Research group Lozano-Durán
Dr. Rosa Lozano-Durán
ZMBP, Plant Biochemistry
5th floor, room 5P22
Auf der Morgenstelle 32
Tel +49-7071/ 29 78095
Fax + 49 7071 29 5226
Exploring the functional diversification of the C4 proteins encoded by geminiviruses
Funder: DFG (TRR 356)
Abstract: The C4 protein encoded by geminiviruses is an essential pathogenicity determinant and the most divergent protein in this virus family. We have recently described that C4 from tomato yellow leaf curl virus (TYLCV) localizes in two distinct subcellular compartments, namely plasma membrane (PM)/plasmodesmata (PD) and chloroplasts. PM-localized C4 can suppress the cell-to-cell movement of RNA interference by targeting two plant receptor-like kinases at PD; chloroplast-localized C4 interferes with the downstream activation of defence, suppressing activation of salicylic acid (SA) biosynthesis upon pathogen perception, through its interaction with a thylakoid protein. Therefore, C4 from TYLCV plays a dual role in the suppression of plant defences, illustrating how subcellular compartmentalization of viral proteins can underlie multifunctionality. Although C4 is essential in all species analyzed to date, the properties and roles of most C4 proteins in this virus family remain to be determined. Among geminiviral proteins, C4 seems to be exceptional: while all other proteins are subjected to negative or purifying selection, C4 seems to be under positive selection; the other positional homologues in the geminiviral genome display common or mostly overlapping subcellular localizations, but C4 from different geminiviruses appears in distinct cellular compartments; and no common, general function has been described for C4 proteins so far. Taken together, these observations lead us to hypothesize that C4 is exploring its potential functional landscape, acquiring novel subcellular targets and interactors and giving rise to divergent properties and functions in different viral species. Further supporting this idea is the finding that replacement of the C4-coding sequence is sufficient to produce a quantitative increase in virulence, acquisition of independence from a satellite molecule, or breakdown of resistance. In this proposal, we intend to explore the diversity in the C4 proteins encoded by different geminivirus species, in terms of their subcellular localization, virulence functions, interactome, host targets, and developmental alterations caused by their expression in planta, and to gain insight into the molecular mechanisms underlying their role during the infection. We anticipate that relevant host processes/pathways/proteins might emerge as convergently targeted by different C4 proteins through independently evolved strategies.
Participating lab members: Hua Wei, Shaojun Pan.
Specific manipulation of the plant RNA splicing machinery by geminiviruses
Funder: DFG (CRC 1101)
Abstract: Due to their limited coding capacity, viruses have evolved efficient mechanisms to co-opt the host molecular machinery in order to enable their own replication and spread. One viral strategy to maximize the use of coding space is the alternative splicing of viral transcripts to increase transcriptome and proteome diversity. Studies in mammalian viruses have uncovered splicing as a key host process hijacked during the infection; however, while recent accumulating evidence indicates that the splicing landscape in plants is dramatically reshaped upon pathogen attack, the specific contribution of this layer of regulation to plant-virus interactions remains to be investigated. Geminiviruses are a family of plant DNA viruses causing devastating diseases in crops worldwide. We have recently found that i) the geminiviral replication-related protein physically associates with the plant splicing machinery; ii) geminiviral transcripts are spliced and give rise to new proteins, which can be detected during the infection; iii) splicing is required for geminiviral replication and systemic infection; and iv) the geminiviral infection drastically impacts the host splicing landscape. Therefore, splicing emerges as a central process at the interface between geminiviruses and their host plants. Here, we propose to investigate the biological significance of splicing during the geminiviral infection and the mechanisms underlying its co-option by geminiviruses, by using a combination of next-generation sequencing, molecular and cell biology, and reverse genetics. The results obtained in this project will further our understanding of geminivirus biology and plant-geminivirus interactions, and may pave the way for the development of new strategies to control the damaging diseases these pathogens cause.
Participating lab members: Delphine Pott, Man Gao.
Emerging multifactorial complexity at the geminivirus-host interface
Funder: European Research Council (ERC)
Abstract: Viruses manipulate their host cells to replicate and spread. This manipulation is based on the activity of virus-encoded proteins, limited due to restrictions in genome size imposed by the viral cycle. How the action of these few proteins results in the massive cell reprogramming observed during the infection remains enigmatic.
Geminiviruses are plant viruses causing diseases in crops worldwide. Recent results obtained in our lab using the geminivirus Tomato yellow mosaic virus (TYLCV) indicate that the proteome of this species, so far believed to encompass 6 proteins, is far more complex than anticipated: the TYLCV genome contains additional small open reading frames expressed during the infection and giving rise to new proteins, and viral transcripts are spliced and generate new protein variants. Therefore, the number of viral proteins exceeds double that previously accepted. In addition, we have found that this higher complexity is further increased by the association of viral proteins in an intricate network of intra-viral interactions, which enable novel protein localization and function, leading to an expansion of their interactome and functional spaces.
Our results imply that, to get a complete overview of the molecular and functional landscape of plant-geminivirus interactions, the strategies traditionally used, based on the analysis of a limited number of viral proteins in isolation, need to be revisited. Here, we propose to apply a combination of genomic, interactomic, and functional approaches to generate a comprehensive map of the virus/host cell intersection with unprecedented resolution. We will perform a comparative analysis of different geminivirus species, and translate these emerging concepts to independently evolved viral families. The conceptual and practical enlargement of the virus/host interface elucidated in this project has the potential to re-shape the theoretical framework and experimental approaches in the study of virus/host interactions.
Participating lab members: Yu Zhou, Zhihao Jiang, Ying Li.