Amino-acid sequence of an alpha-parvalbumin, pI = 4.88, from frog skeletal muscle

Comprehensive Sequence Analysis of Parvalbumins in Fish and Their Comparison with Parvalbumins in Tetrapod Species

Parvalbumins are small molecules with important functions in Ca²⁺ signaling, but their sequence comparisons to date, especially in fish, have been relatively poor. We here, characterize sequence motifs that distinguish parvalbumin subfamilies across vertebrate species, as well as those that distinguish individual parvalbumins (orthologues) in fish, and map them to known parvalbumin structures. As already observed by others, all classes of jawed vertebrates possess parvalbumins of both the α-parvalbumin and oncomodulin subfamilies. However, we could not find convincing phylogenetic support for the common habit of classifying all non-α-parvalbumins together as "β-parvalbumins." In teleost (modern bony) fish, we here distinguish parvalbumins 1-to-10, of which the gene copy number can differ between species. The genes for α-parvalbumins (pvalb6 and pvalb7) and oncomodulins (pvalb8 and pvalb9) are well conserved between teleost species, but considerable variation is observed in their copy numbers of the non-α/non-oncomodulin genes pvalb1-to-5 and pvalb10. Teleost parvalbumins 1-to-4 are hardly distinguishable from each other and are highly expressed in muscle, and described allergens belong to this subfamily. However, in some fish species α-parvalbumin expression is also high in muscle. Pvalb5 and pvalb10 molecules form distinct lineages, the latter even predating the origin of teleosts, but have been lost in some teleost species. The present study aspires to be a frame of reference for future studies trying to compare different parvalbumins.

IgE antibodies of fish allergic patients cross-react with frog parvalbumin

BACKGROUND

The major allergens in fish are parvalbumins. Important immunoglobulin (Ig)E cross-recognition of parvalbumins from different fish species has been shown. Recently frog parvalbumin alpha has been found to be responsible for a case of IgE-mediated anaphylaxis triggered by the ingestion of frog meat. The aim of this study was to investigate whether IgE antibodies of fish allergic persons cross-react with frog parvalbumin and to appreciate its clinical relevance.

METHODS

The sera of 15 fish allergic patients and one fish and frog allergic patient were tested by IgE-immunoblotting against frog muscle extract. Sera were tested against recombinant parvalbumin alpha and beta from Rana esculenta. Skin prick tests were performed in selected patients with recombinant frog parvalbumin. Ca(2+) depletion experiments and inhibition studies with purified cod and frog recombinant parvalbumin were done to characterize the cross-reactive pattern.

RESULTS

Fourteen of the sera tested had IgE antibodies recognizing low molecular weight components in frog muscle extract. Calcium depletion experiments or inhibition of patient sera with purified cod parvalbumin led to a significant or complete decrease in IgE binding. When tested against recombinant parvalbumins, three of 13 sera reacted with alpha parvalbumin and 11 of 12 reacted with beta parvalbumin from R. esculenta. Skin prick tests performed with recombinant frog parvalbumin were positive in fish allergic patients. Inhibition studies showed that a fish and frog allergic patient was primarily sensitized to fish parvalbumin.

CONCLUSION

Cod parvalbumin, a major cross-reactive allergen among different fish species, shares IgE binding epitopes with frog parvalbumin. This in vitro cross-reactivity seems to be also clinically relevant. Parvalbumins probably represent a new family of cross-reactive allergens.

Severe IgE-mediated anaphylaxis following consumption of fried frog legs: definition of alpha-parvalbumin as the allergen in cause

BACKGROUND

IgE-mediated allergic reactions to bullfrog and edible frog have been reported. The implicated allergens have not been defined so far. The frog material and the patient's serum from a case of severe food-induced anaphylaxis were used to define the implicated allergen at the protein and DNA level.

METHODS

Immunoblotting techniques and N-terminal protein microsequencing were used to define the allergen recognized by the patient's serum. Back translation from the identified protein sequence was used to design degenerated primers to amplify the allergen's cDNA by polymerase chain reaction (PCR). We defined the nucleotide sequence of the allergen from the frog of Indonesian origin that was consumed by the patient, and the homologous cDNA from Rana esculenta.

RESULTS

Protein microsequencing revealed that the implicated frog allergen belonged to the parvalbumin family. cDNAs coding for alpha- and beta-parvalbumin of R. esculenta and Rana species were cloned. Recombinant proteins were expressed in Escherichia coli. The patient's serum IgE antibodies recognized parvalbumin prepared from frog muscle and recombinant alpha-parvalbumin from R. species but not from R. esculenta. Recombinant beta-parvalbumin was not recognized by the IgE antibodies.

CONCLUSION

This work defines at the protein and DNA levels alpha-parvalbumin as the allergen implicated in a case of IgE-mediated anaphylaxis to frog muscle. It also shows that a protein belonging to the parvalbumin family is implicated in type I allergies outside the fish species.

The complete amino acid sequence of bullfrog (Rana catesbeiana) parvalbumin pI4.97

The primary structure of the parvalbumin (pI4.97) from bullfrog, Rana catesbeiana, skeletal muscle has been determined. It is composed of 110 amino acid residues and a free amino terminus, and has a molecular mass of 11919. The amino acid sequences which are thought to be functionally important sites are also conserved in the bullfrog parvalbumin. The calculated phylogenic tree indicates that this parvalbumin belongs to the alpha group of parvalbumins. The mutation rate of parvalbumin was fairly rapid in frogs compared to mammals. The subdivergence of frogs is also discussed.

Evolution of EF-hand calcium-modulated proteins. I. Relationships based on amino acid sequences

The relationships among 153 EF-hand (calcium-modulated) proteins of known amino acid sequence were determined using the method of maximum parsimony. These proteins can be ordered into 12 distinct subfamilies--calmodulin, troponin C, essential light chain of myosin, regulatory light chain, sarcoplasmic calcium binding protein, calpain, aequorin, Stronglyocentrotus purpuratus ectodermal protein, calbindin 28 kd, parvalbumin, alpha-actinin, and S100/intestinal calcium-binding protein. Eight individual proteins--calcineurin B from Bos, troponin C from Astacus, calcium vector protein from Branchiostoma, caltractin from Chlamydomonas, cell-division-cycle 31 gene product from Saccharomyces, 10-kd calcium-binding protein from Tetrahymena, LPS1 eight-domain protein from Lytechinus, and calcium-binding protein from Streptomyces--are tentatively identified as unique; that is, each may be the sole representative of another subfamily. We present dendrograms showing the relationships among the subfamilies and uniques as well as dendrograms showing relationships within each subfamily. The EF-hand proteins have been characterized from a broad range of organismal sources, and they have an enormous range of function. This is reflected in the complexity of the dendrograms. At this time we urge caution in assigning a simple scheme of gene duplications to account for the evolution of the 600 EF-hand domains of known sequence.

Heat capacity and entropy changes of the major isotype of the toad (Bufo) parvalbumin induced by calcium binding

The possible structural changes in the major isotype of parvalbumin from the toad (Bufo bufo japonicus) skeletal muscle caused by Ca2+ and Mg2+ binding have been analyzed by microcalorimetric titrations. Parvalbumin was titrated with Ca2+ in both the absence and presence of Mg2+ and with Mg2+ in the absence of Ca2+, at pH 7.0, and at 5 degrees, 15 degrees, and 25 degrees C. The two sites in a molecule were equivalent on Mg2(+)-Ca2+ exchange, but distinguishable on Ca2+ and Mg2+ binding. The reactions of parvalbumin with Ca2+ are exothermic at every temperature in both the absence and presence of Mg2+, but those with Mg2+ are always endothermic except for the binding to site 1 at 25 degrees C. The magnitudes of the hydrophobic and internal vibrational contributions to the heat capacity and entropy changes of parvalbumin on Ca2+ and Mg2+ binding and Mg2(+)-Ca2+ exchange have been estimated by the empirical method of Sturtevant [Sturtevant, J. M. (1977) Proc. Natl Acad. Sci. USA 74, 2236-2240]. Although no major conformational changes were noted between Ca2(+)- and Mg2(+)-bound forms of toad parvalbumin, the conformational difference was larger in Ca2+ (or Mg2+) binding to site 1 than site 2. This may indicate that the metal-free form is much less stable than any form with Ca2+ (or Mg2+) bound at one site at least. On Mg2(+)-Ca2+ exchange, the vibrational as well as hydrophobic entropy is only slightly increased in a parallel manner. In contrast, on Ca2+ (or Mg2+) binding, the hydrophobic entropy increases but the vibrational entropy decreases; the former indicates the sequestering of nonpolar groups from the surface to the interior of a molecule, and the latter suggests that the overall structures are tightened on Ca2+ (or Mg2+) binding but loosened on Mg2(+)-Ca2+ exchange. Despite the clear distinctions in the thermodynamic features, the conformational changes of toad parvalbumin are essentially the same as those of the two isotypes of bullfrog parvalbumins on Ca2+ binding and Mg2(+)-Ca2+ exchange.

Purification and characterization of the parvalbumin from monkey skeletal muscle

1. A high affinity Ca2+ binding and low mol. wt protein, parvalbumin, was purified from monkey skeletal muscle. 2. As compared with other animals, only one component and a lower content of monkey parvalbumin were found. 3. This may suggest that both the component and the content of parvalbumin decreases with biological evolution. 4. The parvalbumin was found to have a mol. wt of 11,400, a pI of 5.1, a high aspartic acid and lysine content, maximum absorption at around 260 nm, a blocked amino-terminal, an immunological distinction, 2 mol Ca2+ binding/mol, and a conformational change by Ca2+ binding. 5. Parvalbumin was shown to have alpha type properties.

Complete amino acid sequence of the sarcoplasmic calcium-binding protein (SCP-I) from crayfish (Astacus leptodactylus)

The complete amino acid sequence of the alpha chain of the dimeric sarcoplasmic Ca2+-binding protein (SCP-I = alpha 2) from crayfish (Astacus leptodactylus) has been determined by partial automatic sequencing of the peptides derived from tryptic digests of the protein after citraconylation or treatment with 1,2-cyclohexanedione. Overlapping peptides were obtained by cleavage with o-iodosobenzoic acid, or digestion with Staphylococcus aureus protease, thermolysin and pepsin. The acetylated N-terminus was identified by fast atom bombardment mass spectrometry. The monomeric protein contains 192 amino acids and has an Mr of 21,643. The sequence shows the presence of three calcium-binding sites and perhaps of two others that may be degenerated.

Two-dimensional 1H nuclear magnetic resonance study of pike pI 5.0 parvalbumin (Esox lucius). Sequential resonance assignments and folding of the polypeptide chain

The structure of alpha pike 5.0 parvalbumin under its Ca-loaded form (or PaCa2) is studied in solution by two-dimensional 1H nuclear magnetic resonance (n.m.r.) at 360 MHz using a conventional strategy of sequential assignments, which involved correlated spectroscopy, relayed coherence transfer spectroscopy and nuclear Overhauser enhancement spectroscopy. In order to overcome the problem of spectral overlapping due to the presence of 108 residues in the protein, experiments were performed at different pH and temperature values, either in 1H2O or in 2H2O solutions. The amino acid sequence of pike 5.0 parvalbumin is thus fully characterized by nearly the totality of its NH, C alpha H and C beta H resonances originating from the different residues (421 protons assigned among 429 in total). When associated with the remaining side resonances, these sequence-specific assignments provide a basis for establishing the secondary organization and tertiary folding of the polypeptide chain. Pike 5.0 parvalbumin was selected as a characteristic representative of the alpha phylogenic series, for which no crystalline structure is presently available, in contrast with the beta series for which two crystalline structures have been determined. A parvalbumin molecule with a single polypeptide chain of 108 amino acids represents one of the highest molecular weights analyzed so far by two-dimensional n.m.r. spectroscopy. The use of a moderate magnetic field strength, with 1H nuclei resonating at 360 MHz, is justified by the fact that ring current effects are operating favorably in this globular protein with a high phenylalanine content. A three-dimensional structure has been generated by the "distance geometry" or DISGEO computational procedure on the basis of about 450 interproton nuclear Overhauser enhancement connectives (short, medium and long-range) in conjunction with a selection of phi and chi dihedral angle constraints. The coherence of the calculated structure, which displays all the features of the typical folding of a parvalbumin protein, provides a good test of reliability of the n.m.r. data collected so far. Although similar to a beta parvalbumin in the folding of its polypeptide chain, the alpha parvalbumin studied here differs markedly from a beta parvalbumin in the length of its C-terminal F-helix domain, which includes 11 residues instead of ten in the latter.(ABSTRACT TRUNCATED AT 400 WORDS)

Theoretical estimation of the calcium-binding constants for proteins from the troponin C superfamily based on a secondary structure prediction method. I. Estimation procedure

Proteins belonging to the TNC superfamily are known to be built of two, three, four, or six domains of closely similar amino acid sequences. Each domain binds no more than one calcium ion and shows a characteristic helix-loop-helix structure when in the calcium-bound state. Conformational properties of all the domains known so far have been analysed by us using a secondary structure prediction method (Garnier, J., Osguthorpe, D.J. & Robson, B. (1978). J. molec. Biol. 120, 97). Significant differences in distribution of residues predicted as being in the helical, beta-turn, and coil conformations have been found between the strongly, weakly, and non-binding domains. We could determine the ideal prediction pattern characteristic for the domains with the highest affinity for calcium. On the basis of our analysis and observations made by other authors we worked out a few simple rules which made it possible to compare conformational properties of a given domain with the ideal reference pattern and estimate, in this way, the Ca2+-binding constant of the domain. In native proteins the domains are known to be organized in pairs. The Ca2+-binding constant for a two-domain region could be evaluated from the sum of the estimation points attributed to each of its components. Using our method it is possible to predict the binding constants of typical domains and two-domain regins with a precision of one order of magnitude. Data on amino acid sequences and calcium-binding constants of all known proteins, believed to be the members of the TNC superfamily, have been reviewed. References to virtually all papers published on this subject before the end of 1987 are given.

Fast atom bombardment mass spectra of various peptides from sarcoplasmic calcium-binding protein

The sarcoplasmic calcium-binding protein of the crayfish Astacus leptodactylus is a calciprotein. The primary structure of this protein has been determined. Tryptic digestion of the denaturated protein followed by high-performance liquid chromatographic separation identified essentially eight peptides. The structure of these peptides has been confirmed after amino acid analysis by fast atom bombardment spectra in positive mode.

Expression of the Ca2+-binding protein, parvalbumin, during embryonic development of the frog, Xenopus laevis

A cDNA segment encoding the Ca2+-binding protein, parvalbumin, was isolated with the use of antibodies, from a lambda gtll expression library of Xenopus laevis tadpole poly(A)+ RNAs. The bacterially expressed beta-galactosidase-parvalbumin fusion protein of one lambda recombinant shows high affinity 45Ca2+ binding. The sequence of the tadpole parvalbumin is highly similar to previously characterized beta-parvalbumins of other organisms. Data from protein and RNA blotting experiments demonstrate that parvalbumin is absent in oocytes, eggs, and early staged embryos, and only becomes expressed during embryogenesis at the time of myogenesis. The protein can be detected in individual developing muscle cells and in muscle fibers of tadpole tail muscles. A simple method is also described for the isolation of neural tube-notochord-somite complexes from Xenopus embryos.

A calorimetric study of Ca2+ binding by the parvalbumin of the toad (Bufo): distinguishable binding sites in the molecule

Microcalorimetric titrations of the major isotype of parvalbumin (tPA) from toad (Bufo) skeletal muscle, with Ca2+ in the presence and absence of Mg2+ and with Mg2+ in the absence of Ca2+, have been carried out at 25 degrees C and pH 7.0. The results indicate that the two binding sites in each molecule are distinguishable from each other for both Ca2+ binding and Mg2+ binding. Such a characteristic is distinctly different from those of other parvalbumins. The enthalpy changes determined are distinctly different from those of bullfrog parvalbumins on Ca2+ or Mg2+ binding, but are similar to those on Mg2+-Ca2+ exchange. The results indicate that the reaction of Mg2+-Ca2+ exchange is driven almost entirely by the large favorable enthalpy change.

Antigenic probes locate the myosin subfragment 1 interaction site on the N-terminal part of actin

The interaction of two different anti-actin antibody populations with the myosin subfragment 1-F-actin rigor complex has been studied. In contrast with the 1-7 sequence, the 18-28 sequence appears to be strongly implicated in the contact area of the myosin head on the actin polypeptide chain.

Structural variations in actins. Biochemical and immunological tools for probing the structure of rabbit skeletal-muscle and bovine aortic actins

Structural differences between skeletal-muscle and aortic actins were studied by using biochemical and immunological approaches. By using proteinase digestion we found that three regions of actin show structural differences: (a) in the C-terminal part, (b) the region around residue 227 and (c) the region around residue 167. By using antibodies specific to particular actin conformations we can discriminate between monomeric and filamentous forms of the two actins. Our results show that the minor sequence variations of the N- and C-terminal regions induce structural change in these regions, but also some long-range structural variations in other regions.

A calorimetric study of Ca2+ binding to two major isotypes of bullfrog parvalbumin

Microcalorimetric titrations of the two major isotypes of parvalbumin (PA1 and PA2) from bullfrog skeletal muscle with Ca2+ in the presence and absence of Mg2+ have been carried out at 25 degrees C and pH 7.0. The observed enthalpy titration curves were analyzed by the least-squares method. The measured enthalpy changes (delta H) of Ca2+ binding are -33.2 (PA1) and -16.3 kJ/mol site (PA2), and the entropy changes (delta S) are 28 (PA1) and 76 j/mol per K (PA2) in the absence of Mg2+. When 5 mM Mg2+ is present, the enthalpy change of PA2 (-26.7 kJ/mol) is about twice as large as that in the absence of Mg2+, whereas that of PA1 (-34.6 kJ/mol) is about the same. The entropy changes are 8 (PA1) and 29 J/mol per K (PA2). Both enthalpy and entropy changes are favorable for the Ca2+-binding reactions of PA1 and PA2 irrespective of the presence of Mg2+.

Conformational changes induced by Mg2+ on actin monomers. An immunologic attempt to localize the affected region

The effect of Mg2+ ions on the conformation of G-actin and in particular on the accessibility of its antigenic regions has been tested. Experiments were performed with G-actin coupled to Sepharose 4B which was, therefore, maintained in the monomeric state. The results presented her show that the 2mM MgCl2-perturbed antigenic site is located in a central region of the actin sequence.

The complete amino acid sequence of oncomodulin--a parvalbumin-like calcium-binding protein from Morris hepatoma 5123tc

Oncomodulin is an acidic calcium-binding protein of 108 amino acids which has been detected only in tumors. The complete amino acid sequence of rat oncomodulin has been established, and the N-terminus shown to be N-acetylserine. Homology of the oncomodulin sequence with members of the troponin C superfamily of calcium-binding proteins was demonstrated, and putative calcium-binding domains were located. A further degree of homology was established between oncomodulin and the parvalbumins, including rat parvalbumin. Oncomodulin was therefore considered to be a parvalbumin-like calcium-binding protein.

Ion binding to calmodulin. A comparison with other intracellular calcium-binding proteins

Over the past few years calcium has emerged as an important bioregulator. Upon external stimulation, the cell generates a transient Ca2+ increase, which is transformed into a cellular event through a molecular cascade. The first step in this cascade is the binding of calcium to proteins present in the cytosol. These proteins capable of binding Ca2+ under physiological conditions all belong to the same evolutionary family that evolved from a common ancestor. However, they strongly differ in the properties of their calcium binding sites. Calmodulin, the ubiquitous calcium binding protein present in all eukaryotic cells, is very close to the ancestor protein, presents four calcium binding sites which bind calcium, magnesium and monovalent ions competitively and is involved in the triggering of cellular processes. Parvalbumin, another member of the family, is more specialized and found mostly in fast-twitch skeletal muscle. It binds calcium and magnesium with high affinity and seems to be involved in muscle relaxation. On the other hand, troponin C which confers Ca2+ sensitivity to acto-myosin interaction exhibits both triggering and relaxing sites. The study of intracellular Ca2+ binding proteins has shown that calcium binding proteins have evolved from a simple common structure to fulfill different functions.