JOINT ICTP/SISSA STATISTICAL PHYSICS SEMINAR: " Agglomeration of DNA-looping proteins "

[CM ICTP - Trieste]

JOINT ICTP/SISSA STATISTICAL PHYSICS SEMINAR






Tuesday, 12 February    -    12:30 hrs.




Seminar Room-ICTP Main Building-1st floor






SUMEDHA
( ISI, Turin )





" Agglomeration of DNA-looping proteins "



Abstract

The transcriptional activity is not evenly distributed inside the cell, 
but it is concentrated in focal points around so-called transcription 
factories. The formation of transcription factories and DNA looping are 
considered to be of fundamental importance for the large-scale spatial 
organization of the transcriptional activity. We propose a 
thermodynamic mechanism for the formation of transcriptional foci via 
the joint agglomeration of DNA-looping proteins and protein-binding 
domains on DNA: The competition between the gain in protein-DNA binding 
free energy and the entropy loss due to DNA looping is argued to result 
in an effective attraction between loops. A mean-field description can 
be solved analytically via a mapping to a restricted random-graph 
ensemble. It shows the emergence of protein clusters containing a 
finite fraction of all looping proteins. If the entropy loss due to a 
single DNA loop is high enough, this transition is found to be of first 
order.