Subgroups

BIV

BIV Subgroup Takes Exciting Journey Through in vivo Biophysics

As tools to study complex biological systems become more and more sophisticated, we are increasingly empowered with the ability to interrogate and understand the behavior of biomolecules in the context of the living cell and in complex cell-like environments. This fascinating, yet still poorly explored research area, is the focus of one of the youngest subgroups of the Biophysical Society, the Biopolymers in Vivo (BIV) subgroup, which was formed three years ago. The third BIV subgroup symposium was held at the recent Biophysical Society Annual Meeting in Philadelphia and featured a variety of stimulating lectures elucidating how the cellular context is able to shape macromolecular behavior.

One of the keynote speakers at the BIV symposium, Jacqueline Barton, explained that double-stranded DNA has the ability to mediate charge transport across long distances via its stacked aromatic bases. She pointed out that this ability is dramatically impaired in the presence of DNA mismatches or base-pair damage. The implications of Barton’s research are far-reaching: In the context of the living cell, this special function of DNA may be exploited in a variety of ways, for example by proteins devoted to DNA repair. We also heard from Yousif Shamoo on how cellular needs may be met through evolution of enzymatic properties. Shamoo also showed that one can carry out quantitative enzymology directly in living cells. This strategy has a two-fold advantage. On the one hand, it bypasses the need for tedious protein purification and, on the other, it takes the influence of the cellular environment into account. Another speaker, Patricia Clark, described how the bacterial cell requires a protein to fold and unfold to make its way between different compartments and to properly display deadly virulence factors on its surface.

The second keynote speaker of the BIV symposium was Stefan Hell, who explained the basis behind his pioneering super-resolution imaging methods, which break the diffraction limit and provide exquisite detail about cellular features. In other lectures, mechanisms of proteins involved in cell division were revealed via imaging by Jie Xiao, and John Briggs explained how he used cryo-electron tomography for protein structure determinations. Finally, Gael McGill explained how cellular processes can best be grasped by K-12 students through the use of graphical examples and movies rather than with traditional textbooks. The talk highlighted the nontrivial nature of the creative process that leads to the most effective, yet scientifically accurate, visual biophysical learning tools. Two excellent postdoctoral fellow talks were presented by Robert Crawford on single molecule fluorescence in living cells and Rudra Kafle on chromosomal DNA dynamics; both received a BIV travel award. All told, it was a wonderful session, and the room was overloaded with listeners. We thank our sponsors for making this possible: Applied Photophysics, Jasco, OLIS, Bruker, and GE.

In the coming year, we will strive to increase visibility of BIV (e.g., by proposing a workshop for the Annual Meeting, by going to other meetings and spreading the word) and to increase the number of members. We will have a logo competition for students/postdocs: stay tuned for the announcement of the rules! We are very excited about the growing importance of in vivo biophysics and hope that many of you will decide to become BIV members. With a critical mass it is easier to make a difference and to share scientific excitement about the world of in vivo biophysics!

Pernilla Wittung-Stafshede, Lila Gierasch, and Silvia Cavagnero
   Former, current, and future BIV chairs

MSAS

Membrane Structure Perturbation and Disassembly

This year’s Membrane Structure and Assembly Subgroup (MSAS) symposium in Philadelphia was dedicated to a variety of phenomena related to the permeabilization, solubilisation, and reconstitution of membranes. The session started with the presentation of the first Thomas E. Thompson Award to William Wimley, Tulane University. It was a particular highlight that Thompson attended the meeting and handed the award plaque to Wimley, his former graduate student. Noticing Thompson’s portrait on the award plaque, Wimley said he looked forward to Thompson watching over his shoulder from now on. In contrast, Wimley seems to have been less seamlessly supervised by Thompson back in his grad student times, and he obviously used this freedom wisely. The award money of $1,000, as well as the symposium as a whole, was sponsored by Avanti Polar Lipids.

Wimley’s award lecture presented an extensive screen identifying pore forming peptides with superior performance. Alan Grossfield presented MD simulations of lipopeptides, showing that and why anionic molecules can in fact be attracted by anionic lipids. Ole Mouritsen explained the effects of lysolipids on membranes and their potential applications for drug delivery systems, including so-called LiPLAsomes. Erwin London presented that techniques with very high spatial and temporal resolution can detect nanoscopic domains in membranes. He found detergent not to induce, but rather to coalesce such nanodomains into larger ones. One issue raised in the discussion after the talk was that domains of a few nanometers lack key properties of a phase as assumed for rafts. Potential biological functions of nanodomains are quite distinct from those postulated for rafts, unless certain proteins or other triggers coalesce or grow nanodomains in vivo. Sandro Keller showed that membrane proteins can substantially promote membrane reconstitution from micelles and how this process can be monitored by isothermal titration calorimetry and fluorescence correlation spectroscopy. Last but not least, Klaus Gawrisch outlined the amazing complexity of solubilizers and stabilizers needed for each step of isolating, purifying, and reconstituting recombinant cannabinoid receptor and described their potential functions. Overall, the issue of membrane-disintegrating agents will keep on being instrumental for a variety of topics and applications in biology and medicine.

All colleagues who are interested in our field are invited to be part of our community and asked to support it by being members of the subgroup. All members are encouraged to make a nomination for the 2014 Thomas E. Thompson award before May 1, 2013. The next MSAS chairs will be Felix Goni (2014) and Marjorie Longo (2015)—congratulations on your election and thanks to all candidates who agreed to run! Many thanks also to sponsors, members, and all attendees. We hope to see you in San Francisco next year!

Heiko Heerklotz
   Former MSAS chair

Membrane Biophysics

The Membrane Biophysics Subgroup activities took place on February 2–3, 2013, during the 57th Annual Meeting of the Biophysical Society in Philadelphia. The Subgroup Symposium this year, Macromolecular Complexes of Ion Channels and Transporters, was co-organized by Diomedes Logothetis, Virginia Commonwealth University, and Brad Rothberg, Temple University. The Symposium, held on Saturday, February 2, featured seven talks: Diomedes Logothetis presented work on reconstitution of purified components of the G protein signaling system with K+ channels in planar lipid bilayers as well as a three dimensional model of a GIRK1 complex with the Gbg subunits; Ming Zhou, Baylor College of Medicine, presented work on crystal structures of TrkA, a soluble RCK-containing protein, with and without the K+ transport protein TrkH, suggesting a mechanism of how ATP regulates the activity of the complex; Eitan Reuveny, Weizmann Institute, presented work on the ER membrane proteins SARAF that causes Ca2+- dependent inactivation of STIM in regulating the activity of the plasma membrane channel Orai; Bill Catterall, University of Washington, presented work on the regulation of Cav1.2 by a signaling complex involving AKAP and PKA and carried the mechanistic studies to transgenic mice with specific mutations at key phosphorylation sites to assess the cardiovascular effects of the defective PKA regulation of the channel; Bonnie Wallace, Birkbeck College of the University of London presented work on a high-resolution structure of the NavMs channel that provided insights as to the sodium ion selectivity filter and the resolved C-terminal domain; Kevin Foskett, University of Pennsylvania, presented work on two interacting proteins with the Mitochondrial Calcium Uniporter (MCU), MUC1 and MCUR1, that are components of the mitochondrial uniporter channel complex required for mitochondrial Ca2+ uptake; and H. Peter Larsson, University of Miami, presented work distinguishing the effects of different KCNE beta subunits on KCNQ1 voltage sensor movement versus gate opening, using voltage clamp fluorometry. Six sponsors (ChanTest, the journal Channels published by Landes Bioscience, Sutter Instrument, Automate Scientific, ALA Scientific Instruments, and nan]i[on) provided support for the Symposium and the coffee break.

Elections for the 2015 Chair of the Membrane Biophysics Subgroup were held during the coffee break. The group voted for Baron Chanda, University of Wisconsin at Madison, who promised to showcase state-of-the-art single molecule techniques in the study of structure-function of ion channels and transporters.

The Symposium was followed by the 2013 Kenneth S. Cole (KC) Award Dinner honoring this year’s recipient, Fred Sachs, University of New York at Buffalo. As the dinner was served, Elise Stanley, Toronto Western Research Institute, introduced Kenneth Cole and showed pictures of chambers she obtained from the Marine Biological Laboratories at Woods Hole, Massachusetts, among which was the first chamber used for voltage-clamp studies. As dessert was served, Sachs presented the major parts of his career path in his usual entertaining manner. His technical genius came through loud and clear throughout his illustrious career. He also did notmiss the opportunity to challenge all of us in the field with convincing single-channel looking records obtained when pressing a patch pipette onto sylgard. The dinner concluded the wonderfully rich day of science with the name of another giant in the membrane biophysics field added to the 40 past recipients that make the KC award the prestigious honor it is in this field.

On Sunday, February 3, four members of the subgroup served as judges for the Society’s Student Research Achievement Award (SRAA) Poster Competition. The four judges were Irena Levitan, University of Illinois, Chicago; Paul Slesinger, Mount Sinai School of Medicine; Stephen Tucker, Oxford University, United Kingdom; and Diomedes Logothetis, Virginia Commonwealth University.

Preparations for the 2014 meeting have already begun. The 2014 Subroup Chair, Henry Colecraft, Columbia University, along with the Treasurer, Christopher Ahern, University of Iowa, have started to assemble the exciting program focusing on the role of auxiliary subunits in shaping the function of ion channels and transporters, to gather the support of sponsors, to preside over the selection of the prestigious KC Award, and to prepare for another SRAA poster competition. Last but not least, the tireless support of the Biophysical Society staff, and particularly of Vida Ess, makes the activities of each subgroup happen seamlessly year after year. Their continuous support and guidance are greatly appreciated.

See you all in 2014 in San Francisco!

Diomedes E. Logothetis
   Former Membrane Biophysics chair

April 2013 Table of Contents