Biophysical Society Bulletin | July/August 2021

InMemoriam

GerhardMeissner

skeletal muscle. While working with Fleischer at Vanderbilt, he developed zonal centrifugation to purify sarcoplasmic reticulum vesicles from rabbit skeletal muscle, launching an uninterrupted engagement with the nanomachine responsible for regulating local extracellular Ca ++ concentrations and, implicitly, induction of muscle contraction. The dominant protein in these prepara- tions was the Ca ++ pump, a 2.3million kD tetrameric ion channel referred to as the ryanodine receptor based on its high affinity for the plant alkaloid ryanodine. In 1988, Meissner’s team reconstituted the ryanodine recep- tor into lipid bilayers and with Harold Erikson revealed its intact four-leaf-clover structure by electronmicroscopy. The continuity of the clover leaf structure with the transverse-tubule sarcoplas- mic reticulum junction in intact skeletal muscle images implied for the first time that excitation-contraction coupling works by opening and closing the Ca ++ release channel. Reconstitution and the subsequent molecular cloning of genes for the Ca ++ channel defined an in vivo system, enabling Meissner to characterize the highly coupled influences of Ca ++ , other ions, and various allosteric effectors such as ryanodine on channel function. Those studies facilitated single-channel studies that defined the channel con- ductance and gating properties. Subsequent collaboration with Jonathan Stamler showed that many cysteine residues in cardiac muscle Ca ++ channels are subject to poly-S nitrosylation with nitric oxide, which activates channel activity. His recent work combinedmutational studies with computational analysis by Nikolay Dokholyan ’s group of the molecular determinants of gating and high ion flux through open channels based on emerging cryoelectronmicroscopic structures of multiple states of the Ca ++ channel assembly. — Charlie Carter

Gerhard Meissner (1937–2021), a bio- physicist known for his definitive stud- ies of the role of ryanodine receptor in Ca ++ regulation of muscle contraction, has died at his home in Chapel Hill, North Carolina, at the age of 84. Meiss- ner was a Professor in the University of North Carolina, at Chapel Hill Biochem- istry and Biophysics Department from 1974 until his death onMay 1, 2021. He was an Established Investigator of the American Heart Association from 1972–1977 and was elected a Fellow of the Biophysical Society in 1999.

Gerhard Meissner

Meissner was born inWilhelmshaven, Germany, on January 26, 1937. He received B.S. andM.S. degrees from the Free Univer- sity of Berlin and a PhD degree in Physical Chemistry from the Technical University of Berlin in 1965. He was a Gosney Fellow and Volkswagenstiftung Fellowwith Max Delbrück at the Califor- nia Institute of Technology. From1969–1974, he worked with Sydney Fleischer at Vanderbilt University, where he began work with the ryanodine receptor. Meissner joined the University of North Carolina at Chapel Hill in 1974 and was appointed Pro- fessor of Biochemistry and Biophysics in 1986. While at UNC Chapel Hill, he received continuous funding from the National Institutes of Health (NIH) that included two NIHMERIT Awards from1990–2000 and 2010–2021. He was revered by colleagues and students for his intellectual generosity and gentle sense of humor. Meissner’s interests centered on the structure and functional regulation of ion channels and calcium signaling in cardiac and

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