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ENF Peptides HPFP: Recent Advances in Insects and Other Arthropods Vol. 1 173 Family Species Abbreviation Peptide sequence Accession No. 1 6 11 16 21 Noctuidae Pseudaletia separata GBP ENFSGGCVAGYMRTPDGRCKPTFYQ P22800 Spodoptera exigua PP1 ENFAGGCTPGYQRTADGRCKATF P30255 PP2 ENFAGGCTPGYQRTADGRCKPTF P30256 PP3 ENFVGGCTPGYQRTADGRCKPTF P30257 Spodoptera litura GBP ENFAAGCATGYQRTADGRCKPTF BAA34953 Spodoptera eridania CAP23 ENFAVGCTPGYQRTADGRCKPTF P56683 Spodoptera frugiperda ENFAAGCATGYQRTADGRCKPTFG (DY774233) Trichoplusia ni PP1 ENFSGGCLAGYMRTADGRCKPTFG AAB26336 PP2 ENFSGGCLAGYMRTADGRCKPTF AAB26337 Mamestra brassicae GBP ENFAGGCLTGFMRTPDGRCKPTF BAA34952 Heliothis virescens PP1 ENFSGGCIPGYMRTADGRCKPTY P30251 PP2 ENFAGGCIPGYMRTADGRCKPTY P30252 Pseudoplusia Includens PSP1 ENFNGGCLAGYMRTADGRCKPTF O61704 Striacosta albicosta ENFKGACLTGFMRTPDGRCKPTF (EZ580795) Sphingidae Manduca sexta PP1 ENFAGGCATGYLRTADGRCKPTF P30253 PP2 ENFAGGCATGFLRTADGRCKPTF P30254 Theretra japonica PP ENFAGGCATGFMRTADGRCKPTF AB511035 Neogurelca himachala sangaica PP ENFAGGCATGFMRTADGRCKPTFG AB511034 Saturniidae Antheraea Yamamai PP ENFAGGCATGFMRTADGRCKPTF 1V28_A Antheraea assama ENFAGGCATGFMRTADGRCKPTFG (FG213039) Samia cynthia pryeri PP ENFAGGCATGFMRTADGRCKPTFG AB511033 Samia cynthia ricini ENFAGGCATGFMRTADGRCKPTFG (DC870385) Bombycidae Bombyx mori PP ENFVGGCATGFKRTADGRCKPTF BAB69463 Tortricidae Choristoneura fumiferana ENFKAACATGYGRTPDGRCKPTF (FC993021) Figure 1: Sequence alignment of insect ENF peptides and mouse EGF. For insects from which the mature ENF peptide has not yet been purified biochemically, the ENF peptide sequences were deduced from their cDNA sequences. For mouse EGF, only the C-terminal portion is depicted. Amino acids that are conserved in all or in more than half of the ENF peptides are highlighted in pink and orange, respectively. Two cysteine residues that form an intramolecular disulfide bond in the ENF peptides and EGF are boxed. Formation of the disulfide bond is also indicated. Accession numbers in parentheses are those of the EST sequences. 2. STRUCTURE 31 41 51 mouse EGF -DSYTCNCVIGY--SGD-RCQTRDLRWWELR P01132 All the ENF peptides identified so far are consisted of [23, 25] amino acids (Fig. 1). The primary structures of these peptides revealed 70 to 100 % sequence identity to one another. All of them contained two conserved cysteine residues (Cys 7 and Cys 19 ), which form an intramolecular disulfide bond and are essential for the peptide-specific biological activity [2-3, 7-8, 25]. Several mutational analysis studies revealed that, besides the two cysteine residues, the presence of the conserved Glu 1 , Phe 3 , Gly 5 , Gly 6 , Arg 13 , Asp 16 , and Phe 23 residues were important for their biological activities [8, 25-29]. Solution structures of four ENF peptides (i.e., P. separata GBP, P. includens PSP1, M. sexta PP1, and B. mori PP) were analyzed by NMR [30-33]. The calculated tertiary structures of all four of them were found to be very similar: they all possessed a structural core that was stabilized by the disulfide bond and a short anti-parallel -sheet and contained less ordered N- and C-termini (Fig. 2). These NMR analyses also showed that the structure of the core region shared similarity with that of the C-terminal region of the vertebrate epidermal growth factor (EGF) (Fig. 2), while they showed only weak sequence similarities (Fig. 1) [14, 30-33]. 3. GENE AND mRNA EXPRESSION A single ENF peptide gene was isolated from P. separata, M. brassicae, B. mori, S. cynthia pryeri, T. japonica, and N. himachala sangaica [13, 15, 19]. B. mori genome project [34] revealed that this moth has at least two homologous genes [11].
174 HPFP: Recent Advances in Insects and Other Arthropods Vol. 1 Manabu Kamimura C Figure 2: Comparison of three-dimensional structures of P. separata GBP and mouse EGF. Ribbon diagrams of GBP (left) and EGF (right) were generated using the atomic coordinates obtained from the PDB (entry sets 1BQF and 1EPG, respectively) [10]. The ENF peptide gene is expressed in many stages and tissues of moths. Transcripts of multiple sizes were detected during the embryogenesis of B. mori and M. brassicae [15, 18]. The mRNAs were not detected immediately following the oviposition, but were detected within the next 24 h, indicating that their origins were not maternal but zygotic. The M. brassicae GBP mRNA is specifically expressed in the suboesophageal body in the embryo under the control of a HOX transcriptional factor, Deformed [15, 35]. In M. sexta eggs, expression of the PP2 mRNA was enhanced by parasitization of the parasitoid wasp Trichogramma evanescens [36]. In the larval stage, the ENF peptide mRNAs were expressed in the fat body, hemocytes, central nervous system, epidermis, muscle, wing disc, and gonads (ovary and testis), and among these tissues their expressions, in general, were predominant in the fat body [12, 16-18, 37]. In contrast, these mRNAs were detected in small amounts in the silk gland, midgut or Malpighian tubules. While a 0.6-0.8 kb ENF peptide mRNA is predominantly expressed in many tissues, longer transcripts of sizes >2 kb were strongly expressed in the central nervous systems of P. separata and P. includens [13, 16]. In B. mori, the expression level of PP mRNA changed during the last larval instar under the control of juvenile hormone and molting hormone ecdysone [18]. In the P. separata larvae, expression of the GBP mRNA in the central nervous system was enhanced by parasitization of the parasitoid wasp A. kariyai [38]. Recently, it has been shown that a 1.5 kb embryonic PP mRNA of B. mori and a 2.5 kb larval GBP mRNA of P. separata are tricistronic mRNAs that encode not only the ENF peptide precursor but also two cytokine precursor-like proteins [19]. Orthologous tricistronic ENF peptide mRNAs were found in M. brassicae, S. cynthia pryeri, T. japonica, and N. himachala sangaica. 4. PROTEIN EXPRESSION, ACTIVATION, AND INACTIVATION C The ENF peptide is translated as an inactive larger precursor, consisting of 120 to 150 amino acids, and the bioactive ENF peptide is located at the C-terminal end of the precursor (Fig. 3A). This precursor protein (preproprotein) has a signal peptide containing a number of hydrophobic residues at the N-terminus end and is secreted out of the cells. The secreted protein is still an inactive precursor (proprotein) and is subsequently cleaved to form the active peptide after receiving special stimuli, such as bleeding and microorganism infection [17-18, 39]. Serine proteases, which are yet to be identified, are presumably responsible for this cleavage [17, 39]. For example, following an infection of B. mori by a microorganism, a cellular component of the microorganism, such as the peptidoglycan of bacteria or -1, 3-glucan of fungi, stimulates hemocytes to generate reactive oxygen species (ROS) (see for detail <strong>chapter</strong> number 8), and the N N
Page 2 and 3: Hemolymph Proteins and Functional P
Page 4 and 5: CONTENTS Foreword i Preface ii List
Page 6 and 7: ii PREFACE The aim of this eBook
Page 8 and 9: iv Giancarlo Lopez-Martinez Departm
Page 12 and 13: Hemolymph Lipoproteins: Role in Ins
Page 14 and 15: Adipokinetic Hormones and Their Rol
Page 16 and 17: 32 Hemolymph Proteins and Functiona
Page 18 and 19: 34 HPFP: Recent Advances in Insects
Page 20 and 21: Immune Response of Insects and Crus
Page 22 and 23: 78 Hemolymph Proteins and Functiona
Page 24 and 25: 80 HPFP: Recent Advances in Insects
Page 26 and 27: Structures and Functions of Insect
Page 30 and 31: Neurohormones and Second Messengers
Page 32 and 33: Role of Conventional and Unconventi
Page 36 and 37: Insulin-Related Peptides in Insects

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