Vitaly Citovsky was born in Moscow, Russia. He attended the Hebrew University in Jerusalem, Israel, to obtain B. S., M. S., and Ph.D. degrees in biology and biochemistry in 1981, 1982, and 1987, respectively. For his doctoral research with Abraham Loyter, Citovsky investigated interactions between enveloped animal viruses and host cell membranes. He then joined Patricia Zambryski’s group at the University of California-Berkeley, where he conducted post-doctoral work on cell-to-cell movement of plant viruses and the mechanisms of plant cell transformation by Agrobacterium tumefaciens. In 1993, Citovsky was appointed to the faculty in the Department of Biochemistry and Cell Biology at the State University of New York-Stony Brook, where he was promoted to associate professor with tenure in 1999 and advanced to the rank of professor in 2003.
Citovsky has made numerous seminal contributions to the field of plant-pathogen interactions by studying basic biology of cell-to-cell transport of plant viruses and the Agrobacterium-mediated genetic transformation of cells. In his early studies of plant viruses, Citovsky examined mechanisms that facilitate macromolecular transport between plant cells and discovered paradigm shifting properties. Citovsky was the first to describe two major properties of plant viral cell-to-cell movement proteins: formation of cell-to-cell transport complexes with nucleic acids, and host control of movement protein function by phosphorylation. His now-classic finding that Tobacco mosaic virus cell-to-cell movement is mediated via transit of an RNA protein complex rather than of virions set the stage for an explosive series of investigations that altered concepts of virus trafficking in plants. Citovsky also identified novel host factors involved in virus movement, for instance, those that control callose sphincters that regulate permeability of plasmodesmata. Subsequently, he discovered a host protein complex that controls plasmodesmal callose in the vascular system and another regulator that controls plasmodesmal callose in nonvascular tissues. These and other results strongly supported Citovsky’s concept that plant viruses commandeer diverse host components that are normally involved in intra- and intercellular nucleic acid trafficking during development.
Citovsky’s studies with Agrobacterium have provided new models to elucidate cellular events and host defense subjugation strategies involved in the genetic transformation of cells. He has described functions for bacterial effector proteins exported into the host cell, specifically virulence (Vir) factors for nuclear import and packaging of transfer DNA (T-DNA) complexes, proteasomal uncoating of these complexes, and protection of VirF from host proteolytic activities. In addition to specifying the bacterial components, Citovsky also identified and characterized the plant factors involved in the major steps of genetic transformation, including those for nuclear import of the T-DNA, chromatin targeting, and proteasomal uncoating and integration of T-DNA. These investigations uncovered and characterized critical steps in the Agrobacterium infection strategy, in which it exports into the host cell bacterial effectors that mimic and augment the cellular functions of host factors required for transformation. His studies have also elaborated a strategy that pathogens use in the “arms race” with their plant hosts—subversion, rather than suppression, of the host defense, in which Agrobacterium utilizes defense-related transcription factors and F-box proteins of the host plant for critical steps of infection. Finally, Citovsky’s research has demonstrated the general nature of the genetic transformation principle by showing that Agrobacterium can transform frog oocytes and human cells. Collectively, Citovsky’s original findings have exerted an enormous impact on our collective conceptual understanding of the molecular mechanisms leading to gene transfer and transformation.
Citovsky’s contributions also extend to areas beyond plant-pathogen interactions. For instance, his investigations into the composition and biochemical activities of a plant histone demethylase gene repressor complex revealed that plants utilize a novel histone deubiquitinase and differ from animal cells in this aspect of regulating protein turnover. Citovsky’s innovations also produced new molecular tools for plant research. For example, he recently pioneered the reconstitution of a bacterial multigene biochemical pathway for autoluminescence within plant chloroplasts to create a valuable tool for cell biology research. Other useful tools include a vector system for one-step detection of functional nuclear localization signals, a series of vectors for transient and stable single- and multigene expression in plants, vectors for bimolecular fluorescence complementation assays for protein-protein interactions in living plant cells, and a high-throughput methodology, termed fluorescent tagging of full-length proteins (FTFLP), to analyze expression patterns and subcellular localization of Arabidopsis gene products in planta.
Citovsky is a member of Faculty of 1000 Biology and serves as an associate editor for Frontiers in Plant-Microbe Interactions and monitoring editor for Plant Physiology, and he is on the editorial boards of several journals, including Virology and Molecular Plant Pathology. He has also organized and edited various special issues in different journals and frequently organizes international symposia. Citovsky serves regularly on review panels of various national and international funding agencies, such as NSF, NIH, and BARD. As an important component of his service, Citovsky has proven to be a powerful advocate for fundamental plant pathology research and for activities of the plant science community.
Citovsky has mentored more than 20 post-doctoral fellows and numerous undergraduates and has an impressive federal funding track record totaling about 12.5 million dollars. His prolific publication list totals more than 170 papers, of which many have appeared in the most prestigious scientific journals (e.g., Cell, Cell Host Microbe, Nature, Nature Cell Biology, Science, Science Signaling, EMBO Journal, and PNAS) that cater to cutting-edge science of interest to a broad spectrum of readers from all scientific disciplines. Citovsky’s findings have contributed enormously to developing concepts about the infection processes of bacteria and viruses and their cell biology, as well as providing important clues about developmental processes in general. He clearly has demonstrated continued research excellence and leadership to significantly advance our collective understanding of molecular host-pathogen interactions. In conclusion, Citovsky has amply demonstrated research excellence in molecular plant-microbe interactions and has proven that he is an exceptional scientist who typifies the spirit of the Noel T. Keen Award for Research Excellence in Molecular Plant Pathology.
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