Sergei Pletnev, Ph.D.
Dr. Pletnev's research focuses on structural studies of fluorescent proteins (FPs), a class of natural and bio-engineered proteins used as non-invasive fluorescent biomarkers and biosensors. The primary application of FPs is in vivo measurements of certain physical and chemical parameters and monitoring of various processes in living systems (cells, tissues or whole organisms). They could also be used to visualize almost every aspect of cancer in living animals—tumor cell mobility, invasion, metastasis and angiogenesis and enable a high-throughput screening of drug candidates. Dr. Pletnev's studies are aimed at improving characteristics of FPs important for their successful application.
My current research focuses on structural studies of fluorescent proteins (GFP-based, phytochromes and recently fluorogenic proteins), which are natural and bio-engineered proteins used as non-invasive fluorescent biomarkers, biosensors and optogenetic tools. FPs are used in a variety of applications to study organization and function of living systems. They make it possible to observe localization, movement, turnover and even “aging” (i.e., time passed from protein synthesis) of target proteins. Nucleic acids also can be labeled via RNA- or DNA-binding protein domains. FPs targeted to cell organelles by specific protein localization signals enable visualization of their morphology, fusion and fission, segregation during cell division, etc. FPs are essential tools for individual cell and tissue labeling to visualize morphology, location and movement (e.g., during embryonic development and tumorigenesis), mitotic stages and many other important cell characteristics.
Development of FP biomarkers consists of two alternating steps of optimization cycle – rational design and directed evolution. The whole process of FP optimization then consists of numerous repetitions of optimization cycle. Rational design comprises introduction of specific key mutations, while directed evolution is aimed at optimization of FP properties by random mutagenesis with a subsequent selection of the best variants that meet target criterions. The rational design stage heavily relies on structural information guidance. My work is aimed at structure-based improvement of physical and chemical characteristics of FPs important for their new and efficient application: spectral diversity, brightness, photo- and pH-stability, ion sensitivity, phototoxicity, photoswitchability, time-resolved properties, etc. I conduct this research in collaboration with two leading teams in the field of fluorescent proteins, one from Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences and another from Albert-Einstein College of Medicine.
Selected Key Publications
Locations of carbohydrate sites on alphavirus glycoproteins show that E1 forms an icosahedral scaffold..Cell. 105/1: 127-136, 2001. [ Journal Article ]
- Cell. 108/5: 717-725, 2002. [ Journal Article ]
- J Biol Chem. 284/46: 32028-39, 2009. [ Journal Article ]
Understanding blue-to-red conversion in monomeric fluorescent timers and hydrolytic degradation of their chromophores..J Am Chem Soc. 132/7: 2243-53, 2010. [ Journal Article ]
- Chem Biol. 22/11: 1540-1551, 2015. [ Journal Article ]
Dr. Pletnev did his graduate studies at Shubnikov Institute for Crystallography, Russian Academy of Sciences, under the supervision of Professor Emil Harutyunyan solving the structures of Tyrosine Phenol Lyase in apo- and holo- forms and in complex with quasi-substrate, elucidating the mechanism of this enzyme. As a part of his training, Dr. Pletnev spent 6 months at the lab of Guy Dodson at the University of York, UK, learning contemporary techniques for X-ray data collection using home and synchrotron radiation sources. After receiving his Ph.D. in late 1997, Dr. Pletnev joined the lab of Professor Michael Rossmann at Purdue University, where he learned molecular biology and structural virology. There, he participated in several challenging and exciting projects that revealed the structures of Sindbis and Dengue viruses. In 2001, Dr. Pletnev joined the Macromolecular Crystallography Laboratory of Dr. Alexander Wlodawer, where he worked on HIV integrase and human interleukins receptor-ligand complexes. He later moved to the group of Dr. Zbigniew Dauter, where he carries on an independent research on non-invasive biomarkers and optogenetic tools (GFP-based fluorescent proteins, phytochromes and recently fluorogenic proteins) that helps to better understand their mechanisms and improve their performance.