Circadian rhythm
• March 14 1088
• tongli zhang
Circadian rhythm
Circadian rhythms in different organisms
• Control network in mammalian
Circadian rhythms in Cyanobacyteria
cyanobacteria
Their interaction
• KaiA, KaiB and KaiC interact with each other, forming large complexes in vivo.
• KaiC is the core of the complex.
• The complex is mainly at night.
kaiC
KaiA
• kaiA enhances KaiC phosphorylation• KaiA has two domains- N-terminal is a
“pseudo-receive” domain• N-terminal domain of KaiA does not
promote KaiC autophosphorylation• KaiA from anabaena even does not have a
N-terminal domain• However, mutation of N-terminal domain
of KaiA lengthen the circadian period
KaiA 2
• KaiA C-terminal binds KaiC and promotes its phosphorylation
• One KaiA is enough to enhance the phosphotylation of one KaiC hexamer
KaiA 3
• KaiA exists as a domain-swapped homodimer• KaiA's pseudo-receiver domain• The C-terminal domain of KaiA, C-KaiA, is all a-
helical and adopts a novel dimeric structure.
KaiA 4 open and close
• kaiA dimerN of one and C of another interact
• This is closed • When the interaction
is broken- KaiA dimer is open
• Closed is supposed to be the active form
kaiC binding with KaiA
kaiB
• Positively charged residues R23 and K75
kaiC binds with KaiB
• The potentials (positive, blue; negative, red)
A rotary clock
Happy everyone?
• What about
• 1. entrainment?
• 2. temperature compensation?
• 3. fitness?
• 4. cancer development?
Way to solutions.