Founded in 1975 as the all Union Research Institute of Applied Enzimology, currently, the Institute of Biotechnology is mainly involved in research and training in the fields of biotechnology and molecular biology, including research and development of recombinant biomedical proteins, genetic and molecular studies of restriction modification phenomenon, developing of viruses diagnostics, epigenetic study of small RNA, drug design and synthesis, bioinformatics.
Dalia Gritėnaitė, Linas Antoniukas, Agnė Valinčiūtė, Evaldas Čiplys, Raminta Jonikaitė, Rimantas Slibinskas, Mindaugas Juozapaitis (left to right, top to bottom)
Proteomic approach was applied a to study molecular processes leading to formation of insoluble and inactive aggregates of recombinant mumps virus hemagglutinin-neuraminidase (MuHN) and measles virus hemagglutinin (MeH) in yeast Saccharomyces cerevisiae cells.
Overexpression of cytoplasmic cell stress proteins Ssa1/2, Ssa4, Sse1, Hsc82, Hsp104, Sti1 and Sgt2 in response to MuHN and MeH synthesis indicated the presence of a stress response specific to accumulation of secretory protein precursors in the cytoplasm. Major cellular components of insoluble MuHN and MeH aggregates, directly interacting with recombinant viral proteins, appeared to be cytoplasmic heat shock proteins Ssa1/2p and Hsp26, the endoplasmic reticulum (ER) chaperone BiP/Kar2p was also identified. We may conclude the reason of inefficient virus surface glycoprotein expression in yeast lies on different protein maturation processes in mammalian and yeast cells, comprising translocation across the ER membrane and/or protein folding in the ER lumen. Now our lab is involved into the improvement of yeast expression systems for generation of active human virus surface glycoproteins.
2D gel electrophoresis of yeast proteins
Samples were taken from cells, expressing MuHN (central panel; B-H) or MeH (right panel; C-I) and from control cells, non-expressing these proteins (left panel; A-G). At the top (A-C) total protein lysates, in the middle (D-F) fractions of proteins, soluble at high salt concentration, and in the bottom panel (G-I) proteins, insoluble under native conditions are shown. Solid arrows in B and C indicate proteins, identified by MS directly from total yeast lysates, whereas dotted arrows point to the proteins, identified from soluble and insoluble fractions. M – MW markers
EM of recombinant human parainfluenza virus 1 and 3 nucleocapsid proteins in yeast Saccharomyces cerevisiae (Juozapaitis M et al., 2007).