hypothesis of the 'molecular recognition theory' is rather weak, explaining the failure of various attempts to obtain specific receptor antibodies.

Binding and pharmacologic properties of peptides derived from human and rat angiotensin II (AII) mRNA

We investigated the binding and pharmacologic properties of peptides encoded by complementary mRNA derived from the human and rat angiotensinogen gene (human and rat IIA, respectively). Human IIA (identical with AII in 4 amino acids) inhibited binding of [125I]AII to rat adrenal glomerulosa particles (Ki = 0.62 +/- 0.09 microM) and competitively blocked, with similar potency, the ability of three AII receptor agonists to contract rabbit aorta. Rat IIA affected neither [125I]AII binding to glomerulosa particles nor the contractile response of AII. We conclude that rat IIA does not interact with AII or its receptors and that human IIA acts as a competitive inhibitor of AII at the receptor level.

NMR study of the possible interaction in solution of angiotensin II with a peptide encoded by angiotensin II complementary RNA

The potential binding of angiotensin II (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe) (AII) to a peptide encoded by its complementary RNA (Lys-Gly-Val-Asp-Val-Tyr-Ala-Val) (IIA) has been studied by monitoring the 1H NMR spectrum of IIA in aqueous phosphate or Tris.HCl buffer (2H2O) as it is titrated with AII. For molar ratios of AII/IIA ranging from 0.2 to 1.8, the NMR spectra are unchanged as compared to the spectra of the isolated peptides. Based on these findings, the Kd for the putative biomolecular complex of the two peptides under these conditions is calculated to be greater than 10(-4) M. This result does not support the suggestion of Elton et al. [Elton, T. S., Dion, L.D., Bost, K. L., Oparil, S. & Blalock, J. E. (1988) Proc. Natl. Acad. Sci. USA 85, 2518-2522] that AII and IIA engage in high-affinity binding (Kd approximately 5 x 10(-8) M) with each other.