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DTSTAMP:20260406T000412Z
UID:5be185941deaf643685389@ist.ac.at
DTSTART:20190118T130000
DTEND:20190118T140000
DESCRIPTION:Speaker: Jan Löwe\nhosted by Martin Loose\nAbstract: Most\, if
  not all bacterial and archaeal cells contain at least one protein filamen
 t system. While these filament systems in some cases form structures compa
 rable to eukaryotic cytoskeletons\, the term prokaryotic cytoskeletons is 
 used to loosely and non-exhaustively refer to many different kinds of prot
 ein filaments united by the functional properties which stem ultimately fr
 om polymerisation\, and the resulting ability to access length scales bigg
 er than the size of the monomer. Prokaryotic cytoskeletons are involved in
  many fundamental aspects of cell biology\, and are most prevalent in proc
 esses of cell shape determination\, cell division\, and non-chromosomal DN
 A segregation. Some\, but by no means all\, of the filament-forming protei
 ns fall into a small number of conserved groups\, in particular the almost
  ubiquitous tubulin and actin families that also include ubiquitous eukary
 otic F-actin and microtubules. Bactofilin proteins form filaments and are 
 widespread amongst prokaryotes\, but do not belong to the tubulin and acti
 n superfamilies. Discovered only a few years ago\, their functions in cell
 s remain loosely defined\, appearing as spatial organisers close to bacter
 ial membranes. Bactofilins polymerise from small beta-helical subunits\, b
 ut the precise filament architecture and the nature of their membrane loca
 lisation have remained elusive.We have solved the structure of bactofilin 
 filaments from T. thermophilus to 4 Å by cryo-EM\, showing continuous bet
 a helical tubes that are made from subunits in a head-to-head arrangement\
 , leading to non-polar filaments. Mutating one filament interface leads to
  non-polymerising dimers that we could crystallise\, re-enforcing the non-
 polar nature of the native filaments. We show that T. thermophilus bactofi
 lin\, and most likely all bactofilins\, binds liposomes and membranes dire
 ctly. Hydrogen exchange coupled with mass spectrometry indicates that both
  N-and C-terminal tails of bactofilin are disordered and through a number 
 of experiments we show that the filaments bind membrane through the N-term
 inal tail. We also demonstrate that some fungi contain polymerising bactof
 ilin domains\, indicating that these filaments are not restricted to proka
 ryotes.To showcase the surprising diversity of the bacterial cytoskeleton\
 , I will also present recent data on bacterial mini microtubules (BtubAB) 
 and a cryo-EM structure of MinCD filaments.
LOCATION:Mondi Seminar Room 2\, Central Building\, ISTA
ORGANIZER:rsix@ist.ac.at
SUMMARY:Jan Löwe: The structure of bactofilin filaments and other wonders 
 of the bacterial cytoskeleton
URL:https://talks-calendar.ista.ac.at/events/1736
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