Aron and Imre Tauber Professor of Biochemistry and Molecular Pharmacology
Single-molecule Biochemistry and Biophysics. Transcription and RNA processing. Cytoskeletal networks and regulation.
Living cells are chock full of dynamic complexes of protein, RNA, and DNA molecules. We want to understand the fundamental chemical and physical mechanisms through which these molecular machines perform essential biological processes. Our research is focused in two different areas of study: 1) the function of the molecular machines essential to gene expression and its regulation, in particular those that control the synthesis and processing of messenger RNAs, and 2) the function of molecular machines essential to the organization and utilization of the actin and microtubule cytoskeleton of eukaryotic cells.
All of the processes that we study involve dynamic molecular assemblies and multiple reaction intermediates. It is challenging to study their mechanisms using conventional biochemical approaches because different individual molecules in a population are doing different things at the same time. To overcome this “crowd noise problem”, we have developed and used single-molecule light microscopy methods that allow us to observe the behavior of isolated individual molecules and molecular complexes in real time. Using these techniques we can directly observe the assembly, rearrangements, and disassembly of molecular complexes, characterize conformational changes, and detect biochemical reactions. Together, these methods permit comprehensive investigation of molecular mechanisms, revealing reaction pathways and allowing quantitative evaluation and modeling of reaction dynamics. We perform these single-molecule experiments both in systems reconstituted from purified componentsand in extracts that recapitulate the molecular complexity of the living cell.
Our research uses approaches from scientific fields ranging from cell biology and genetics through biochemistry and molecular biology to physical chemistry and condensed-matter physics. In our experience, the most exciting advances in science often arise when scientists from different disciplines collaborate.
- Gupta S, et al. A Helicase-tethered ORC Flip Enables Bidirectional Helicase Loading. eLife 2021 Dec 9;10:e74282 (2021).
- Baek I,. Molecular Cell 81, 3576-3588.e6 (2021). . Single-molecule studies reveal branched pathways for activator-dependent assembly of RNA polymerase II pre-initiation complexes
- Kim LDJ, et al. DDK regulates replication initiation by controlling the multiplicity of Cdc45-GINS binding to Mcm2-7. eLife 2021;10:e65471 (2021).
- Shekhar S, Hoeprich GJ, Gelles J, Goode BL. Twinfilin bypasses assembly conditions and actin filament aging to drive barbed end depolymerization. J Cell Biol. 2021 Jan 4; 220(1). doi: 10.1083/jcb.202006022.
- Rosen GA, Baek I, Friedman LJ, Joo YJ, Buratowski S, Gelles J. Dynamics of RNA polymerase II and elongation factor Spt4/5 recruitment during activator-dependent transcription. Proc Natl Acad Sci U S A. 2020 Dec 22; 117 (51):32348-32357. doi: 10.1073/pnas.2011224117.
Harden TT, Herlambang KS, Chamberlain M, Lalanne JB, Wells CD, Li GW, Landick R, Hochschild A, Kondev J, Gelles J. Alternative transcription cycle for bacterial RNA polymerase. Nat Commun. 2020 Jan 23; 11(1):448.
- Shekhar S, Chung J, Kondev J, Gelles J, Goode BL. Synergy between Cyclase-associated protein and Cofilin accelerates actin filament depolymerization by two orders of magnitude. Nat Commun. 2019 Nov 22;10(1):5319. doi: 10.1038/s41467-019-13268-1.
- Huang B, Friedman LJ, Sun M, Gelles J, Street TO. Conformational Cycling within the Closed State of Grp94, an Hsp90-Family Chaperone. J Mol Biol. 2019 Aug 9;431(17):3312-3323. doi: 10.1016/j.jmb.2019.06.004.
Champasa K, Blank C, Friedman LJ, Gelles J, Bell SP. A conserved Mcm4 motif is required for Mcm2-7 double-hexamer formation and origin DNA unwinding. Elife. 2019 Aug 6;8. doi: 10.7554/eLife.45538.
- Stumper SK, Ravi H, Friedman LJ, Mooney RA, Corrêa IR, Gershenson A, Landick R, Gelles J. Delayed inhibition mechanism for secondary channel factor regulation of ribosomal RNA transcription. eLife. 2019; 8.
- Guo S, Sokolova OS, Chung J, Padrick S, Gelles J, Goode BL. Abp1 promotes Arp2/3 complex-dependent actin nucleation and stabilizes branch junctions by antagonizing GMF. Nature communications. 2018; 9(1):2895.
- Braun JE, Friedman LJ, Gelles J, Moore MJ. Synergistic assembly of human pre-spliceosomes across introns and exons. eLife. 2018; 7.
- Chadda R, Krishnamani V, Mersch K, Wong J, Brimberry M, Chadda A, Kolmakova-Partensky L, Friedman LJ, Gelles J, Robertson JL. The dimerization equilibrium of a ClC Cl(-)/H(+) antiporter in lipid bilayers. eLife. 2016; 5.
- Friedman LJ, Gelles J. Multi-wavelength single-molecule fluorescence analysis of transcription mechanisms. Methods (San Diego, Calif.). 2015; 86:27-36.
- Ticau S, Friedman LJ, Champasa K, Corrêa IR Jr, Gelles J, Bell SP. (2017) "Mechanism and timing of Mcm2-7 ring closure during DNA replication origin licensing." Nature structural & molecular biology. 2017; 24(3):309-315.
- Tetone LE, Friedman LJ, Osborne ML, Ravi H, Kyzer S, Stumper SK, Mooney RA, Landick R, Gelles J. (2017) "Dynamics of GreB-RNA polymerase interaction allow a proofreading accessory protein to patrol for transcription complexes needing rescue." Proceedings of the National Academy of Sciences of the United States of America. 2017; 114(7):E1081-E1090.
- Hoskins AA, Rodgers ML, Friedman LJ, Gelles J, Moore MJ. (2016) "Single molecule analysis reveals reversible and irreversible steps during spliceosome activation." eLife (2016) 5:e14166.
- Harden TT, Wells CD, Friedman LJ, Landick R, Hochschild A, Kondev J, Gelles J. (2016) "Bacterial RNA polymerase can retain σ70 throughout transcription." Proceedings of the National Academy of Sciences of the United States of America. 2016; 113(3):602-7.
View Complete Publication List on PubMed: Jeff Gelles.