RESEARCH INTEREST

Protein targeting and folding in plants AREAS: Oorganelle biogenesis, posttranslational modifications


RESEARCH

Plant cells contain many complex membrane-limited subcellular compartments whose proteins are synthesized primarily within the cytoplasm. A key question is how proteins get from the cytoplasm to their final location within the organelle. Further, how are proteins maintained in unfolded form during transit from the cytoplasm and then correctly folded and assembled within the organelle? It is known that a class of proteins, termed chaperones, assist this targeting, folding, and assembly.

One class of chaperones consists of proteins related to the 70,000 molecular weight heat-shock or stress-related proteins (Stress70s). Specific forms of Stress70 are located within all compartments. In the cytoplasm, Stress70 binds to the nascent polypeptide emerging from the ribosome and maintains it in an unfolded conformation. ATP is required and rates of ATP hydrolysis are regulated by covalent modification of the chaperones and by association with accessory co-chaperones. Conversely, organellar Stress70 assists in correctly folding a polypeptide once it is transported into the organelle interior. Current research focuses on the nature of the interactions between newly synthesized polypeptides, the Stress70 molecular chaperones, and the ATPase-regulating co-chaperones.

Localization of the atDjC6 and atDjC37 co-chaperone proteins by scanning laser confocal microscopy. Tobacco BY-2 cells were transformed by particle bombardment to to express atDjC6-GFP (B) and atDjC37-RFP (C). Where the green and red fluorescent images are coincident, the merged images appear as yellow (C). Panel A is a differential interference microscopy (Nomarski) image of the same cell.


SELECTED PUBLICATIONS

Hajduch, M., Hearne, L.B., Miernyk, J.A., Casteel, J.E., Joshi, T., Agrawal, G.K., Song, Z., Zhou, M., Xu, D., Thelen, J.J. (2010) Systems analysis of seed filling in Arabidopsis: Using general linear modeling to assess concordance of transcript and protein expression. www.plantphysiol.org/cgi/doi/10.1104/pp.109.152413.

Antoine W, Miernyk JA (2009) A multidimensional scaling-based model for analysis of time-index biomics data. Advanced Studies in Biology 1: 43-59

Antoine W, de los Reyes BG, Miernyk JA, Stewart JMcD (2009) Molecular evolution of the plant SLT protein family. Icfai Journal of Genetics and Evolution 2: 56-73

Miernyk JA, Thelen JJ (2008) Biochemical approaches for discovering protein:protein interactions. Plant Journal 53:597-609.

Antoine W, Miernyk JA (2007) Shape-to-string mapping: A novel approach to clustering time-index biomics data. Online Journal of Bioinformatics 8: 139-153

Miernyk JA, Szurmak B, Tovar-Mendez A, Randall DD, Muszynska G (2007) Is there a signal transduction pathway that links events at the plasma membrane to the phosphorylation state of the mitochondrial pyruvate dehydrogenase complex? Physiologia Plantarum 129: 104-113

Kojima M, Casteel J, Miernyk JA, Thelen JJ (2007) The effects of down-regulating expression of Arabidopsis thaliana membrane-associated acyl-CoA binding protein 2 on acyl-lipid composition. Plant Science 172: 36-44

Mooney BP, Miernyk JA, Greenlief MC, Thelen JJ (2006) Using quantitative proteomics to predict metabolic activity. Physiologia Plantarum 128: 237-250.