An elegant analysis of protein assembly

A Nov. 7 "New and Notable" article by Yves Engelborghs in the Biophysical Journal describes an enthusiastically reviewed study of protein self-assembly by associate professors Marcia Levitus and Rebekka Wachter and coworkers. Both Levitus and Wachter are faculty members in ASU's Department of Chemistry and Biochemistry and Levitus is also part of the Center of Single Molecule Biophysics in ASU's Biodesign Institute.

The analysis of the polymerization of protein subunits is an old challenge that has never lost its importance. In fact this process could be a key to biological control. "Likewise, an increasing number of diseases are related to aberrant protein oligo- and polymerization," described Engelborghs.

“In land plants, Rubisco activase regulates the extent of atmospheric carbon fixation by coordinating the light and dark reactions of photosynthesis. Although protein self-association plays a critical role in this process, the activase assembly mechanism has remained elusive for many years,” explained Wachter.

Despite the significance of the problem, the assembly pathway of Rubisco activase has been difficult to track due to the different states of oligomerization of the proteins observed in these preparations. In this work, the authors used fluorescence techniques that rely on the measurement and analysis of very small numbers of molecules. 

"These techniques are convenient ways to study molecular diffusion and oligomerization without physical perturbation of the sample in a wide range of concentrations. Our results show clear evidence of the coexistence of multiple oligomerization states, and allowed us to propose possible mechanisms for the subunit association pathways of Rubisco activase," stated Levitus who is also part of the Center of Single Molecule Biophysics in ASU's Biodesign Institute. "In addition, the methodology that we developed in this work can be broadly used to investigate self-association in other proteins."