Contact Information:
Department of Chemistry
Texas A&M University
College Station, TX 77842
Phone: (979) 862-3188
Fax: (979) 862-3339
ajohnson@medicine.tamhsc.edu

Arthur Johnson
Distinguished Professor
Wehner - Welch Foundation Chair in Chemistry
Distinguished Professor of Molecular and Cellular Medicine
Professor of Biochemistry and Biophysics

Ph. D., University of Oregon

Awards:

• Helen Hay Whitney Fellow

Johnson Research Laboratory

We are primarily investigating two different biochemical processes in my laboratory: the movement of proteins through or into a membrane (protein sorting), and the creation of holes in mammalian cell membranes by bacterial toxins. To understand how these processes are accomplished and regulated at the molecular level, we have employed a variety of biophysical, biochemical, and other techniques to examine the interactions and molecular architecture of free and membrane-bound macromolecular complexes, as well as changes in structure that are functionally important. We use fluorescence resonance energy transfer (FRET), photocrosslinking, or chemical crosslinking to determine the spatial arrangement of individual components within the complexes and to quantify the magnitude of conformational changes in the complexes. We also use various fluorescence techniques to detect and characterize the molecular interactions and conformational changes involved in the assembly, function, and regulation of the complexes, as well as to determine the structure of membrane-bound complexes. For example, our unique spectroscopic approach revealed that secretory proteins pass through the ER membrane via an aqueous, gated pore, not through the hydrophobic interior of the phospholipid bilayer.

"The Molecular Mechanisms Underlying BiP-Mediated Gating of the Sec61 Translocon of the Endoplasmic Reticulum" Alder, N. N., Shen, Y., Brodsky, J. L., Hendershot, L. M., and Johnson, A. E. Journal of Cell Biology 168, 389-399 (2005).

"The Domains of a Cholesterol-Dependent Cytolysin Undergo a Major FRET-Detected Rearrangement during Pore Formation" Ramachandran, R., Tweten, R. K., and Johnson, A. E. Proceedings of the National Academy of Sciences (USA) 102, 7139-7144 (2005).

"The Co-translational Folding and Interactions of Nascent Protein Chains: A New Approach Using Fluorescence Resonance Energy Transfer" Johnson, A. E. FEBS Letters 579, 916-920 (2005). Nobel Symposium special issue.

"Fluorescence Approaches for Determining Protein Conformations, Interactions and Mechanisms at Membranes" Johnson, A. E. Traffic, in press (2005).

"Nascent Membrane and Secretory Proteins Differ in FRET-Detected Folding Far Inside the Ribosome and in Their Exposure to Ribosomal Proteins" Woolhead, C. A., McCormick, P. J., and Johnson A. E. Cell 116, 725-736 (2004).

"Membrane-Dependent Conformational Changes Initiate Cholesterol-Dependent Cytolysin Oligomerization and Intersubunit β-Strand Alignment” Ramachandran, R., Tweten, R. K., and Johnson, A. E. Nature Structural & Molecular Biology 11, 697-705 (2004).

"Cotranslational Integration and Initial Sorting at the Endoplasmic Reticulum Translocon of Proteins Destined for the Inner Nuclear Membrane" Saksena, S., Shao, Y., Braunagel, S., Summers, M. D., and Johnson, A. E. Proceedings of the National Academy of Sciences (USA) 101, 12537-12542 (2004).

Sadlish, H., Pitonzo, D., Johnson, A. E., and Skach, W. R. (2005) "Sequential Triage of Transmembrane Segments by Sec61α During Biogenesis of a Native Multispanning Membrane Protein," Nature Structural & Molecular Biology 12, 870-878.