Cloning and sequence analysis of the cDNA for arginine kinase of lobster muscle

A comprehensive review of arginine kinase proteins: What we need to know?

The enzyme arginine kinase (AK), EC 2.7.3.3, catalyzes the reversible phosphorylation of arginine with adenosine triphosphate, forming phosphoarginine, which acts as an energy reservoir due to its high-energy phosphate content that can be rapidly transferred to ADP for ATP renewal. It has been proposed that AK should be associated with some ATP biosynthesis mechanisms, such as glycolysis and oxidative phosphorylation. Arginine kinase is an analogue of creatine kinase found in vertebrates. A literature survey has recovered the physicochemical and structural characteristics of AK. This enzyme is widely distributed in invertebrates such as protozoa, bacteria, porifera, cnidaria, mollusca, and arthropods. Arginine kinase may be involved in the response to abiotic and biotic stresses, being up regulated in several organisms and controlling energy homeostasis during environmental changes. Additionally, phosphoarginine plays a role in providing energy for the transport of protozoa, the beating of cilia, and flagellar movement, processes that demand continuous energy. Arginine kinase is also associated with allergies to shellfish and arthropods, such as shrimp, oysters, and cockroaches. Phenolic compounds such as resveratrol, which decrease AK activity by 50 % in Trypanosoma cruzi, inhibit the growth of the epimastigote and trypomastigote forms, making them a significant target for the development of medications for Chagas Disease treatment.

Biochemical and structural characterization of a novel arginine kinase from the spider Polybetes pythagoricus

Energy buffering systems are key for homeostasis during variations in energy supply. Spiders are the most important predators for insects and therefore key in terrestrial ecosystems. From biomedical interest, spiders are important for their venoms and as a source of potent allergens, such as arginine kinase (AK, EC 2.7.3.3). AK is an enzyme crucial for energy metabolism, keeping the pool of phosphagens in invertebrates, and also an allergen for humans. In this work, we studied AK from the Argentininan spider Polybetes pythagoricus (PpAK), from its complementary DNA to the crystal structure. The PpAK cDNA from muscle was cloned, and it is comprised of 1068 nucleotides that encode a 384-amino acids protein, similar to other invertebrate AKs. The apparent Michaelis-Menten kinetic constant (K_m) was 1.7 mM with a k_cat of 75 s⁻¹. Two crystal structures are presented, the apoPvAK and PpAK bound to arginine, both in the open conformation with the active site lid (residues 310–320) completely disordered. The guanidino group binding site in the apo structure appears to be organized to accept the arginine substrate. Finally, these results contribute to knowledge of mechanistic details of the function of arginine kinase.

Characterization of Arginine Kinase in the Barnacle Amphibalanus Amphitrite and Its Role in the Larval Settlement

Energy metabolism is a key process in larval settlement of barnacles, but the underlying molecular mechanisms remain ambiguous. Arginine kinase (AK) mainly participates in energy metabolism in invertebrates. So far, its roles in barnacles have not been studied. In the present study, we raised an antibody against AK from Amphibalanus amphitrite Darwin to characterize the roles of AK in the larval settlement process. Among the developmental stages, AK was highly expressed during the cypris stage. Along with the aging process in cyprids, the level of AK decreased. The immunostaining results showed that AK was localized to muscular tissues in cyprids, including antennules, antennular muscles, and thoracic limbs. The larval settlement rate decreased and larval movement was inhibited in response to treatments with high concentrations of AK inhibitors (rutin and quercetin). These results demonstrated that AK was involved in the larval settlement of A. amphitrite through mediating energy supply in muscle tissues. Moreover, further analysis indicated that both the p38 MAPK and NO/cGMP pathways positively mediated the expression of AK in cyprids.

Selectivity of a translation-inhibitory factor, CpBV15β, in host mRNAs and subsequent alterations in host development and immunity

An endoparasitoid wasp, Cotesia plutellae, parasitizes young larvae of the diamondback moth, Plutella xylostella. Its symbiotic virus, C. plutellae bracovirus (CpBV), has been shown to play a crucial role in inducing physiological changes in the parasitized host. A viral gene, CpBV15β, exhibits a specific translational control against host mRNAs by sequestering a eukaryotic translation initiation factor, eIF4A. Inhibitory target mRNAs have high thermal stability (>≈9 kcal/mol) of their secondary structures in 5'UTR. To determine the specificity of translational control in terms of 5'UTR complexity, this study screened target/nontarget mRNAs of CpBV15β using a proteomics approach through an in vivo transient expression technique. A proteomics analysis of host plasma proteins showed that 12.9% (23/178) spots disappeared along with the expression of CpBV15β. A total of ten spots were chosen, in which five spots ('target') were disappeared by expression of CpBV15β and the other five ('nontarget') were insensitive to expression of CpBV15β, and further analyzed by a tandem mass spectroscopy. The predicted genes of target spots had much greater complexity (-12.3 to -25.2 kcal/mol) of their 5'UTR in terms of thermal stability compared to those (-3.70 to -9.00 kcal/mol) of nontarget spots. 5'UTRs of one target gene (arginine kinase:Px-AK) and one nontarget gene (imaginal disc growth factor:Px-IDGF) were cloned and used for in vitro translation (IVT) assay using rabbit reticulocyte lysate. IVT assay clearly showed that mRNA of Px-IDGF was translated in the presence of CpBV15β, but mRNA of Px-AK was not. Physiological significance of these two genes was compared in immune and development processes of P. xylostella by specific RNA interference (RNAi). Under these RNAi conditions, suppression of Px-AK exhibited much more significant adverse effects on larval immunity and larva-to-pupa metamorphosis compared to the effect of suppression of Px-IDGF. These results support the hypothesis that 5'UTR complexity is a molecular motif to discriminate host mRNAs by CpBV15β for its host translational control and suggest that this discrimination would be required for altering host physiology to accomplish a successful parasitism of the wasp host, C. plutellae.

Molecular and biochemical characterisation of arginine kinases in Haemonchus contortus and Teladorsagia circumcincta

Full length cDNA encoding arginine kinases (AK) were cloned from Teladorsagia circumcincta (TcAK) and Haemonchus contortus (HcAK). The TcAK and HcAK cDNA (1080 bp) encoded 360 amino acid proteins. The predicted amino acid sequence showed 99% similarity with each other and 94% with a Caenorhabditis elegans AK. Soluble N-terminal His-tagged AK proteins were expressed in Escherichia coli strain BL21, purified and characterised. All binding sites were completely conserved in both proteins. The recombinant TcAK and HcAK had very similar kinetic properties: K(m) arginine was 0.35 mM, K(m) ATP was 0.8-0.9 mM and the pH optima were pH 7.5. Arginine analogues strongly inhibited recombinant enzyme activities (up to 80%), whilst other amino acids decreased activities by a maximum of 20%. TcAK and HcAK are potential vaccine candidates because of the strong antigenicity of invertebrate phosphagens and kinases and presence in metabolically active parts of the worm.

Crystallization and X-ray diffraction studies of arginine kinase from the white Pacific shrimp Litopenaeus vannamei

Crystals of an unligated monomeric arginine kinase from the Pacific whiteleg shrimp Litopenaeus vannamei (LvAK) were successfully obtained using the microbatch method. Crystallization conditions and preliminary X-ray diffraction analysis to 1.25 Å resolution are reported. Data were collected at 100 K on NSLS beamline X6A. The crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 56.5, b = 70.2, c = 81.7 Å. One monomer per asymmetric unit was found, with a Matthews coefficient (V(M)) of 2.05 Å(3) Da(-1) and 40% solvent content. Initial phases were determined by molecular replacement using a homology model of LvAK as the search model. Refinement was performed with PHENIX, with final R(work) and R(free) values of 0.15 and 0.19, respectively. Biological analysis of the structure is currently in progress.

Arginine kinase is highly expressed in a resistant strain of silkworm (Bombyx mori, Lepidoptera): Implication of its role in resistance to Bombyx mori nucleopolyhedrovirus

A gene encoding Bombyx mori arginine kinase (BmAK) has been indentified differentially expressed in the midguts of Bombyx mori strain NB which is resistant to nucleopolyhedrovirus (BmNPV), strain 306 which is susceptible to NPV and a near isogenic line BC(8) with similar genetic background to 306 but resistant to NPV by two-dimensional gel electrophoresis (2-DE). In this study, we characterized the expression profiles of BmAK using RT-PCR and real-time quantitative PCR. The expression level of BmAK fluctuated in various developing stage and various tissue. Remarkably, the expression level of BmAK increased more than 10-fold 24 hours post inoculation (h p.i.) of NPV in strain NB and BC(8), while such increment was abraded in strain 306 although the basal expression level of BmAK in strain 306 was higher than that of strain NB and BC(8). Western blotting analysis using polyclonal antibody against BmAK verified such observation, and immunofluoresence analysis indicated for the first time that BmAK was mainly located to the cytoplasm or some structures in cytoplasm. These findings suggest that arginine kinase is involved in the antiviral process of Bombyx mori larvae against NPV infection.

The encysted dormant embryo proteome of Artemia sinica

The possibility of the brine shrimp Artemia to produce dormant embryo (cysts) in diapause is a key feature in its life history. In the present study, we obtained a proteomic reference map for the diapause embryo of Artemia sinica using two-dimensional gel electrophoresis with a pH range of 4-7 and a molecular weight range of 10-100 kDa. Approximately 233 proteins were detected, and 60 of them were analyzed by capillary liquid chromatography tandem mass spectrometry (LC-MS/MS). Of these, 39 spots representing 33 unique proteins were identified, which are categorized into functional groups, including cell defense, cell structure, metabolism, protein synthesis, proteolysis, and other processes. This reference map will contribute toward understanding the state of the diapause embryo and lay the basis and serve as a useful tool for further profound studies in the proteomics of Artemia at different developmental stages and physiological conditions.

Discovery of the genes in response to white spot syndrome virus (WSSV) infection in Fenneropenaeus chinensis through cDNA microarray

We used microarray technology to study differentially expressed genes in white spot syndrome virus (WSSV)-infected shrimp. A total of 3136 cDNA targets, including 1578 unique genes from a cephalothorax cDNA library and 1536 cDNA clones from reverse and forward suppression subtractive hybridization (SSH) libraries of Fenneropenaeus chinensis, plus 14 negative and 8 blank control clones, were spotted onto a 18 x 18 mm area of NH(2)-modified glass slides. Gene expression patterns in the cephalothorax of shrimp at 6 h after WSSV injection and moribund shrimp naturally infected by WSSV were analyzed. A total of 105 elements on the arrays showed a similar regulation pattern in artificially infected shrimp and naturally infected moribund shrimp; parts of the results were confirmed by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). The up-regulated expression of immune-related genes, including heat shock proteins (HSP70 and HSP90), trehalose-phosphate synthase (TPS), ubiquitin C, and so forth, were observed when shrimp were challenged with WSSV. Genes including myosin LC2, ATP synthase A chain, and arginine kinase were found to be down-regulated after WSSV infection. The expression of housekeeping genes such as actin, elongation factor, and tubulin is not stable, and so these genes are not suitable as internal standards for semiquantitative RT-PCR when shrimp are challenged by WSSV. As a substitute, we found that triosephosphate isomerase (TPI) was an ideal candidate of interstandards in this situation.

Expression, purification, and characterization of arginine kinase from the sea cucumber Stichopus japonicus

The arginine kinase gene of sea cucumber Stichopus japonicus was cloned and inserted into the prokaryotic expression plasmid pET-21b. The protein was expressed in a soluble and functional form in Escherichia coli and purified by Blue Sepharose CL-6B, DEAE-32, and Sephadex G-100 chromotography with a final yield of 83 mgL(-1) of LB medium. The specific activity, electrophoretic mobility, and isoelectric focusing were all identical with those of arginine kinase that was purified from sea cucumber muscle. The fluorescence emission spectrum of arginine kinase had a maximum fluorescence at a wavelength of 330 nm upon excitation at 295 nm. These results are the first report of this purified protein.

Functional consequences of a gene duplication and fusion event in an arginine kinase

Arginine kinase (AK) from the foot of the razor clam Ensis directus consists of two full-length AK domains, denoted D1 and D2, fused in a single polypeptide chain. The full-length cDNA for Ensis AK was obtained and its deduced amino acid sequence was analyzed in the context of the X-ray crystal structure of a typical, monomeric AK. Both domains of Ensis AK contain most of the residues currently thought to be critical in catalysis, suggesting that both AK domains are catalytically competent. The full-length Ensis AK, a D2-NusA-His-tag fusion protein and a D2-truncated AK (enterokinase cleavage product of the fusion protein) were expressed in Escherichia coli and purified. All recombinant AK constructs displayed high enzyme activity. Attempts at expressing active D1 alone, D2 alone or a D1-NusA-His-tag fusion protein were unsuccessful. The catalytic properties of the active proteins were compared with the corresponding properties of recombinant AK from the horseshoe crab Limulus polyphemus, which is a typical monomeric AK. In contrast to expectations, the kinetic results strongly suggest that Ensis AK has only one active domain, namely D2. The K(cat) values for all Ensis constructs were roughly twice that of typical AKs, indicating higher overall catalytic throughput at the competent active site. Furthermore, both the full-length and truncated D2 Ensis AKs showed no synergism of substrate binding unlike typical AKs. The D2-NusA-His-tag fusion construct actually displayed negative synergism of substrate binding, which means that, in effect, the first substrate bound acts as a competitive inhibitor of the second. The conservation of the structure of the apparently inactive D1 may be related to constraints imposed by structural changes that could potentially impact substrate binding in D2 and/or possibly influence the proper folding of the enzyme during synthesis. Overall, the results from the present study indicate that the AK contiguous dimer from Ensis directus functions with activity in only the second domain. Although lacking activity in D1, D2 appears to compensate by having a higher intrinsic catalytic throughput than typical 40-kDa monomeric AKs.

Proteomics and immunological analysis of a novel shrimp allergen, Pen m 2

Shellfish are a common cause of adverse food reactions in hypersensitive individuals and shrimp is one of the most frequently reported causes of allergic reactions. A novel allergen from Penaeus monodon, designated Pen m 2, was identified by two-dimensional immunoblotting using sera from subjects with shrimp allergy, followed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of the peptide digest. This novel allergen was then cloned and the amino acid sequence deduced from the cDNA sequence. The cloned cDNA encoded a 356-aa protein with an acetylated N terminus at Ala2, identified by postsource decay analysis. Comparison of the Pen m 2 sequence with known protein sequences revealed extensive similarity with arginine kinase (EC 2.7.3.3) from crustaceans. Pen m 2 was purified by anion exchange chromatography and shown to have arginine kinase activity and to react with serum IgE from shrimp allergic patients and induce immediate type skin reactions in sensitized patients. Using Pen m 2-specific antisera and polyclonal sera from shrimp-sensitive subjects in a competitive ELISA inhibition assay, Pen m 2 was identified as a novel cross-reactive Crustacea allergen. This novel allergen could be useful in allergy diagnosis and in the treatment of Crustacea-derived allergic disorders.

Molecular and immunological characterization of arginine kinase from the Indianmeal moth, Plodia interpunctella, a novel cross-reactive invertebrate pan-allergen

IgE recognition of indoor allergens represents a major cause of allergic asthma in atopic individuals. We found that 52 of 102 patients suffering from allergic symptoms indoors contained IgE Abs against allergens from the Indianmeal moth (Plodia interpunctella), a ubiquitous food pest. Using serum IgE from a moth-sensitized patient we screened an expression cDNA library constructed from P. interpunctella larvae. cDNAs coding for arginine kinase (EC 2.7.3.3), a 40-kDa enzyme commonly occurring in invertebrates that is involved in the storage of such high-energy phosphate bonds as phosphoarginine, were isolated. Recombinant moth arginine kinase, designated Plo i 1, was expressed in Escherichia coli as a histidine-tagged protein with enzymatic activity, and purified to homogeneity by nickel chelate affinity chromatography. Purified recombinant arginine kinase induced specific basophil histamine release and immediate as well as late-phase skin reactions. It reacted with serum IgE from 13 of the 52 (25%) moth-allergic patients and inhibited the binding of allergic patients' IgE to an immunologically related 40-kDa allergen present in house dust mite, cockroach, king prawn, lobster, and mussel. Our results indicate that arginine kinases represent a new class of cross-reactive invertebrate pan-allergens. Recombinant arginine kinase may be used to identify a group of polysensitized indoor allergic patients and for immunotherapy of these individuals.

Expression of arginine kinase enzymatic activity and mRNA in gills of the euryhaline crabs Carcinus maenas and Callinectes sapidus

Phosphagen kinases catalyze the reversible dephosphorylation of guanidino phosphagens such as phosphocreatine and phosphoarginine, contributing to the restoration of adenosine triphosphate concentrations in cells experiencing high and variable demands on their reserves of high-energy phosphates. The major invertebrate phosphagen kinase, arginine kinase, is expressed in the gills of two species of euryhaline crabs, the blue crab Callinectes sapidus and the shore crab Carcinus maenas, in which energy-requiring functions include monovalent ion transport, acid-base balance, nitrogen excretion and gas exchange. The enzymatic activity of arginine kinase approximately doubles in the ion-transporting gills of C. sapidus, a strong osmoregulator, when the crabs are transferred from high to low salinity, but does not change in C. maenas, a more modest osmoregulator. Amplification and sequencing of arginine kinase cDNA from both species, accomplished by reverse transcription of gill mRNA and the polymerase chain reaction, revealed an open reading frame coding for a 357-amino-acid protein. The predicted amino acid sequences showed a minimum of 75 % identity with arginine kinase sequences of other arthropods. Ten of the 11 amino acid residues believed to participate in arginine binding are completely conserved among the arthropod sequences analyzed. An estimation of arginine kinase mRNA abundance indicated that acclimation salinity has no effect on arginine kinase gene transcription. Thus, the observed enhancement of enzyme activity in C. sapidus probably results from altered translation rates or direct activation of pre-existing enzyme protein.

Induced fit in arginine kinase

Creatine kinase (CK) and arginine kinase (AK) are related enzymes that reversibly transfer a phosphoryl group between a guanidino compound and ADP. In the buffering of ATP energy levels, they are central to energy metabolism and have been paradigms of classical enzymology. Comparison of the open substrate-free structure of CK and the closed substrate-bound structure of AK reveals differences that are consistent with prior biophysical evidence of substrate-induced conformational changes. Large and small domains undergo a hinged 13 degrees rotation. Several loops become ordered and adopt different positions in the presence of substrate, including one (residues 309-319) that moves 15 A to fold over the substrates. The conformational changes appear to be necessary in aligning the two substrates for catalysis, in configuring the active site only when productive phosphoryl transfer is possible, and excluding water from the active site to avoid wasteful ATP hydrolysis.

Structural and functional implications of the amino acid sequences of dimeric, cytoplasmic and octameric mitochondrial creatine kinases from a protostome invertebrate

The cDNA and deduced amino-acid sequences for dimeric and octameric isoforms of creatine kinase (CK) from a protostome, the polychaete Chaetopterus variopedatus, were elucidated and then analysed in the context of available vertebrate CK sequences and the recently determined crystal structure of chicken sarcomeric mitochondrial CK (MiCK). As protostomes last shared a common ancestor with vertebrates roughly 700 million years ago, observed conserved residues may serve to confirm or reject contemporary hypotheses about the roles of particular amino acids in functional/structural processes such as dimer/octamer formation and membrane binding. The isolated cDNA from the dimeric CK consisted of 1463 nucleotides with an open reading frame of 1116 nucleotides encoding a 372-amino-acid protein having a calculated molecular mass of 41.85 kDa. The percentage identity of C. variopedatus dimeric CK to vertebrate CK is as high as 69%. The octameric MiCK cDNA is composed of 1703 nucleotides with an open reading frame of 1227 nucleotides. The first 102 nucleotides of the open reading frame encode a 34-amino-acid leader peptide whereas the mature protein is composed of 375 amino acids with a calculated molecular mass of 42.17 kDa. The percentage identity of C. variopedatus MiCK to vertebrate CK is as high as 71%. This similarity is also evident in residues purported to be important in the structure and function of dimeric and octameric CK: (a) presence of seven basic amino acids in the C-terminal end thought to be important in binding of MiCK to membranes; (b) presence of a lysine residue (Lys110 in chicken MiCK) also thought to be involved in membrane binding; and (c) presence of a conserved tryptophan thought to be important in dimer stabilization which is present in all dimeric and octameric guanidino kinases. However, C. variopedatus MiCK lacks the N-terminal heptapeptide present in chicken MiCK, which is thought to mediate octamer stabilization. In contrast with vertebrate MiCK, polychaete octamers are very stable indicating that dimer binding into octamers may be mediated by additional and/or other residues. Phylogenetic analyses showed that both octamer and dimer evolved very early in the CK lineage, well before the divergence of deuterostomes and protostomes. These results indicate that the octamer is a primitive feature of CK rather than being a derived and advanced character.

O-Crystallin, arginine kinase and ferritin from the octopus lens

Three proteins have been identified in the eye lens of the octopus, Octopus dofleini. A 22 kDa protein comprising 3-5% of the soluble protein of the lens is 35-43% identical to a family of phosphatidylethanolamine-binding proteins of vertebrates. Other members of this family include the immunodominant antigen of the filarial parasite, Onchocerca volvulus, putative odorant-binding proteins of Drosophila and a protein with unknown function of Caenorhabditis elegans. We have called this protein O-crystallin on the basis of its abundance in the transparent lens. O-Crystallin mRNA was detected only in the lens. Two tryptic peptides of another octopus lens protein, less abundant than O-crystallin, showed 80% identity to arginine kinase of invertebrates, a relative of creatine kinase of vertebrates. Finally, ferritin cDNA was isolated as an abundant cDNA from the octopus lens library. Northern blots showed that ferritin mRNA is not lens-specific.

Crystal structure of rabbit muscle creatine kinase

The crystal structure of rabbit muscle creatine kinase, solved at 2.35 A resolution by X-ray diffraction methods, clearly identified the active site with bound sulfates surrounded by a constellation of arginine residues. The putative binding site of creatine, which is occupied by a sulfate group in this analysis, has been tentatively identified. The dimeric interface of the enzyme is held together by a small number of hydrogen bonds.

Transition state structure of arginine kinase: implications for catalysis of bimolecular reactions

Arginine kinase belongs to the family of enzymes, including creatine kinase, that catalyze the buffering of ATP in cells with fluctuating energy requirements and that has been a paradigm for classical enzymological studies. The 1.86-A resolution structure of its transition-state analog complex, reported here, reveals its active site and offers direct evidence for the importance of precise substrate alignment in the catalysis of bimolecular reactions, in contrast to the unimolecular reactions studied previously. In the transition-state analog complex studied here, a nitrate mimics the planar gamma-phosphoryl during associative in-line transfer between ATP and arginine. The active site is unperturbed, and the reactants are not constrained covalently as in a bisubstrate complex, so it is possible to measure how precisely they are pre-aligned by the enzyme. Alignment is exquisite. Entropic effects may contribute to catalysis, but the lone-pair orbitals are also aligned close enough to their optimal trajectories for orbital steering to be a factor during nucleophilic attack. The structure suggests that polarization, strain toward the transition state, and acid-base catalysis also contribute, but, in contrast to unimolecular enzyme reactions, their role appears to be secondary to substrate alignment in this bimolecular reaction.

Arginine kinase is highly expressed in the compound eye of the honey bee, Apis mellifera

We have cloned and sequenced a 1.68-kb cDNA encoding arginine kinase in the honey bee, Apis mellifera. The predicted protein shows a high level of identity to known arginine kinases in invertebrates and to other proteins belonging to the conserved family of ATP: guanidino phospho-transferases. The pattern of expression of arginine kinase has been investigated for the first time in various tissues including the brain, antennae and compound eye. Our results show that three isoforms of arginine kinase, transcribed from a single gene, are expressed in a characteristic pattern in major tissues of the honey bee. Arginine kinase mRNA is relatively abundant in the central nervous system and in the antennae. However, the highest level of expression, that is at least two to three times higher than in the brain, is found in the compound eye of the bee. By contrast, the levels of mRNAs encoding another metabolically important enzyme, alpha-glycerolphosphate dehydrogenase (alpha-GPDH), are low in the eye. These findings suggest that arginine kinase is an important component of the energy releasing mechanism in the visual system that has high and fluctuating energy demands. Furthermore, our results support the role of phosphagen kinases in energy transport in polarised cells and are consistent with the role of arginine kinase as an energy shuttle that delivers ATP generated by mitochondria to high energy-requiring processes, such as massive membrane turnover and pigment regeneration in the retina.

Evolution of phosphagen kinase. VI. Isolation, characterization and cDNA-derived amino acid sequence of lombricine kinase from the earthworm Eisenia foetida, and identification of a possible candidate for the guanidine substrate recognition site

Lombricine kinase (LK) from the body wall muscle of the earthworm Eisenia foetida was purified to homogeneity. The enzyme was shown to be a dimer consisting of 40 kDa subunits. The cDNA-derived amino acid sequence of 370 residues of Eisenia LK was determined. The validity of the sequence was supported by chemical sequencing of internal tryptic peptides. This is the first reported lombricine kinase amino acid sequence. Alignment of Eisenia LK with those of creatine kinases (CKs), arginine kinases (AKs) and glycocyamine kinase (GK) suggested a region displaying remarkable amino acid deletions (referred to GS region), as a possible candidate for guanidine substrate recognition site. A phylogenetic analysis using amino acid sequences of all four phosphagen kinases indicates that CK, GK and LK probably evolved from a common immediate ancestor protein.

Purification, characterization, and hydrodynamic properties of arginine kinase from gulf shrimp (Penaeus aztecus)

Arginine kinase from the tail muscle of the Gulf shrimp (Penaeus aztecus) was purified to apparent homogeneity, using a rapid, high-yield method. The protein exhibits a molecular weight of 40 kDa according to the methods of gel filtration and gel electrophoresis in sodium dodecyl sulfate, also indicating that arginine kinase from shrimp is a monomer. The amino acid content of arginine kinase from shrimp is similar to arginine kinases from several species and to creatine kinase from rabbit muscle. Arginine kinase derivatized at the reactive sulfhydryl with 2-(4'-(iodoacetamido)anilino)naphthalene-6-sulfonic acid exhibits significant changes in fluorescence anisotropy only in the presence of the guanidino substrate and the so-called "dead-end complex" containing arginine + MgADP. Several compounds structurally similar to arginine, e.g., ornithine do not interact with arginine kinase, suggesting a narrow specificity for substrate binding. The most suitable description of the decay of the fluorescence of arginine kinase derivatized with 5-[(((acetyl)-amino)ethyl)amino]naphthalene-1-sulfonate (AEDANS-AK), from among discrete and distributed models, is a triple exponential discrete decay. The presence of the dead-end complex only marginally increases the rate of decay, but significantly shifts the magnitude of the preexponentials (amplitudes) between the two major decay components. One interpretation of these results is that multiple conformational isomers may occur, in which the relative concentrations are dependent upon the presence of the dead-end complex. Measurement of the time-dependent anisotropy decay of AEDANS-AK reveals a two-term decay law with rotational correlation times of 0.88 and 15.2 ns. The slower component is close to the theoretical value of 16.7 ns for an isotropic rotator of the molecular mass of arginine kinase. This finding suggests that the overall conformation of arginine kinase may differ considerably from the prolate ellipsoidal subunits of the functionally analogous creatine kinase.

The Bacillus subtilis clpC operon encodes DNA repair and competence proteins

ClpC of Bacillus subtilis, controlling competence gene expression and survival under stress conditions, is encoded by the fourth gene of a six-gene operon. The product of orf1 contains a potential helix-turn-helix motif, but shows no significant similarities with known protein sequences. The second and third genes encode proteins with similarities to zinc-finger proteins (orf2) and arginine kinases (orf3), respectively. The product of orf5 contains a zinc-finger motif and an ATP-binding domain, and is highly similar to the product of the Escherichia coli sms gene. A strain bearing a disruption of orf5 showed increased sensitivity to the alkylating agent methyl methanesulfonate. Furthermore, this mutant strain displayed decreased capacity for genetic recombination as measured by transformation experiments. The last open reading frame, orf6, encodes a protein with limited similarity in its C-terminal part to the B. subtilis comEA gene product and to the UvrC DNA repair excinuclease. Inactivation of orf5 resulted in strongly diminished transformation with all types of DNA. Mutations affecting either orf5 or orf6 resulted in strains with decreased resistance to UV-irradiation in the stationary phase, indicating that these proteins play a role in the development of a non-specific stationary-phase resistance to UV-irradiation. Moreover, these results suggest an involvement of both proteins in transformation and presumably in DNA repair.

Conformational changes of arginine kinase induced by photochemical release of nucleotides from caged nucleotides--an infrared difference-spectroscopy investigation

The conformations of arginine kinase (AK) in AK x Mg x ADP, AK x Mg x ATP, AK x Mg x ADP x NO3-, AK x Mg x ADP x Arg and AK x Mg x ADP x NO3- x Arg complexes were investigated by measuring their reaction-induced infrared difference spectra (RIDS). The photochemical release of ATP from ATP[Et(PhNO2)] and of ADP from ADP[Et(PhNO2)] produced distinct RIDS of AK complexes, suggesting that binding of ADP and ATP promoted different structural alterations of the enzyme active-site. Small infrared changes in the amide-I region were observed, indicating that about 5-10 amino acid residues were involved in the nucleotide-binding site. These infrared changes were due to the structural alteration of the peptide backbone caused by the nucleotide-binding and to the coupling effects between the nucleotide-binding site and the other substrate (Arg or NO3-)-binding site. ATP binding to AK (as well as ADP-binding to AK in the presence of NO3-) induced protonation of a carboxylate group of Asp or Glu, as evidenced by the appearance of the 1733-cm(-1) band, which was not observed with the AK x Mg x ADP, AK x Mg x ADP x Arg and AK x Mg x ADP x NO3- x Arg complexes. The RIDS of the AK x Mg x ADP x NO3- x Arg complex showed new infrared bands at 1622 cm(-1) (negative) and at 1613 cm(-1) (positive), which were not seen in the RIDS of other complexes (without NO3- or/and Arg). In the transition-state-analog complex of AK, no protonation of the carboxylate residue (Asp or Glu) was observed, and the binding site of NO3- or the gamma-phosphate group of nucleotide was altered.

Expression, purification from inclusion bodies, and crystal characterization of a transition state analog complex of arginine kinase: a model for studying phosphagen kinases

Phosphagen kinases catalyze the reversible transfer of a phosphoryl group between guanidino phosphate compounds and ADP, thereby regenerating ATP during bursts of cellular activity. Large quantities of highly pure arginine kinase (EC 2.7.3.3), the phosphagen kinase present in arthropods, have been isolated from E. coli, into which the cDNA for the horseshoe crab enzyme had been cloned. Purification involves size exclusion and anion exchange chromatographies applied in the denatured and refolded states. The recombinant enzyme has been crystallized as a transition state analog complex. Near complete native diffraction data have been collected to 1.86 A resolution. Substitution of a recombinant source for a natural one, improvement in the purification, and data collection at cryo temperatures have all yielded significant improvements in diffraction.

Expression of horseshoe crab arginine kinase in Escherichia coli and site-directed mutations of the reactive cysteine peptide

Arginine kinase (AK) from the horseshoe crab Limulus polyphemus was expressed in Escherichia coli. The bulk of expressed protein resided in insoluble inclusion bodies. However, approximately 3 mg enzyme protein/l culture was present as active soluble AK. The AK-containing expression vector construct was subjected to site-directed mutagenesis via a polymerase chain reaction-based megaprimer protocol. The AK reactive cysteine peptide was engineered so that it was identical to the corresponding peptide sequence of creatine kinase, another member of the guanidino kinase enzyme family. The resulting expressed protein had a considerably reduced specific activity but was still specific for arginine/arginine phosphate. No catalytic activity was observed with other guanidine substrates (creatine, glycocyamine, taurocyamine, lombricine). The reactive cysteine peptide, characteristic of all guanidino kinases, very likely plays a minimal role in determining guanidine specificity.

Isolation and sequence analysis of the gene for arginine kinase from the chelicerate arthropod, Limulus polyphemus: insights into catalytically important residues

The gene for arginine kinase (AK; EC 2.7.3.3) from the horseshoe crab, Limulus polyphemus, was cloned and the complete cDNA sequence was determined. An open reading frame with 1071 nucleotides was detected that encodes a 357 amino-acid protein with a calculated M(r) of 40,238. The coding transcript is flanked by 13 and 512 nucleotides of 5' and 3' untranslated regions, respectively. The deduced amino-acid sequence of Limulus AK displays extensive similarity to other arginine kinases, vertebrate and invertebrate creatine kinases (CK) and a glycocyamine kinase (GK). Consensus AK and consensus CK sequences, as well as a GK sequence, were compared to CK peptide regions containing residues presumed to be important in catalysis and/or located in close proximity to the active site. Our comparisons revealed some inconsistencies with hypothesized roles of particular residues in catalytic function.

Lobster enolase crystallized by serendipity

An unknown protein crystallized from a lobster muscle preparation in which arginine kinase was the majority component. It was identified as enolase by peptide sequencing and activity testing, and a SIRAS electron density map showed its three-dimensional structure to be very similar to that of yeast enolase.

Sequence homology and structure predictions of the creatine kinase isoenzymes

Comparisons of the protein sequences and gene structures of the known creatine kinase isoenzymes and other guanidino kinases revealed high homology and were used to determine the evolutionary relationships of the various guanidino kinases. A 'CK framework' is defined, consisting of the most conserved sequence blocks, and 'diagnostic boxes' are identified which are characteristic for anyone creatine kinase isoenzyme (e.g. for vertebrate B-CK) and which may serve to distinguish this isoenzyme from all others (e.g. from M-CKs and Mi-CKs). Comparison of the guanidino kinases by near-UV and far-UV circular dichroism further indicates pronounced conservation of secondary structure as well as of aromatic amino acids that are involved in catalysis.