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SUMMARY:Bacterial chemotaxis - Professor Howard Berg\, Herchel Smith Profe
 ssor of Physics and Professor of Molecular and Cellular Biology\, Harvard 
 University
DTSTART:20120201T163000Z
DTEND:20120201T173000Z
UID:TALK36147@talks.cam.ac.uk
CONTACT:Suzy Blows
DESCRIPTION:A great deal is known about the motile behavior of Escherichia
  coli.  I will tell you some things about the history of this subject and 
 then describe two recent vignettes\, involving adaptation at the output of
  the sensory-transduction pathway\, and growth of flagellar filaments.  1)
  Receptor methylation and demethylation are required for adaptation on the
  second time scale\, which enables cells to make temporal comparisons and 
 swim up spatial gradients of attractants.   In the absence of the methyltr
 ansferase and the methylesterse\, one still observes partial adaptation\, 
 on the minute time scale.  The motor shifts its operating point to accommo
 date new steady-state levels of the response regulator CheY-P.  When the c
 oncentration of CheY-P decreases\, the number of copies of the protein to 
 which CheY-P binds\, FliM\, increases.  2) Flagellar filaments grow at the
 ir distal ends.  The dogma in the field asserts that they do so at a rate 
 that decreases exponentially with length.  By labeling filaments twice\, f
 irst with a green fluorescent dye and later with a red fluorescent dye\, w
 e find that filaments grow at a constant rate.  On average\, the lengths o
 f red segments do not depend upon the lengths of green segments from which
  they grew.
LOCATION:Lecture Theatre 1\, Department of Veterinary Medicine
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