John Bennet Fenn was born in New York City on June 15, 1917. He received a B.A. in Chemistry from Berea College and earned a Ph.D. in chemistry at Yale University three years later. Fenn spent over a decade in industry, first at the Monsanto Chemical Co. in Anniston, Alabama, and later at Experiment Incorporated in Richmond, Virginia, where his work led to employment as the director of Project SQUID, an Office of Naval Research program focused on jet expansions.

His first faculty appointment came in 1957 at Princeton University as a Professor of Aerospace Sciences; he returned to Yale in 1967 as a Professor of Applied Science and Chemistry. During his tenure at Yale, Fenn’s research focused on molecular beam and supersonic jet expansion experiments. Presented by colleagues with the problems involved in ionizing large biomolecules for mass spectrometric analysis, John Fenn, at nearly 65, embarked on a new research trajectory, one which would lead to the development of a practical electrospray ionization source.

In 1994 he moved his research lab to Virginia Commonwealth University where he was appointed Research Professor of Analytical Chemistry. This move allowed Fenn to continue his research program, producing more than 20 additional papers. It also provided the opportunity to interact with students and faculty on a daily basis, as he continued to inspire undergraduates, graduate students, postdocs and colleagues.

Fenn’s research garnered wide recognition across a variety of fields with the ultimate honor being a share of the 2002 Nobel Prize in Chemistry for his development of electrospray ionization mass spectrometry.

Fenn’s professional honors include:

• ASMS Distinguished Contribution Award (1992)
• ACS-DAC award for Advances in Chemical Instrumentation (2000)
• Election to the American Academy of Arts and of Science (2000)
• Thompson Medal from ISMS (2000)

Protein conformation is dynamic as it is influenced by post-translational modifications (PTMs) and interactions with other proteins, small molecules or RNA, for example. However, in vivo characterization of protein structures and protein structural changes after perturbation is a major challenge. Therefore, experiments to characterize protein structures are typically performed in vitro and with highly purified proteins or protein complexes, revealing a static picture of the protein.

To identify the true conformational space occupied by proteins in vivo, we developed a novel low-resolution method named Covalent Protein Painting (CPP) that allows the characterization of protein conformations in vivo. Here, we report how an ion channel, the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR), is conformationally changed during biogenesis and channel opening in the cell.

Our study led to the identification of a novel opening mechanism for CFTR by revealing that the interaction of the intracellular loop 2 (ICL2) with the nucleotide binding domain 2 (NDB2) of CFTR is needed for channel gating, and this interaction occurs concomitantly with changes to the narrow part of the pore and the walker A lysine in NBD1 for wt CFTR. However, the ICL2:NBD2 interface, which forms a “ball-in-a-socket” motif, is uncoupled during biogenesis, likely to prevent inadvertent channel activation during transport. Mutation of K273 in the ICL2 loop severely impaired CFTR biogenesis and led to accumulation of CFTR in the Golgi and TGN.

CPP further revealed that, even upon treatment with current approved drugs such as Trikafta or at permissive temperature, the uncoupled state of ICL2 is a prominent feature of the misfolded CFTR mutants ∆F508 and N1303K that cause Cystic Fibrosis (CF). Although Trikafta treatment reduced the amount of uncoupled ICL2:NBD2 interfaces, more than 75% of F508 CFTR remained in the uncoupled state, suggesting that stabilization of this interface could produce a more efficient CF drug. CPP can characterize a protein in its native environment and measure the effect of complex PTMs and protein interactions on protein structure, making it broadly applicable and valuable for the development of new therapies.