Sergei Kushnir
Genome Stability
VIB Department of Plant Systems Biology, UGent

PhD: Inst. of Botany, Kiev, USSR, '83-'89 Postdoctoral Fellow at the Univ. of Ghent, Ghent, Belgium, '91-'98 VIB Expert Scientisct since 2009

e-mail phone +32 9 331 38 90 ADDRESS

Current team members
Expert: Sergei Kouchnir
Postdoctoral scientist: Elena Babiychuk

Keywords
ADP-ribosylation – PARP – abiotic stress – DNA damage response – plastid biogenesis – RNA editing – nucleo-cytoplasmic interactions

Science
The modification of proteins by ADP-ribosylation is an ancient mechanism to control cell cycle progression; DNA damage response and many other processes.  It is catalyzed by the several classes of NAD+-metabolizing enzymes, among which poly(ADP-ribose) polymerase 1 (PARP1) in animals is the most known. The poly(ADP-ribose) glycohydrolase (PARG); ADP-ribose hydrolase and pyrophosphatase erase ADP-ribosylation.
The presence of the specific NAD+-binding amino acid signature suggests that Arabidopsis genome contains genes for twelve proteins capable of ADP-ribosylation and seven enzymes involved in the reversal of the modification. Plant PARP-like protein CEO/RCD protects yeast cells from drug-induced death and, in plants, is a key regulator of responses to abiotic stress. Under stress conditions, improvements in the energy homeostasis can be achieved by the lowering of the APP and ZAP plant PARP gene activities, hence such adjustments to the plant energy metabolism are successfully exploited in breeding of crop species for the new varieties with a better stress tolerance (Babiychuk et al., 2004).       
Reduced carbon and oxygen to burn it are predominantly provided by the photosynthesis, which makes it the most important process required to maintain animal life on the planet. In higher plants, it occurs in plastids. Whilst photosynthesis is a key process for the growth and development of plants themselves, plastids do much more for the plant cell. Resolving old mysteries is one approach to gain a comprehensive understanding of the role of plastids in the plant life cycle. In the middle of the twentieth century, a German geneticist Michaelis proposed that an important role for plastids is a fixation of the post-zygotic interspecies isolation barriers through a mechanism that is known as nucleo-cytoplasmic incompatibility. The molecular details of the mechanism remained enigmatic until the process of RNA editing was found to be responsible for the incompatibilities reactions between the nucleus and plastids of different species in Solanaceae (Schmitz-linneweber et al., 2005; Tillich et al., 2006).  Another approach to better our knowledge of plastid biology is to search for processes and molecules outside of plastids that nevertheless impact on photosynthesis or plastid biogenesis. Such experimentation confirmed the functional connections between plastids and mitochondria (Kushnir et al., 2001); and revealed a novel role for sterols in plastid biogenesis (Babiychuk et al., 2008).

Selected Patents

Babiychuk E, Kouchnir S, De Block M
Methods and means to modulate programmed cell death in eukaryotic cells
United States Patent US2004/0128704 A1, 2004

Babiychuk E, Bouvier-Navé P, Compagnon V, Suzuki M, Muranaka T, Van Montagu M, Kouchnir S, Schaller H
Allelic mutant series reveal distinct functions for Arabidopsis cycloartenol synthase 1 in cell viability and plastid biogenesis
P NATL ACAD SCI USA 105, 3163-8, 2008



Tillich M, Poltnigg P, Kouchnir S, Schmitz-Linneweber C
Maintenance of plastid RNA editing activities independently of their target sites
EMBO REP 7, 308-13, 2006



Schmitz-Linneweber C, Kouchnir S, Babiychuk E, Poltnigg P, Herrmann g, Maier m
Pigment Deficiency in Nightshade/Tobacco Cybrids Is Caused by the Failure to Edit the Plastid ATPase {alpha}-Subunit mRNA
PLANT CELL 17, 1815-1828, 2005



Kouchnir S, Babiychuk E, Storojenko S, Davey M, Papenbrock J, De Rycke R, Engler G, Stephan w, Lange H, Kispal G, Lill R, Van Montagu M
A mutation of the mitochondrial ABC transporter Sta1 leads to dwarfism and chlorosis in the Arabidopsis mutant starik
PLANT CELL 13, 89- 100, 2001

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