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UID:DSC-23081
DTSTART;TZID=Europe/Berlin:20260924T150000
SEQUENCE:1789537087
TRANSP:OPAQUE
DTEND;TZID=Europe/Berlin:20260924T160000
URL:https://dresden-science-calendar.de/calendar/en/detail/23081
LOCATION:MPI-CBG\, Pfotenhauerstraße 10801307 Dresden
SUMMARY:Murugasamy: Structural Studies of E. coli DNA Gyrase Complexes: Mol
 ecular Recognition of DNA Topology and Conformational Regulation
CLASS:PUBLIC
DESCRIPTION:Speaker: Naveen Kumar Murugasamy\nInstitute of Speaker: IGBMC\,
  Strasbourg\, France\nTopics:\n\n Location:\n  Name: MPI-CBG (MPI-CBG CBG 
 Galleria II (VC))\n  Street: Pfotenhauerstraße 108\n  City: 01307 Dresden
 \n  Phone: +49 351 210-0\n  Fax: +49 351 210-2000\nDescription: Maintainin
 g negatively supercoiled (-SC) topological homeostasis in the bacterial ch
 romosome is essential for genome stability\, replication fidelity\, and tr
 anscriptional regulation. As DNA and RNA polymerases track along the doubl
 e helix\, they generate mechanical stress\, producing downstream positive 
 supercoils (+SC) that can stall macromolecular machineries. In bacteria\, 
 the type II topoisomerase DNA gyrase uniquely relieves this topological st
 rain through a tightly regulated homeostatic feedback loop\, modulating gy
 rA and gyrB expression in response to DNA relaxation. While gyrase is know
 n to be biochemically versatile\, catalyzing ATP-dependent negative superc
 oiling\, ATP-dependent positive supercoil relaxation\, and ATP-independent
  negative supercoil relaxation\, its catalytic efficacy depends entirely o
 n its capacity to distinguish between these topological states. Despite ex
 tensive biochemical characterization\, the structural basis governing how 
 DNA gyrase senses DNA chirality and selectively engages supercoiled substr
 ates has remained fundamentally unresolved. To address this question\, thi
 s study presents high-resolution cryo-electron microscopy structures of DN
 A gyrase trapped in complex with (+) and (–) supercoiled minicircle DNA 
 substrates. By capturing these distinct topological assemblies\, the resul
 ting reconstructions reveal the critical C-terminal domain (CTD) interacti
 ons and large-scale conformational transitions that mediate chirality disc
 rimination and dictate the directionality of strand passage. Furthermore\,
  this study reports the structural determination of a novel DNA-free confo
 rmation of DNA gyrase\, a resting state intermediate hypothesized from kin
 etic experiments but never previously visualized at near-atomic resolution
 . Together\, these findings define the conformational steps leading to sup
 ercoil chirality sensing\, establishing a definitive mechanistic model for
  how DNA gyrase maintains topological integrity within the bacterial cell.
DTSTAMP:20260916T150507Z
CREATED:20260818T053853Z
LAST-MODIFIED:20260916T053807Z
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