All cells — bacterial or human — secrete up to 10 or 20 percent of the proteins that they make. Human secreted proteins, for example, include components of serum, hormones, growth factors that promote cell development during embryogenesis and tissue remodeling, and proteins that provide the basis for immune cell signaling during infection or when fighting cancer.
The secretion process, however, isn’t an easy feat for cells, as they need to move the proteins across a membrane through a channel. Transport requires the formation of a hairpin, formed by an initiator protein.
In a recent study, Don Oliver, the Daniel Ayres Professor of Biology, professor of molecular biology and biochemistry, and Ishita Mukerji, the Fisk Professor of Natural Science, professor of molecular biology and biochemistry, explain the importance of where and why hairpins form and how they help proteins move across the cell.
The study, titled “Alignment of the protein substrate hairpin along the SecA two-helix finger primes protein transport in Escherichia coli,” brings together key areas of membrane biochemistry, structural biology and molecular biophysics, and has innovative applications of molecular genetics and fluorescence spectroscopy. It was published in the Aug. 7 issue of Proceedings of the National Academy of Sciences (PNAS).