Bacterial genome structure, NAPs and transcription

Question 1

What is bacterial chromosome like?

Answer 1

-circular and simpler than euks
-v. densely coding
-few introns
-no repeating seqs
-mostly encodes prots or funct RNAs
-short intergenic distances

Question 2

How does DNA fit inside bacteria?

Answer 2

-genome constrained into domains by nucleoid-associated proteins (NAPs)
-supercoiling compacts DNA further (controlled by topoisomerases)

N/B: v. flexible (needs to be uncoiled for DNAP to access it)

Question 3

What are nucleoid-associated proteins?

Answer 3

proteins which constrain genome into domains
-most bact have multiple diff NAPs which differ in function (eg. E.coli has at least 6)

Question 4

What do topoisomerases do?

Answer 4

control supercoiling of DNA

eg. in E.coli topo2 (gyrase) introduces -ve supercoils, topo 1, 3 and 4 relax them

Question 5

What does H-NS (an E.coli NAP) do?

Answer 5

bridge between adjacent segments of DNA

Question 6

What do Fis and IHF (E.coli NAPs) do?

Answer 6

induce severe bends in DNA

Question 7

What does HU (an E.coli NAP) do?

Answer 7

condense DNA into a fibre
-most conserved NAP

Question 8

What do Dps and CbpA (E.coli NAPs) do?

Answer 8

condense DNA to protect it from damage
-expressed in stationary phase