lecture 3 Flashcards
(42 cards)
how is the chromosome compacted?
Compacted in an orderly and hierarchical fashion with a functional three dimensional form to allow replication , recombination, segregation, and transcription
what is the genetic map?
organization of the chromosome within the bacteial cell
what controls the chromosome architecture?
Controlled by specialized proteins
what are some methods for visualizing the bacterial chromosome?
cryo electron tomography
super-resolution microscopies
what is the structure of the chromosome?
Overall curved shape
- bundles at the central core and low-debsuty regions
what are the features of cryo electron tomography?
bacteria within native condition
has biological context
is high resolution
Low contract
is just a snapshot
what are the features of super-resolution microscopies?
The bacteria are live
Has functional context
it is fast and easy
Has low resolution
hard labeling
what is the structural organisation of the bacterial chromosome?
- The chromosome is compacter in an orderly and hierarchical fashion in lockstep with DNA replication
- It is not enclosed by a membrane
- The organization of the chromosome within the bacterial cell recapitulates the genetic map
- The chromosome is organized at different scales
what are CIDs?
Chromosome interaction domains
what are features the chromosome interaction domains?
- insulated from flanking regions, self interactions
- 10^2-10^3 kbp
- boundaires between CIDs: highly expressed genes
- HEG- house keeping genes (ribosomal gene cluster)
how does the number of CIDs differ?
depending on growth conditions
what are the important positions within the bacterial chromosome?
- replication (oriC) - one pole
The replication terminus (ter) - opposite pole
pole-anchoring proteins - Left and right chomosomal arms
what determines chromosome configuration?
Chromosome configuration is different in different bacteria and depends on the growth conditions
what does the ori-ter pattern determine?
Each daughter cell inherits a full copy of the genome
what happens during replication to the DNA?
During replication the new DNA moves to its relative position
what shape are bacterial chromosome?
Most bacterial chromosomes are circular but some are linear
what is the role of MatP in E.coli?
Keeps Ter in a compacted form
MatP binds to 13-bp matS sites present exclusively in the ~800-kb Ter macrodomain
MatP binds the matS site as a dimer
interacts with membranes
what is the function of NAPs?
They govern DNA organization
how is eukaryotic DNA organized?
Genomic DNA is condensed using histones (identical repeating octamers)
how is bacterial DNA organized?
organized plectonemic supercoiled using specific proteins
what are NAPs?
nucleoid-associated proteins
what are the structural maintenance complexes of chromosomes?
- ‘hinge’ dimerization domain
- an antiparallel coiled-coil ‘arm’ extending between the hinge and head domains
- ATPase ‘head’ domain
- Kleisin-interacting winged tandem elements (kite)
what are DNA loop extrusion mechanisms?
- embracing a pair of DNA segments in a signle ring
- dimerization of two rings
what are the structure of histone-like nucleoid structuring protein (H-NS)?
-small polypeptide; binds the DNA minor groove using a C-terminal arginine hook motif
- AT rich segments
- head-to-head: H-NS-DNA filaments
- Tail-to-tail DNA-H-NS-DNA bridges
- can occlude RNAP binding sites or transcription activators-> gene epxression
