MSU Skol Tech DNA structure and packing

MSU & Skol. Tech DNA structure and packing

DNA structure DNA double helix: rules of complementarity

DNA structure DNA topology

DNA structure Topoisomerase II

DNA structure Bacterial nucleoid structure Microscopy image of bacterial chromosome 50 -400 supercolied loops

DNA structure DNA binding proteins used for bacterial DNA compaction

DNA structure Bacterial DNA binding proteins are expressed at different periods of growth curve

DNA structure Hi. C analysis of the bacterial DNA proximity Diagonal element Domain structure

DNA structure Hi. C analysis of the bacterial DNA proximity Domains are separated by highly expressed genes

DNA structure DNA compaction in eukaryotes: nucleus

DNA structure Nucleus structure

DNA structure Nuclear lamina structure

DNA structure Nuclear lamina is anchored at the nuclear inner membrane

DNA structure Nucleolus

DNA structure Interphase and mitotic chromosomes

DNA structure Chromatin compaction

DNA structure Nucleosome composition 2 x H 2 A 2 x H 2 B 2 x H 3 2 x H 4 DNA 146 bp H 1 linking nucleosomes

DNA structure Histone modifications

DNA structure Histone modification is needed for chromatin assembly

DNA structure Heterochromatin is specifically modified and replicated late

DNA structure Chromatin scaffold

DNA structure Condensin

Chromosome Centromere

Chromosome Yeast centromere

Chromosome Centromere of higher eukaryotes

Chromosome Another SMC protein - cohesin

Chromosome Function of cohesin

Chromosome Telomeres

Chromosome Telomere shortening

Chromosome Telomeres

Chromosome Telomeres contain special DNA structures, G quadruplexes

Chromosome Telomerase

DNA compaction Different compaction mechanisms in interphase and mitosis early G 1 late G 1 S 5 C data Mitosis G 1

DNA compaction Different compaction mechanisms in interphase and mitosis What does it mean? Interphase chromosomes: fractal globule, defined domains, fixed relative to the chromosome position, compact-to-compact, unfolded-to-unfolded

DNA compaction Different compaction mechanisms in interphase and mitosis What does it mean? Mitotic chromosomes: consecutive loops, NOT fixed relative to the chromosome position, NOT hierarchically folded, not necessarily, but possibly attached to a scaffold

Unusual nucleus Macro- and micronucleus in ciliates Macronucleus is transcriptionally active, but do not contain “normal” chromosomes Micronucleus us silent, but contains “normal” chromosomes

Unusual nucleus Macro- and micronucleus in ciliates Macronucleus is formed from micronucleus after conjugation

Unusual nucleus Macro- and micronucleus in ciliates During macronucleus maturation part of DNA is degraded, and when the rest of DNA is fragmented and amplified

Unusual nucleus IES Macro- and micronucleus in ciliates IES DNA in micronucleus DNA in macronucleus IES = internal eliminated sequence How IES are recognized? Sequences, resistant to elimination are present in macronucleus…

Unusual nucleus micronucleus Macronucleus maturation Global transcription Dcl 1 cleavage old macronucleus

Unusual nucleus old macronucleus Macronucleus maturation elimination of all RNA matching macronuclear DNA micronucleus Export to maturating micronucleus

Unusual nucleus Macronucleus maturation micronucleus in a state of maturation to macronucleus H 3 histone modification Elimination of IES micronucleus in a state of maturation to macronucleus