Proteins act as chaperones

Dr. Ackerman is trying to understand how subunits of the ATP synthase come togeather to form the enzyme's structure.

Even newly dating teenagers can’t complain about the type of chaperones Sharon Ackerman, PhD, is studying.

The assistant professor of surgery and biochemistry/molecular biology, has identified two proteins that act as chaperones in assembling the enzyme ATP synthase. Like their human counterparts who make sure the evening goes smoothly without turning the date into a threesome, these proteins help build the ATP synthase without becoming part of the final enzyme.

An understanding of this chain of events is important for a couple of reasons, Dr. Ackerman said. The mitochondrial ATP synthase makes most of the ATP in the cells of all living things "so it’s very important from the standpoint of energetics. And it’s also somewhat interesting from the standpoint of determining how proteins help to mediate the assembly of other proteins." Her research has both in mind, she said. "We have the specific question in that we are interested in the ATP synthase, but, taking a step back from that, we’re also interested in the whole aspect of protein folding and protein assembly."

Dr. Ackerman, along with graduate student Dmitry Sheluho and post-doc Zhen-Guo Wang, has a four-year, $700,547 grant from the National Institutes of Health. Together, they are studying ATP synthase biogenesis using Saccharomyces cerevisiae, Baker’s yeast, as a model system. Although single-celled, this organism contains all of the eukaryotic organelles. "We can do biochemistry and also use genetic methods and molecular biology, because everything’s worked out very well for that organism," she noted.

There is interest worldwide to understand structure/function relationships in the ATP synthase; principal achievements in this area were honored recently with the awards of two Nobel prizes in chemistry. Dr. Ackerman’s approach to this area of research is to understand how the various subunits of the ATP synthase come together to form the enzyme’s structure. This investigation led to the identification of the protein chaperones, known as Atp11p and Atp12p. "(These) proteins seem to serve as molecular chaperones in that they help to assemble the ATP synthase, although once they’re finished, they’re not part of the final enzyme structure," she said. "Hence, they have a chaperone-type function."