Magic Spot ppGpp (image) Penn State Share Print E-Mail Caption In 1969, Cashel and Gallant identified a magic spot (MS) that appeared on a chromatogram (left) made from bacteria that had been starved a key nutrient. This magic spot was later identified as ppGpp and shown to influence the expression of over 500 genes in response to stress. An innovative crystallization technique now has allowed researchers to determine the structure of ppGpp in complex with bacterial RNA polymerase and DksA (upper right). Credit Murakami Laboratory, Penn State Usage Restrictions Image credit must be published alongside the image. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.