Barrels, magnets, and flying insects

Bunch of new reviews by Brandeis authors in press, check one out if you need to catch up on the state of the art.

• Lisman J, Yasuda R, Raghavachari S. Mechanisms of CaMKII action in long-term potentiation. Nat Rev Neurosci. 2012.
• Griffith LC. Identifying behavioral circuits in Drosophila melanogaster: moving targets in a flying insect. Curr Opin Neurobiol. 2012.
• Hedstrom L. The dynamic determinants of reaction specificity in the IMPDH/GMPR family of (beta/alpha)(8) barrel enzymes. Crit Rev Biochem Mol Biol. 2012.
• Pan Y, Du X, Zhao F, Xu B. Magnetic nanoparticles for the manipulation of proteins and cells. Chem Soc Rev. 2012.

Trimethoprim decorated beads for magnetically manipulating mammalian cells

Brandeis grad students Yue Pan (Chemistry) and Marcus Long (Biochemistry), together with postdoc Hsin-Chieh Lin and Professors Lizbeth Hedstrom and Bing Xu, have extended their previous work on 6 nm diameter magnetic nanobeads (comparable in size to a globular protein). They’ve shown that when decorated with the ligand trimethoprim, the nanobeads can be used to selectively bind to target E coli DHFR fusion proteins, and in addition can be used to manipulate live cells with a magnetic force. This work entitled “Cell Compatible Trimethoprim (TMP)-Decorated Iron Oxide Nanoparticles Bind Dihydrofolate Reductase (DHFR) for Magnetically Modulating Focal Adhesion of Mammalian Cells” is now online in the Journal of the American Chemical Society (JACS).

These small, magnetic beads are the first example of solid supported trimethoprim and have numerous advantages over larger traditional beads, including rapid purification, and ultra low non-specific binding. It is, however, their ability to affect live cells that is most important. In the paper they first show that Cos-1 and HeLa cells can be incubated with the beads for over 5 days with little cell death. These cells can subsequently be manipulated by transfection. Finally when exposed to a magnetic force, the focal adhesion of bead-treated Cos-1 cells can be manipulated.

See also: recommendation at Faculty of 1000

Separating proteins and manipulating live cells using magnetic nanoparticles

Brandeis grad students Yue Pan (Chemistry) and Marcus Long (Biochemistry), together with Professors Lizbeth Hedstrom and Bing Xu, have synthesized novel 6 nm diameter magnetic nanobeads (comparable in size to a globular protein) and used them to separate specific proteins from a cell lysate and manipulate live cells. This work has just appeared online in the journal Chemical Science.

Selectively binding glutathione-S-transferase fusion proteins using
glutathione-decorated iron oxide nanoparticles and down-stream applications

These small, magnetic beads have numerous advantages over larger traditional glutathione-modified beads, including rapid purification, and ultra low non-specific binding. Importantly, both the purified GST and the protein of interest (POI) preserve their innate properties. They also demonstrate that functionalized iron oxide nanoparticles can be used to manipulate live cells. This work  establishes design principles for decorating magnetic nanoparticles that will ultimately should lead to a general and comprehensive platform for studying biological interactions and biological systems using a magnetic force.