Lecture 1-DNA Structure (Rosenthal) Flashcards
DNMT1
sister strand methylation
DNMT3B (or A) When do you see this expressed?
- de novo methylation
- early in development
NOTE: this family is a group of paralogs, all found on different chromosomes
ICF
disease resulting from a mutation in DNMT3B
What does it mean if a nucleotide is exo or endo? (Puckered formations)
- this has to do with whether the C2 or C3 is in the plan of the base
- exo: C2 or C3 is NOT in the plane of the base
- endo: C2 or C3 is in the plane of the base
Z DNA form is assumed when ______
the DNA is in a left handed turn, highly methylated
How much of human DNA is genes?
30% (1.5% exons)
How much of the DNA is transposons?
45%
What’s the most defining feature of ICF?
- loss of methylation from centromeric and pericentromeric regions of DNA
- inability of chromosomes to condense during mitosis
- subcellular distribution of chromatin proteins
- NOTE: physical manifestations include immunodeficiency, facial abnormalities, mental retardation
Which chromosomes are more affected in ICF?
- 1
- 9
- 16
What is special about the histones at the centromeres?
marked by an H3 variant
Where are most minisatellies found?
sub-telomeric region (90%)
What does H3 do?
It has a long branch that acts like a sensor for the environment and can transduce signals
What does H1 do?
- Compaction: responsible for solenoid structure (6 nucleosomes creating the cross section of 30nm fiber)
- holds DNA to chromosomes
Mitogenic H3 Kinases
phosphorylate H3 (10) to promote acetylation (9, 14) of H3 during interphase
Mitotic H3 kinases
- phosphorylate H3 (10, 28) to condense it for mitosis
Cohesins
- on chromosomes, tether chromatids together for replication
Condensins
keep chromatids in a condensed state
What proteins promote deacetylation (in order)?
- DNMT3B
- MeCP2
- Class 1: HDAC1,2,8
What proteins promote acetylation?
- P90rsk2: RSK family of kinases (ribosomal S6 kinase family), phosphorylates S10 of H3
- CREB-binding Protein (CBP): HAT
Histone acetylation decreases chromatin affinity for _____
H1
Rett Syndrom from a mutation in ____
MeCP2–X DOMINANT–RARE!
Rett Syndrome usually affects
females, males usually die
Coffin-Lowry syndrome is a mutation in_____ and what is its hereditary style?
- RSK2
- X-linked Dominant
Rubenstein Taybi syndrome is a mutation in _____ and has what inheritance style?
- CBP
- Autosomal Dominant
Which diseases result in chromatin that can’t condense?
- ICF (DNMT3B)
- Rett syndrome (MeCP2)
Which diseases result in chromatin that can’t decondense?
- Coffin-Lowry Syndrome
- Rubenstein-Taybi Syndrome
