Lecture 10 - Chromatin in Archea Flashcards
Why does E. coli use a combination of Nucleoid Associated Proteins (NAPs)?
They have overlapping binding sites
In the case of paralogues
Composition changes along with growth condition changes
How are archaic histones similar to eukaryotic histones?
Similar interactions with DNA: The helix proteins and histone dimers interact in a handshake-like conformation.
They have a similar binding preference
How were hypernucleosomes discovered, and what were the findings?
An MNase digestion of isolated chromatin was performed using EDTA
DNA was isolated from histone proteins and gel electrophoresis was performed.
Next-generation sequencing was then performed
Results showed in archaea, 30bp are bound by each histone dimer
Describe the Histone variant MJ1647
Different from canonical archaea, as they have a 27 amino acid extension at the carboxyl end
Form tetrameric complexes via the amino acid extension
Do not form heterodimers with canonical histones
EMSA of 60bp showed 1 band with MJ1647, compared to 2 with canonical histones, showing it wraps 60bp of DNA compared to 30bp
Compacts DNA in a cooperative manner
Effectively binds and bridges DNA double strands
Structural model revealed 2 DNA binding sites
