Phospholipase A2 in porifera

Molecular Cloning and Functional Analysis of Secretory Phospholipase A2 from Apostichopus japonicus

Secretory phospholipase A2 (sPLA2) plays important roles in phospholipid metabolism, skin barrier maintenance, immune response and other processes in organisms. sPLA2 of sea cucumber A. japonicus (AjPLA2) has not yet been reported. This study successfully amplified the AjPLA2 sequence. The total cDNA of AjPLA2 is 931 bp, including a 480 bp ORF that encodes 159 amino acids. The AjPLA2 protein includes a 16-aa signal peptide, a 5-aa precursor peptide and a 138-aa mature peptide. Homologous alignment showed that AjPLA2 and the sPLA2s from starfish have the typical domains of the Group IB sPLA2. And additional amino acid sequences were found around the β-Wing, which is different from the Group IB sPLA2. These results showed that AjPLA2 and sPLA2s from starfish all belong to a new group in the Group I sPLA2 family. AjPLA2 is widely distributed in sea cucumber tissues. The functional analysis also showed that AjPLA2 was upregulated in the intestine by feeding. When the body wall was damaged, it was significantly upregulated around the wound. And the expression levels of AjPLA2 were significantly increased in V. splendens-infected sea cucumbers. The results indicated that AjPLA2 plays roles in the sea cucumber immunologic process. Combined with the upregulation of unsaturated fatty acids (PUFAs) content in A. japonicus, it demonstrated that AjPLA2 could participate in the immune of A. japonicus by hydrolyzing phospholipid and releasing PUFAs. This study had a solid foundation for the further research of AjPLA2 gene function in vivo, development and application of AjPLA2 protein.

Conodipine-P1-3, the First Phospholipases A2 Characterized from Injected Cone Snail Venom

The phospholipase A₂ (PLA₂s) superfamily are ubiquitous small enzymes that catalyze the hydrolysis of phospholipids at the sn-2 ester bond. PLA₂s in the venom of cone snails (conodipines, Cdpi) are composed of two chains termed as alpha and beta subunits. Conodipines are categorized within the group IX of PLA₂s. Here we describe the purification and biochemical characterization of three conodipines (Cdpi-P1, -P2 and -P3) isolated from the injected venom of Conus purpurascens Using proteomics methods, we determined the full sequences of all three conodipines. Conodipine-P1-3 have conserved consensus catalytic domain residues, including the Asp/His dyad. Additionally, these enzymes are expressed as a mixture of proline hydroxylated isoforms. The activities of the native Conodipine-Ps were evaluated by conventional colorimetric and by MS-based methods, which provide the first detailed cone snail venom conodipine activity monitored by mass spectrometry. Conodipines can have medicinal applications such inhibition of cancer proliferation, bacterial and viral infections among others.

Enzymatic properties of starfish phospholipase A2 and its application

Industrial phospholipase A2 (PLA2) mainly produced from porcine pancreas is used for production of lysolecithin which is well known as an excellent natural emulsifier for food, cosmetic, and pharmaceutical industries. Since the outbreak of bovine spongiform encephalopathy (BSE) or religious tradition, it is hoped that the new sources of PLA2, as well as other enzymes and proteins, will be developed instead of mammal. From these backgrounds, we studied for PLA2 from marine organisms and found that starfish Asterina pectinifera PLA2 possesses extremely high activity and characteristic polar-group specificity comparing with commercially available PLA2 from porcine pancreas. Therefore, it was suggested that the starfish A. pectinifera would be a potential source of PLA2, and the PLA2 can be utilized as alternative enzyme of mammalian PLA2.

Marine natural products targeting phospholipases A2

Phospholipases A(2) (PLA(2)s) form a family of enzymes catalyzing the hydrolysis of membrane phospholipids into arachidonic acid, which is the major precursor of pro-inflammatory eicosanoids. As a result, PLA(2)s have been considered as potential targets in anti-inflammatory drug discovery. Marine natural products are a rich source of bioactive compounds, including PLA(2) inhibitors. Here, we review the properties of marine PLA(2) inhibitors identified since the first discovery of PLA(2) inhibitory activity in the marine natural product manoalide in the mid 1980s.

Characterization of phospholipase A(2) activity in serum of the American alligator (Alligator mississippiensis)

PLA(2) is a diverse class of enzymes with a broad spectrum of physiological functions. Secretory PLA(2) isoforms have been reported to exhibit important innate immune function in higher vertebrates. This study was conducted to characterize PLA(2) activity in the serum of the American alligator (Alligator mississippiensis). We used a glycerophospholipid with a fatty acid in the sn-2 position labeled with a fluorescent probe (BODIPY) to detect and quantify alligator serum PLA(2) activity. Incubation of BODIPY-labeled bacteria with different concentrations of alligator serum resulted in a concentration-dependent detection of PLA(2) activity. Kinetic studies showed that product formation was rapid, with substantial activity within 5 min, and maximal activity at approximately 20 min. The alligator PLA(2) activity was temperature-dependent, with activity at lower temperatures (5-10 degrees C) approximately half of that observed at temperatures of 30-40 degrees C. In addition, the generation of fluorescent product was reduced by a specific inhibitor (p-bromophenacyl bromide) of secretory PLA(2) in a concentration-dependent manner, enforcing the idea that the observed activities are due to a secretory PLA(2) enzyme in alligator serum.

Purification and characterization of the biological effects of phospholipase A(2) from sea anemone Bunodosoma caissarum

Sea anemones contain a variety of biologically active substances. Bunodosoma caissarum is a sea anemone from the Cnidaria phylum, found only in Brazilian coastal waters. The aim of the present work was to study the biological effects of PLA(2) isolated from the sea anemone B. caissarum on the isolated perfused kidney, the arteriolar mesenteric bed and on insulin secretion. Specimens of B. caissarum were collected from the São Vicente Channel on the southern coast of the State of São Paulo, Brazil. Reverse phase HPLC analysis of the crude extract of B. caissarum detected three PLA(2) proteins (named BcPLA(2)1, BcPLA(2)2 and BcPLA(2)3) found to be active in B. caissarum extracts. MALDI-TOF mass spectrometry of BcPLA(2)1 showed one main peak at 14.7 kDa. The N-terminal amino acid sequence of BcPLA(2)1 showed high amino acid sequence identity with PLA(2) group III protein isolated from the Mexican lizard (PA23 HELSU, HELSU, PA22 HELSU) and with the honey bee Apis mellifera (PLA(2) and 1POC_A). In addition, BcPLA(2)1 also showed significant overall homology to bee PLA(2). The enzymatic activity induced by native BcPLA(2)1 (20 microg/well) was reduced by chemical treatment with p-bromophenacyl bromide (p-BPB) and with morin. BcPLA(2)1 strongly induced insulin secretion in presence of high glucose concentration. In isolated kidney, the PLA(2) from B. caissarum increased the perfusion pressure, renal vascular resistance, urinary flow, glomerular filtration rate, and sodium, potassium and chloride levels of excretion. BcPLA(2)1, however, did not increase the perfusion pressure on the mesenteric vascular bed. In conclusion, PLA(2), a group III phospholipase isolated from the sea anemone B. caissarum, exerted effects on renal function and induced insulin secretion in conditions of high glucose concentration.

Exploring the antagonistic producer Streptomyces MSI051: implications of polyketide synthase gene type II and a ubiquitous defense enzyme phospholipase A2 in the host sponge Dendrilla nigra

To explore the functional role of the antagonistic producer strain Streptomyces dendra sp. nov. MSI051 in the host sponge Dendrilla nigra, hypothetical factors including the antagonistic potential of MSI051 against biofilm bacteria and a ubiquitous defense enzyme phospholipase A2 (PLA2) in host sponge as well as in bacterial symbiont MSI051 were determined. The host sponge D. nigra and associated bacterial symbiont MSI051 contained high levels of PLA2. The host sponge showed PLA2 activity to the extent of 1032 U/L, with a specific activity of 2021 U/g, and strain MSI051 showed similar activity. The findings of the present study suggest that PLA2 in the sponge-associated bacteria might have an integrated functional role in the host defense system of marine sponges. This report may be the first on the role of PLA2 activity in sponge-associated bacteria. Isolate MSI051 was a potential antagonistic producer which showed a broad spectrum of antibacterial activity. Polyketide synthase gene type II in MSI051 ultimately evidenced the antagonistic potential. Antimicrobial activity was found to be positively skewed toward biofilm bacteria. This implies a functional role of MSI051 in the protection of host sponge against fouling processes.

Comparative study on the cell toxicity and enzymatic activity of two northern scyphozoan species Cyanea capillata (L.) and Cyanea lamarckii (Péron & Léslieur)

Two species of venomous pelagic cnidaria are compared according to their enzymatic, cytotoxic and haemolytic potency. The widely distributed jellyfish Cyanea capillata and Cyanea lamarckii were collected in the North Sea at the coasts of the Orkney Island and the Island of Helgoland. Purified cnidocyst extracts from fishing and mesenteric tentacles were prepared and tested for their bioactivity. The haemolysis induced by toxins of C. capillata was determined with respect to organism size and toxigenic organs. The haemolytic activity of the related species C. lamarckii was documented for the first time. Dose dependent haemolytic activities have been detected by means of protein equivalents at concentrations above 20mug(protein)/mL. Extracts of fishing tentacle cnidocysts showed a less potent haemolytic activity compared to extracts of mesenteric tentacles. In vitro studies with permanent cells of a hepatoma cell line have shown a time and concentration dependent loss of cell vitality up to 90% at 33.3mug(protein)/mL (10mug(protein)/10(5) cells). Supplementing the cell based toxicity tests an enzyme assay was performed to measure a phospholipase A(2) (PLA(2)) activity. A PLA(2)-like activity could be demonstrated in cnidocysts extracts prepared from mesenteric and fishing tentacles of both jellyfish species.

Venom from spiders of the genus Hippasa: biochemical and pharmacological studies

The venoms from female spiders of the genus Hippasa namely H. partita, H. agelenoides and H. lycosina are compared for biochemical and pharmacological properties. SDS-PAGE pattern revealed varied protein composition. Marked variability is seen with casein hydrolyzing enzymes in SDS-PAGE zymogram. H. partita venom was the only venom that hydrolyzed gelatin while the other two venoms did not. The venoms shared similar hyaluronidase activity, showing a single activity band in SDS-PAGE zymogram. The PLA2 activity varied as H. partita>H. agelenoides>H. lycosina venoms. Marked differences were noted in the ability to induce edema, cytotoxicity, myotoxicity and neurotoxicity, while hemorrhage was associated exclusively with H. partita venom.

Effect of calcineurin inhibitors on myotoxic activity of crotoxin and Bothrops asper phospholipase A2 myotoxins in vivo and in vitro

Previous studies have shown that calcineurin activity plays a critical role in the myotoxic activity induced by crotoxin (CTX), a group II phospholipase A(2) (PLA(2)) with neurotoxic and myotoxic actions. In order to address whether calcineurin is also important for the activity of non-neurotoxic group II PLA(2) myotoxins we have compared the effects of calcineurin inhibition on the myotoxic capacity of CTX and the non-neurotoxic PLA(2)s, myotoxin II (Mt II) and myotoxin III (Mt III) from Bothrops asper venom. Rats were treated with cyclosporin A (CsA) or FK506, calcineurin inhibitors, and received an intramuscular injection of either CTX, Mt II or Mt III into the tibialis anterior. Animals were killed 24 h after injection of toxins. Tibialis anterior was removed and stored in liquid nitrogen. Myofibers in culture were also treated with CsA or FK506 and exposed to CTX, Mt II and Mt III. It was observed that, in contrast to CTX, CsA and FK506 do not attenuate myotoxic effects induced by both Mt II and Mt III in vivo and in vitro. The results of the present study suggest that calcineurin is not essential for the myotoxic activity of Mt II and Mt III, indicating that distinct intracellular pathways might be involved in myonecrosis induced by neurotoxic CTX and non-neurotoxic Bothrops sp. PLA(2) myotoxins. Alternatively, calcineurin dependent fast fiber type shift might render the muscle resistant to the action of CTX, without affecting its susceptibility to Bothrops sp. myotoxins.

Bothrops moojeni myotoxin-II, a Lys49-phospholipase A2 homologue: an example of function versatility of snake venom proteins

MjTX-II, a myotoxic phospholipase A(2) (PLA(2)) homologue from Bothrops moojeni venom, was functionally and structurally characterized. The MjTX-II characterization included: (i) functional characterization (antitumoral, antimicrobial and antiparasitic effects); (ii) effects of structural modifications by 4-bromophenacyl bromide (BPB), cyanogen bromide (CNBr), acetic anhydride and 2-nitrobenzenesulphonyl fluoride (NBSF); (iii) enzymatic characterization: inhibition by low molecular weight heparin and EDTA; and (iv) molecular characterization: cDNA sequence and molecular structure prediction. The results demonstrated that MjTX-II displayed antimicrobial activity by growth inhibition against Escherichia coli and Candida albicans, antitumoral activity against Erlich ascitic tumor (EAT), human breast adenocarcinoma (SK-BR-3) and human T leukemia cells (JURKAT) and antiparasitic effects against Schistosoma mansoni and Leishmania spp., which makes MjTX-II a promising molecular model for future therapeutic applications, as well as other multifunctional homologous Lys49-PLA(2)s or even derived peptides. This work provides useful insights into the structural determinants of the action of Lys49-PLA(2) homologues and, together with additional strategies, supports the concept of the presence of others "bioactive sites" distinct from the catalytic site in snake venom myotoxic PLA(2)s.

Molecular cloning of two toxic phospholipases A2 from the crown-of-thorns starfish Acanthaster planci venom

The full-length cDNAs encoding two toxic phospholipases A2 (AP-PLA2-I and -II) from the crown-of-thorns starfish Acanthaster planci venom were individually cloned by RT-PCR, 3'RACE and 5'RACE. In common with both AP-PLA2s, the precursor protein is composed of a signal peptide, a propeptide and a mature protein (136 and 135 residues for AP-PLA2-I and -II, respectively). The four motifs (Ca2+-binding loop, Ca2+-binding site, active site and catalytic network) characteristic of groups I and II PLA2s are well conserved in both AP-PLA2s. In addition to this, the presence of the elapid and pancreatic loops and the involvement of a propeptide in the precursors suggested that AP-PLA2s are highly analogous to the group IB PLA2s. However, when compared to the amino acid sequence of bovine pancreatic PLA2, the representative group IB PLA2, AP-PLA2s require some amino acid insertions and deletions in the region 76-100, as previously observed for the starfish Asterina pectinifera PLA2s. Furthermore, the phylogenetic tree made clearly demonstrated that AP-PLA2s and A. pectinifera PLA2s are distinguishable from the group IB PLA2s as well as other PLA2s, being classified into a new group.

Phospholipase A2 in Cnidaria

Phospholipase A2 (PLA2) is an enzyme present in snake and other venoms and body fluids. We measured PLA2 catalytic activity in tissue homogenates of 22 species representing the classes Anthozoa, Hydrozoa, Scyphozoa and Cubozoa of the phylum Cnidaria. High PLA2 levels were found in the hydrozoan fire coral Millepora sp. (median 735 U/g protein) and the stony coral Pocillopora damicornis (693 U/g) that cause skin irritation upon contact. High levels of PLA2 activity were also found in the acontia of the sea anemone Adamsia carciniopados (293 U/g). Acontia are long threads containing nematocysts and are used in defense and aggression by the animal. Tentacles of scyphozoan and cubozoan species had high PLA2 activity levels: those of the multitentacled box jellyfish Chironex fleckeri contained 184 U/g PLA2 activity. The functions of cnidarian PLA2 may include roles in the capture and digestion of prey and defense of the animal. The current observations support the idea that cnidarian PLA2 may participate in the sting site irritation and systemic envenomation syndrome resulting from contact with cnidarians.

2-Methoxylated fatty acids in marine sponges: Defense mechanism against mycobacteria?

A series of saturated 2-methoxylated FA having even-numbered chains with 8-14 carbons were synthesized, and their spectroscopic data are presented for the first time. The 2-methoxylated C10-C14 acids were prepared from the corresponding 2-hydroxylated FA, whereas the 2-methoxyoctanoic acid was synthesized starting with heptaldehyde. All of the methoxylated FA displayed some degree of inhibition (between 2 and 99%) of Mycobacterium tuberculosis H(37)Rv at 6.25 microg/mL. The most inhibitory FA was 2-methoxydecanoic acid, with a minimum inhibitory concentration of 200-239 microM against M. tuberculosis H(37)Rv as determined by both the microplate Alamar Blue assay and the green fluorescent protein microplate assay. These results are discussed in terms of the possible role of the 2-methoxylated FA as antimicrobial lipids produced either by marine sponges, or the associated marine symbiotic bacteria, as a defense mechanism in a highly competitive environment.