tailieunhanh - Báo cáo khoa học: Tritium planigraphy comparative structural study of tobacco mosaic virus and its mutant with altered host specificity

Spatial organizationofwild-type (strainU1) tobaccomosaic virus (TMV) and of the temperature-sensitive TMV ts21–66 mutant was compared by tritium planigraphy. The ts21–66 mutant contains two substitutions in the coat protein (Ile21fiThr and Asp66fiGly) and, in contrast withU1, induces a hypersensitive response (formation of necroses) on the leaves of plants bearing a host resistance geneN¢(for example Nicotiana sylvestris); TMV U1 induces systemic infection (mosaic) on the leaves of such plants. Tritium dis-tribution along the coat protein (CP) polypeptide chain was determined after labelling of bothisolated CP preparations and intact virions. . | Eur. J. Biochem. 270 3300-3308 2003 FEBS 2003 doi Tritium planigraphy comparative structural study of tobacco mosaic virus and its mutant with altered host specificity Eugenie N. Dobrov1 Gennadii A. Badun2 Elena V. Lukashina2 Nataliya V. Fedorova1 Alexander L. Ksenofontov1 Vladimir M. Fedoseev2 and Ludmila A. Baratova1 1 . Belozersky Institute of Physico-Chemical Biology and department of Chemistry Moscow State University Russia Spatial organization of wild-type strain U1 tobacco mosaic virus TMV and of the temperature-sensitive TMV ts21-66 mutant was compared by tritium planigraphy. The ts21-66 mutant contains two substitutions in the coat protein Ile21 fi Thr and Asp66 fi Gly and in contrast with Ul induces a hypersensitive response formation of necroses on the leaves of plants bearing a host resistance gene N for example Nicotiana syliestris TMV U1 induces systemic infection mosaic on the leaves of such plants. Tritium distribution along the coat protein CP polypeptide chain was determined after labelling of both isolatd CP preparaiions and intact virions. In the case of the isolated low-order 3-4S CP aggregates no reliable differences in tritium distribution between U1 and ts21-66 were found. But in labelling of the intact virions a significant difference between the wild-type and mutant CPs was observed the N-terminal region of ts21-66 CP incorporated half the amount of tritium than the corresponding region of U1 CP. This means that in U1 virions the CP N-terminal segment is more exposed on the virion surface than in ts21-66 virions. The possibility of direct participation of the N-terminal tail of U1 CP subunits in the process of the N hypersensitive response suppression is discussed. Keywords coat protein hypersensitive response tobacco mosaic virus tritium planigraphy. Systems in which defined modifications in a pathogen structure cause specific changes in a host response are highly useful in studies of molecular .

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