lo1 Nucleosomes and histone tails

What is the basic repeating unit of chromatin structure?

A nucleosome

How many histone molecules make up a nucleosome core particle?

Eight histone molecules

How many DNA base pairs wrap around the nucleosome core particle?

146-147 base pairs

What are the four core histone proteins?

Histone 2A (H2A), Histone 2B (H2B), Histone 3 (H3), and Histone 4 (H4)

What is the linker histone?

Histone 1 (H1)

How many of each core histone form the octameric nucleosome core particle?

Two of each core histone

Which histone tails protrude from the nucleosome?

N-terminal tails protrude for H3, H4, and H2B; N- and C-terminal tails protrude for H2A

What type of structure do histone tails have?

They are intrinsically disordered

Why are histone tails described as intrinsically disordered?

They are highly flexible and can move dynamically to perform different functions

Histones are basic proteins. What does this mean for their interaction with DNA?

They contain many positively charged arginine and lysine residues, allowing them to bind tightly with the negatively charged phosphate groups of DNA

Who proposed the nucleosome hypothesis and in what year?

Roger Kornberg in 1974

Who published the crystal structure of the nucleosome in 1997?

Luger, Mader, Richmond, Sargent & Richmond

Are histone tails heavily post-translationally modified?

Yes

Where do the N-terminal tails of core histones protrude from?

They protrude from the nucleosome