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Journal of General Virology
Kimalov, B., Dept. of Ornamental Horticulture, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Gal-On, A., Department of Virology, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Stav, R., Dept. of Ornamental Horticulture, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Belausov, E., Horticulture Institute, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Arazi, T., Dept. of Ornamental Horticulture, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Zucchini yellow mosaic virus (ZYMV) surface exposed coat protein (CP) N-terminal domain (Nt) is 43 aa long and contains an equal number of positively and negatively charged amino acid residues (CP-Nt net charge = 0). A ZYMV-AGII truncation mutant lacking the first 20 aa of its CP-Nt (AGII-CPΔ20; CP-Nt net charge = +2) was found to be systemically non-infectious even though AGII mutants harbouring larger CP-Nt deletions were previously demonstrated to be fully infectious. Nevertheless, AGII-CPΔ20 infectivity was restored by fusion to its CP-Nt two Asp residues or a negatively charged Myc peptide, both predicted to neutralize CP-Nt net positive charge. To evaluate further the significance of CP-Nt net charge for AGII infectivity, a series of CP-Nt net charge mutants was generated and analysed for systemic infectivity of squash plants. AGII-CpKKK harbouring a CP-Nt amino fusion of three Lys residues (CP-Nt net charge = +3) was not systemically infectious. Addition of up to four Asp residues to CP-Nt did not abolish virus infectivity, although certain mutants were genetically unstable and had delayed infectivity. Addition of five negatively charged residues abolished infectivity (AGII-CPDDDDD; CP-Nt net charge = -5) even though a recombinant CPDDDDD could assemble into potyviral-like particle in bacteria. Neutralization of CP-Nt net charge by fusing Asp or Lys residues recovered infectivity of AGII-CPKKK and AGII-CPDDDDD. GFP-tagging of these mutants has demonstrated that both viruses have defective cell-to-cell movement. Together, these findings suggest that maintenance of CP-Nt net charge and not primary sequence is essential for ZYMV infectivity. © 2004 SGM.
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Maintenance of coat protein N-terminal net charge and not primary sequence is essential for Zucchini yellow mosaic virus systemic infectivity
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Kimalov, B., Dept. of Ornamental Horticulture, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Gal-On, A., Department of Virology, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Stav, R., Dept. of Ornamental Horticulture, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Belausov, E., Horticulture Institute, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Arazi, T., Dept. of Ornamental Horticulture, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Maintenance of coat protein N-terminal net charge and not primary sequence is essential for Zucchini yellow mosaic virus systemic infectivity
Zucchini yellow mosaic virus (ZYMV) surface exposed coat protein (CP) N-terminal domain (Nt) is 43 aa long and contains an equal number of positively and negatively charged amino acid residues (CP-Nt net charge = 0). A ZYMV-AGII truncation mutant lacking the first 20 aa of its CP-Nt (AGII-CPΔ20; CP-Nt net charge = +2) was found to be systemically non-infectious even though AGII mutants harbouring larger CP-Nt deletions were previously demonstrated to be fully infectious. Nevertheless, AGII-CPΔ20 infectivity was restored by fusion to its CP-Nt two Asp residues or a negatively charged Myc peptide, both predicted to neutralize CP-Nt net positive charge. To evaluate further the significance of CP-Nt net charge for AGII infectivity, a series of CP-Nt net charge mutants was generated and analysed for systemic infectivity of squash plants. AGII-CpKKK harbouring a CP-Nt amino fusion of three Lys residues (CP-Nt net charge = +3) was not systemically infectious. Addition of up to four Asp residues to CP-Nt did not abolish virus infectivity, although certain mutants were genetically unstable and had delayed infectivity. Addition of five negatively charged residues abolished infectivity (AGII-CPDDDDD; CP-Nt net charge = -5) even though a recombinant CPDDDDD could assemble into potyviral-like particle in bacteria. Neutralization of CP-Nt net charge by fusing Asp or Lys residues recovered infectivity of AGII-CPKKK and AGII-CPDDDDD. GFP-tagging of these mutants has demonstrated that both viruses have defective cell-to-cell movement. Together, these findings suggest that maintenance of CP-Nt net charge and not primary sequence is essential for ZYMV infectivity. © 2004 SGM.
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