Uncovering the biological relevance of the replication-associated protein splicing during viral replication in geminiviruses and other CRESS viruses

Due to their limited protein-coding capacity, viruses have evolved sophisticated mechanisms to hijack the host molecular machinery for their own benefit; among these strategies, splicing of the viral transcripts allows them to increase their transcriptome and proteome diversity, and has been described in several virus families, including plant DNA viruses, such as geminiviruses.

Geminiviruses, which cause devastating problems for the agriculture worldwide, belong to the circular, replication-associated protein (Rep)-encoding (CRESS) viruses, a phylum infecting organisms from all three domains of life and potentially sharing analogous mechanisms for genome replication.

Importantly, Rep is the only protein required for viral replication, and is structurally conserved across CRESS viruses.

Splicing of Rep transcripts has been anecdotally reported in circoviruses and a few minor genera of geminiviruses, with some splicing events required for a full infectivity.

On the other hand, unpublished work in the host group has uncovered that i) Rep from different begomoviruses, the major genus within the Geminiviridae family, associate with the plant splicing machinery; and ii) tomato yellow leaf curl virus (TYLCV) Rep transcripts are spliced during the infection, giving rise to at least five unknown Rep protein isoforms, lacking either the oligomerization domain or part of the N-terminal DNA binding domain.

We propose to uncover the importance of Rep splicing in TYLCV and to establish its relevance during the viral replication, by characterizing Rep spliced variants interactome and functions.

We will also analyze the conservation of Rep splicing landscape in different geminiviruses and CRESS viruses, potentially outlining an unknown layer in the regulation of the replication of these cross-kingdom infecting viruses.