Functional analysis of the Cucumber mosaic virus 2b protein: Pathogenicity and nuclear localization

Yongzeng Wang, Tzvi Tzfira, Victor Gaba, Vitaly Citovsky, Peter Palukaitis, Amit Gal-On

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


The 2b protein encoded by Cucumber mosaic virus (CMV) has been shown to be a silencing suppressor and pathogenicity determinant in solanaceous hosts, but a movement determinant in cucumber. In addition, synergistic interactions between CMV and Zucchini yellow mosaic virus (ZYMV) have been described in several cucurbit species. Here, it was shown that deletion of the 2b gene from CMV prevented extensive systemic movement of the virus in zucchini squash, which could not be complemented by co-infection with ZYMV. Thus, ZYMV expressing a silencing suppressor with a different target could not complement the CMV 2b-specific movement function. Expression of the 2b protein from an attenuated ZYMV vector resulted in a synergistic response, largely restoring infection symptoms of wild-type ZYMV in several cucurbit species. Deletion or alteration of either of two nuclear localization signals (NLSs) did not affect nuclear localization in two assays, but did affect pathogenicity in several cucurbit species, whilst deletion of both NLSs led to loss of nuclear localization. The 2b protein interacted with an Arabidopsis thaliana karyopherin α protein (AtKAPα) in the yeast two-hybrid system, as did each of the two single NLS-deletion mutants. However, 2b protein containing a deletion of both NLSs was unable to interact with AtKAPα. These data suggest that the 2b protein localizes to the nucleus by using the karyopherin α-mediated system, but demonstrate that nuclear localization was insufficient for enhancement of the 2b-mediated pathogenic response in cucurbit hosts. Thus, the sequences corresponding to the two NLSs must have another role leading to pathogenicity enhancement.

Original languageEnglish
Pages (from-to)3135-3147
Number of pages13
JournalJournal of General Virology
Issue number10
StatePublished - 1 Oct 2004
Externally publishedYes

ASJC Scopus subject areas

  • Virology


Dive into the research topics of 'Functional analysis of the Cucumber mosaic virus 2b protein: Pathogenicity and nuclear localization'. Together they form a unique fingerprint.

Cite this