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Title: SEQUENCING AND MOLECULAR CHARACTERIZATION OF A VITELLOGENIN CDNA FROM THE GLASSY-WINGED SHARPSHOOTER, HOMALODISCA VITRIPENNIS

Author
item Hunter, Wayne
item Boykin, Laura
item Hunnicutt, Laura

Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2007
Publication Date: 9/30/2007
Citation: Hunter, W.B., Boykin, L.M., Hunnicutt, L.E. 2007. Sequencing and molecular characterization of a vitellogenin cdna from the Glassy-winged sharpshooter, Homalodisca vitripennis. Archives of Insect Biochemistry and Physiology.

Interpretive Summary: Insects, such as the glassy-winged sharpshooter, GWSS, provision their eggs with proteins classified as vitellogenins. The vitellogenin of the GWSS, was sequenced and compared to other known egg proteins. Genetic and protein sequence comparison demonstrated a significant relationship of the GWSS vitellogenin to that of another Hemipteran species, the cicada. Understanding how the GWSS eggs develop, and which proteins are critical for the nymphs to develop may lead to new strategies to manage these serious economic pests.

Technical Abstract: The complete cDNA for vitellogenin (Vg) of the glassy-winged sharpshooter, Homalodisca coagulata (Say) (Hemiptera: Cicadellidae), was cloned and sequenced. The coding region consists of 5823 nucleotides (nt) flanked by untranslated regions (UTRs) of 91 nt on the 5'-proximal end and 60 nt on the 3'-proxminal end, excluding the poly(A) tail. Conceptual translation of the cDNA yielded a single, long open reading frame (ORF) comprised of 1890 amino acids, including 16 residues which are thought to encode a signal peptide. Alignment of H. coagulata Vg (Hc-Vg) with 14 other insect Vgs revealed several conserved motifs including two discontinuous serine-rich stretches joined by a short region (35 nt) which contains a paired-basic motif (RFAR) putatively involved in cleavage site recognition by subtilisin-like proprotein convertases. Additional regions of conservation were noted near the C-terminus of the protein, including the G(L/I) (C/A)G and DGXR motifs which occur with only slight modification. A maximum likelihood phylogeny was produced using 35 vitellogenin amino acid sequences, less the putative signal peptide, derived from over 20 distinct insect species including H. coagulata. The resultant phylogenetic reconstruction was largely concordant with currently accepted character-based phylogenies with the Hemiptera forming a single cluster. Of those included in the analysis, Hc-Vg was most closely related to the predicted Vg amino acid sequence from the cicada Graptopsaltria nigrofuscata, another Hemipteran species.