Structural Analysis of the Coat Protein of Cucumber Green Mottle Mosaic Virus

T. I. Odintsova^1*, E. N. Andreeva¹, V. A. Pukhal'skii¹, A. Kh. Musolyamov², and T. A. Egorov²

¹Vavilov Institute of General Genetics, Russian Academy of Sciences, ul. Gubkina 3, Moscow, 117809 Russia; fax: (095) 135-1289; E-mail: pukhalsk@vigg.ru

²Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, Moscow, 117984 Russia; fax: (095) 135-1405; E-mail: egorov@imb.imb.ac.ru

^* To whom correspondence should be addressed.

Received July 5, 1999; Revision received January 11, 2000

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Using reversed-phase high-performance liquid chromatography, two components of the coat protein of isolate No. 3 of the cucumber green mottle mosaic virus (CGMMV, cucumber strain), Cp1 (minor) and Cp2 (major), were isolated and characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). In the Cp2 mass spectrum, two polypeptides with M_r of 16,727.0 and 16,813.5 were detected. By Edman degradation in combination with mass spectrometry, the primary structure of the tryptic peptides of Cp2 comprising in total 150 amino acid residues was determined. Two amino acid substitutions, Val-56-->Ala-56 and Asp-64-->Ser-64, were revealed in Cp2, as compared to the watermelon strain of the virus. Cp1 was shown to consist of three polypeptides with M_r of 10,014.2, 10,224.9, and 10,355.9 corresponding to the N-terminal regions of Cp2 (positions 1-92, 1-94, and 1-95). The observed heterogeneity of the coat protein of CGMMV, cucumber strain, may be due to proteolysis during protein isolation.

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KEY WORDS: tobamoviruses, cucumber green mottle mosaic virus, coat protein, isolate No. 3, peptide mapping, mass spectrometry

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