Tomato yellow leaf curl virus (TYLCV) capsid protein (CP) subunit interactions: implications for viral assembly.

Tomato yellow leaf curl virus (TYLCV) capsid protein (CP) forms the capsule that encapsidates the viral genomic ssDNA. We have analyzed the homotypic interaction capacity of full-length and mutated CP. We found that full-length CP interacts with itself. Truncation of the protein from the C-terminal led to diminution of the self-interaction process. Also, the N-terminal region of the CP seemed to be necessary for the interaction. As the two deletion mutants interacted successfully with the wildtype protein, while they failed to self-interact, we suggest that the N-terminal amino acids interact with amino acids of the C-terminal region. Changes in CP homotypic interaction capacity were detected when mutations in the middle portion of the protein were introduced.