Tobin Fricke

University of Californiawith Asmahan Abu-Arish, Dr. Michael Elbaum & Dr. Sharon Wolf

3d reconstruction of a helical protein from electron microscopy

Infection by gene transfer from bacterium to plant

Growth factorEnzymes to produce opines

Can replace with other genes for transformationEvidence for gene transfer to animal cells

Agrobacterium tumefaciens

electron microscopy

• Just like optical microscopy, but with electrons instead of photons

tomography

• by looking through an object at many angles, determine its internal structure.

back-projection

back-projection

Helical symmetry

• Translation is equivalent to axial rotation

micrographs

particles

filament picking tool

automated picking

Results: T-complex structure

hollow helical tube

diameter 16 nmpitch 5.2 nm4.3 VirE2/turnshortening factor ~7

3-domain structure of VirE2

single-strand DNA lies on a shelf at the interior of the tube at radius ~5.5 nm

20 kb ssDNA: ext. length 8. m random coil ~90 nm