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VERSION:2.0
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CALSCALE:GREGORIAN
BEGIN:VEVENT
DTSTAMP:20260727T220012Z
UID:ba7b10c5-080d-4c62-900e-0e22386c452b
DTSTART:20260729T090000Z
DTEND:20260729T170000Z
DESCRIPTION:|   **Wednesday\, July 29\, 2026** **14h GMT** **[Convert to y
 our time zone](https://eur03.safelinks.protection.outlook.com/?url=https%3
 A%2F%2Fn6b51.r.sp1-brevo.net%2Fmk%2Fcl%2Ff%2Fsh%2F7nVU1aA2nfsTSXsHyoEjgaDf
 OGZ7QUD%2FwIHLIzerwrNw&amp\;data=05%7C02%7Csilvana.westbury%40diamond.ac.u
 k%7Cf25406210eca4f81a90208dee8d7d970%7C9d27ba7401004d0d81ff1d728dae8df6%7C
 0%7C0%7C639204210940267180%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWU
 sIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%
 7C%7C%7C&amp\;sdata=wDz0hIikRLIvFsZvbyu%2BpxxAdxmA93YxGOKMM3zHD%2BQ%3D&amp
 \;reserved=0)**   **Structural Basis of Bidirectional Fork Initiation by 
 SV40 LTag Helicase** |\n| **Dr. Ammar Danazumi** [**Biomedical Sciences Di
 vision**](https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%
 2Fn6b51.r.sp1-brevo.net%2Fmk%2Fcl%2Ff%2Fsh%2F7nVU1aA2nfuMS4NaxNTBiwXTYd3uA
 Qj%2Fpryl3JHy0ChD&amp\;data=05%7C02%7Csilvana.westbury%40diamond.ac.uk%7Cf
 25406210eca4f81a90208dee8d7d970%7C9d27ba7401004d0d81ff1d728dae8df6%7C0%7C0
 %7C639204210940285942%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYi
 OiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C
 %7C&amp\;sdata=uEbgL51Xp%2Bkz5IBlM38ReG0dfAhfhMqk8BNmfGRkgm8%3D&amp\;reser
 ved=0) [**King Abdullah University of Science and Technology**](https://eu
 r03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fn6b51.r.sp1-brevo.
 net%2Fmk%2Fcl%2Ff%2Fsh%2F7nVU1aA2nfwFRastvwhdlIrHizYguNF%2FGCEuHjHmWlFr&am
 p\;data=05%7C02%7Csilvana.westbury%40diamond.ac.uk%7Cf25406210eca4f81a9020
 8dee8d7d970%7C9d27ba7401004d0d81ff1d728dae8df6%7C0%7C0%7C63920421094030611
 4%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAi
 OiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&amp\;sdata=2XVCs
 us45m%2BPAZA1dIk61rQelKQ1Xa3RDGUHDCg9HJs%3D&amp\;reserved=0) |\n\n| **Abst
 ract**   In eukaryotes\, DNA replication is initiated when two ring-shape
 d hexameric helicases load at defined DNA sites\, called origins\, and eng
 age one another in a head-to-head arrangement. Acting as a double hexamer\
 , they open the origin duplex and set up two divergent replication forks\,
  exposing the single-stranded templates that replicative polymerases requi
 re.    To define the structural events underlying this initiation step\,
  we used cryo-electron microscopy (cryo-EM)\, taking the SV40 Large Tumour
  Antigen as a tractable AAA+ helicase that recapitulates central features 
 of the eukaryotic replication machinery. We found that each helicase engag
 es and melts its own half of the origin in a manner that is both independe
 nt and symmetric. Local melting spans a minimum of five base pairs across 
 the early-palindrome and AT-rich elements of the origin and depends on the
  stepwise addition of LTag subunits\, on ATP binding\, and on a reorganisa
 tion of the helicase’s DNA-binding loops\, which switch from a planar to
  a staircase-like spiral arrangement as they contact the DNA tracking stra
 nd.    Together\, these events drive strand separation inside the helica
 se channel and leave each hexamer poised for ATP-powered translocation. We
  propose a model in which the duplex is subsequently sheared and the two h
 elicases decouple\, yielding bidirectional replication forks. The high con
 servation of the hexameric helicase core points to a general mechanism tha
 t extends from SV40 virus to the replicative helicases of eukaryotes. |
LOCATION:Online
SUMMARY:Biophysics in Africa Monthly Zoominar
URL;VALUE=URI:https://us02web.zoom.us/meeting/register/tZ0vc-GgpjsrE9YXHUuK
 upHJWWsMxzdPa4Tg#/registration
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