The toad, ugly and venomous, wears yet a precious jewel in his skin

Lazarus, Lawrence H.; Attila, Martti

doi:10.1016/0301-0082(93)90027-p

Cited by 202 publications

(141 citation statements)

References 223 publications

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“…Amphibian skin is one of the sources of these peptides [2]. One well-studied example is the magainin family of peptides isolated from the south African clawed frog Xenopus laevis [3].…”

Section: Introductionmentioning

confidence: 99%

The orientation of the antibiotic peptide maculatin 1.1 in DMPG and DMPC lipid bilayers. Support for a pore‐forming mechanism

et al. 2002

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Maculatin 1.1 is an antimicrobial peptide isolated from the Australian tree frog Litoria genimaculata that adopts an amphipathic, K K-helical structure in solution. Its orientation and conformation when incorporated to pre-formed DMPG (1,2-dimyristoyl-sn-glycero-3-phosphoglycerol) and DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) vesicles was determined using polarised Fourier transform infrared^attenuated total reflection infrared and deuterium exchange experiments. For DMPG membranes, our results show insertion of V V70% of the maculatin 1.1 molecules, with an angle of insertion of approximately 35³ to the membrane normal and with a predominant K K-helical structure. These results suggest that maculatin 1.1 acts through a pore-forming mechanism to lyse bacterial membranes. A similar degree of insertion in DMPG (65%) and K K-helical structure was observed for a biologically inactive, less amphipathic maculatin 1.1 analogue, P15A, although the helix tilt was found to be greater (46³) than for maculatin 1.1. Similar experiments performed using DMPC liposomes showed poor insertion, less than 5%, for both maculatin 1.1 and its analogue. In addition, the shape of the amide I band in these samples is consistent with K K-helix, L L-structure and disordered structures being present in similar proportion. These results clearly show that maculatin 1.1 inserts preferentially in negatively charged membranes (DMPG) which mimic the negatively charged membrane of Gram-positive bacteria. We attribute the high percentage of insertion of the biologically inactive analogue in DMPG to the fact that its concentration on the membrane surface in our experiments is likely to be much higher than that found in physiological conditions. ß 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

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“…Amphibian skin is one of the sources of these peptides [2]. One well-studied example is the magainin family of peptides isolated from the south African clawed frog Xenopus laevis [3].…”

Section: Introductionmentioning

confidence: 99%

The orientation of the antibiotic peptide maculatin 1.1 in DMPG and DMPC lipid bilayers. Support for a pore‐forming mechanism

et al. 2002

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“…Currently, in excess of 100 peptides have been structurally characterized, and these have been classified into several families based upon primary structural similarities (2). Many of these peptides have primary structures that are either identical to their endogenous mammalian counterparts (e.g.…”

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confidence: 99%

Isolation, Structural Characterization, and Bioactivity of a Novel Neuromedin U Analog from the Defensive Skin Secretion of the Australasian Tree Frog, Litoria caerulea

Salmon¹,

Johnsen²,

Bienert³

et al. 2000

Journal of Biological Chemistry

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We report the isolation of a novel bioactive peptide, neuromedin U-23 (NmU-23), from the defensive skin secretion of the Australasian tree frog, Litoria caerulea. The primary structure of the peptide was established by a combination of microsequencing, mass spectroscopy and site-directed antiserum immunoreactivity as SDEEVQVPGGVISNGYFLFRPRN-amide (M r 2580.6). A synthetic replicate of frog NmU-23 displaced monoradioiodinated rat NmU-23 from uterine membranes in a dose-dependent fashion indistinguishable from nonisotopically labeled rat NmU-23. In a rat uterine smooth muscle strip preparation, synthetic frog NmU-23 produced dose-dependent contractions identical to porcine NmU-25. However, in a preparation of human urinary bladder muscle strip, the synthetic frog peptide was more potent than porcine NmU-25 in eliciting contraction and produced desensitization of the preparation to the latter peptide. This report demonstrates that the defensive skin secretion of a frog contains a novel peptide exhibiting a high degree of primary structural similarity to the endogenous vertebrate peptide, NmU, and that this frog skin analog displays biological activity in mammalian tissues.

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“…Synthetic replicates of each novel bradykinin were found to be active on mammalian arterial and small intestinal smooth muscle preparations. The structural diversity of bradykinins in amphibian defensive skin secretions may be related to defence against specific predators.Keywords: amphibian; bradykinin; skin; precursor; cloning.The skins of anuran amphibians, in addition to mucous glands, contain highly specialized poison glands, which, in reaction to stress or attack, exude a complex noxious cocktail of biologically active molecules [1]. These secretions often contain a plethora of peptides among which bradykinin or structural variants have been identified [2][3][4][5].…”

mentioning

confidence: 99%

Novel bradykinins and their precursor cDNAs from European yellow‐bellied toad (Bombina variegata) skin

Chen

Orr

Bjourson

et al. 2002

European Journal of Biochemistry

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Two novel bradykinin-related peptides (Ala3,Thr6)-bradykinin and (Val1,Thr3,Thr6)-bradykinin, were identified by a systematic sequencing study of peptides in the defensive skin secretion of the yellow-bellied toad, Bombina variegata. These peptides are the first amphibian skin bradykinins to exhibit amino acid substitutions at the Pro3 position of the bradykinin nonapeptide. Previously reported bradykinins from other Bombina species were not detected. Respective precursor cDNAs, designated BVK-1 and BVK-2, respectively, were cloned from a skin library by 3¢-and 5¢-RACE reactions. BVK-1 contained an open-reading frame of 97 amino acids encoding a single copy of (Ala3,Thr6)-bradykinin and similarly, the open-reading frame of BVK-2 consisted of 96 amino acids encoding a single copy of (Val1,Thr3,Thr6)-bradykinin. Synthetic replicates of each novel bradykinin were found to be active on mammalian arterial and small intestinal smooth muscle preparations. The structural diversity of bradykinins in amphibian defensive skin secretions may be related to defence against specific predators.Keywords: amphibian; bradykinin; skin; precursor; cloning.The skins of anuran amphibians, in addition to mucous glands, contain highly specialized poison glands, which, in reaction to stress or attack, exude a complex noxious cocktail of biologically active molecules [1]. These secretions often contain a plethora of peptides among which bradykinin or structural variants have been identified [2][3][4][5].The kallikrein-kininogen system appears to be a common target for certain venom components of many invertebrates and vertebrates. Among snakes, venoms from members of the Crotalinae (pit vipers) contain low molecular mass peptides that inhibit angiotensin-converting enzyme -a major bradykinin inactivating protease -thus potentiating the activity of endogenous bradykinin [6]. These bradykinin-potentiating peptides were the leads in developing angiotensin-converting enzyme inhibitor drugs that are frontline pharmaceuticals in the treatment of hypertension.Peptides with angiotensin-converting enzyme inhibitory activity have also been isolated from scorpion venom [7,8]. Wasp venoms contain bradykinin-related peptides that are responsible for the reddening, oedema and intense pain associated with envenomation by these insects [9,10]. These molecular strategies appear to be related to either potentiation of the effects of endogenous bradykinin by inhibition of catabolic proteases (snakes and scorpions) or by local delivery of supraphysiological quantities of bradykinins (wasps and amphibians).Although canonical bradykinin (RPPGFSPFR) has been isolated from the European common frog (Rana temporaria), with a range of minor N-and C-terminally extended forms [11,12], other species of ranid frog have been found to contain structural variants. These include (Thr6)-bradykinin and (Thr6)-bradykinyl-IAPEIV in R. rugosa and (Val1, Thr6)-bradykinin and (Val1,Thr6)-bradykinyl-VAPAS in R. nigromaculata [13,14]. Additional structural variants such as phylloki...

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The toad, ugly and venomous, wears yet a precious jewel in his skin

Cited by 202 publications

References 223 publications

The orientation of the antibiotic peptide maculatin 1.1 in DMPG and DMPC lipid bilayers. Support for a pore‐forming mechanism

The orientation of the antibiotic peptide maculatin 1.1 in DMPG and DMPC lipid bilayers. Support for a pore‐forming mechanism

Isolation, Structural Characterization, and Bioactivity of a Novel Neuromedin U Analog from the Defensive Skin Secretion of the Australasian Tree Frog, Litoria caerulea

Novel bradykinins and their precursor cDNAs from European yellow‐bellied toad (Bombina variegata) skin

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