folding of thermophilic c-domain i m r g = 46 Å n r g = 38 Å i m state never populates i m state...

Folding of thermophilic C-domain

Im Rg = 46 Å

N Rg = 38 Å

• IImm state never populates state never populates

It Rg = 60 Å

• On pathway foldingOn pathway foldingP15.1

GU

C

U

U c A u G c U C G GGUAAUC

G

A

A A A C C CA A A U

gaUGGUA

GGGGcAC CU U C c c

gA a G GA

AaUg

AACG

GAGGGAAGG

ACAGg cgcau

gcC

UGU

AUAGAUGAUUaCC GC

CgGA G

UACGA G

GcGc a

aAG

CC G

cUU

GCAGUACGAaG

G u A C AgAACAUGGCUU

A

uAGAgCaUgAGA

CCACUU

GUCC

UGCUCGC

ACGGU

GCUG

AGAUGCCCGU

AGUG U

G C G A G

CUGCgGccuuug g g C c GU AG

AGGAAA

1 20

40

60

260

280

300

320

340

360

380

250

80

P1P2

P4

P15

P18

P19

P3

P5

P5.1

5'

3'

G

U

U

C

C

AG

A

A

g c

gca

g

400

420

g

c

AG

L1

B. stearothermophilus

Rg = 60 Å

MgMg2+2+ conc. reaches K conc. reaches KMgMg((IImm-to--to-NN) ) firstfirst

Rg = 60 Å

99.98%

0.01% 0.01%

Neither Neither IImm nor nor NN populates yet populates yet

0.1%

Rg = 60 Å

Rg = 46 Å

Rg = 38 Å

10%90%

N starts accumulating, It still dominantsIItt is the is the reference statereference state for the stability of for the stability of NNIImm is is not importantnot important for the stability of for the stability of NN

Rg = 60 ÅRg = 38 Å

50%

MgMg2+2+ conc. reaches conc. reaches KKMgMg(functional)(functional)

49.5%

~ KMg(It-to-N)

0.5%

Im is negligible

Rg = 60 Å

Rg = 38 Å

96%

N-stateN-state dominants dominants

3.4%

IItt is the reference state is the reference state

0.6%

Im is negligible

Rg = 38 Å

99.2%

0.4% 0.4%

When MgWhen Mg2+2+ reaches K reaches KMgMg(I(Itt-to-I-to-Imm), ),

N-stateN-state is over 99% is over 99%

Rg = 38 Å

99.91%

Rg = 60 Å Rg = 46 Å

0.08%0.006%

At high enough Mg2+, Im becomes more stable than It

But none of them populates