DSpace at VNU: Investigation of the possible relationship between mutation at three-dimensional structural level and resistance of culex pipien''s esterases to insecticides

V N U vlOURNAL O F SC IEN C E N Ít

Sci

& Tech

T XIX. N 4. 2003

IN V E S T K 1 A T IO N O F T H E P O S S I B L E R E L A T IO N S H I p BETVVEKN
M U T A T IO N A T TH K E E -D IM E N S IO N A L S T R U C T U R A L L E V E L A N D

KKSISTANCK O F C V L E X P I P I E N S ’S E S T E R A S E S TO
IN S E C T IC ID E S
D a m lỉa c h U u o n g

Center Ị } f lìiotvchnology, Yictnam National Universitv, líanoi
C h ic h e L a u r e n t

ƯMR 504S. Dlỉ /.?. MOXTPKLLIER. Center of Siructural ỉìiochinìiv, CNHS. Framv
1. I n tm d u c tio n
P ro te in

m o d e llin g was p ra ctice d on a specific proble m

vvith

h ig h

h e a lth

im p a ct: the a c q u ire d re sista n cv o f m osquitoes to in se cticid e s. It is k n o w n th a t the

ta rg e t o f coram on or^an oph osph atí* in se cticid e s is esterase. One w a y rrs is ta n c e is
o h ta in e d is tlm n itfh ostorase ovo rexp ressio n (1). H o w cver. p o in t m u ta tio n s have
been noticed in e s te ra s i1 A and B loci o f re s is ta n t cu lcx p ip ie n s . vvhich m ig h t p la v
somo ro le in th e re sista n ce (2).

2. M aterials and m eth o d s
Tho esterases fro m v a rio u s in se c tic id e re s is ta n t and in s e c tirid e se n s ih le culex
p ip ie n s p o p u la tio n s vvrre s tu d ird at th e In s titu t des Sciences de 1 'K v o lu tio n (IS K M ),
U n iv e rs ite des Sciences et T e ch n iq u e s du Languedoc (P rance). O v o ra ll, 28 p ro te in s
have been sequcnced fo r 2 loci A and ỉ i as shovvn belovv.
A lo ci B_loci
6 re s is ta n t and 8 sensible esterases
í> re sista n t and H sensiblt* esterases

Resistant

Sensible

Resistant

Sen sih le

SA 1prot
S A 2prot
SA Iprot
SAõprot
S A7prot
SAHprot

S la b lp ro t

S lab2prot
lỉru g e À
R ru g e lỉ
T ra n sp ro t
Crisse
1ỉeteren
Bleuet

BI
B2
B4
Bf>
B7
B8

S la b l
B rugeA
B rugeB
T ra n s
BSAl
B leutìt
H ete ren
Slab2

11


D a m B a c h Duongy C h ic h e L a u r e n t

12

3. R e s u lts
3. 1. A l i f í n m e n t
3.1.1. A lig n m e n t

T h e a lig n m e n t o f 28 E ste ra se vvas p e ríb rm e d u s in g C L U S T A L W (H ig g in s I) et
a l., 1994, N u c le ic A c id s Res. 22:4673-4680,
a n a ly z e d

u s in g B E L V U

h ttp ://w w w .e b i.a c .u k /c lu s ta lw /) and

(h ttp ://w w w .c g r.k i.s e /c g r/g ro u p s /s o n n h a m m e r/B e lv u .h tm l)

an d S E A V IE W (h ttp ://p b il.u n iv - ly o n l.fr /s o ftw a r e /s e a v ie w .h tm l).
T h re e a lig n m e n t file s in F A S T A fo rm a t w ere p re p a re d
C o E s.íầ sta fo r a ll E ste ra se ; A _ o n ly .fa s ta fo r A lo ci a n d B _ o n ly .fa s ta fo r B_loci
3.1.

2. S electỉo n o f one reference sequence f o r 3 D m o d e lin g

T h e sequence o f S A S p ro t (re s is ta n t) vvas selected because it is th e closest to
se n sib le sequences (o n ly 3 d iffe r e n t re s id u e s in c o m p a ris o n vvith s e n s ib le S la b lp ro t)
3.2. M o d e lin g o f S A 8 p r o t (A _ lo c i)
3. 2.1. S earch f o r a s tru c tu rc il te m p la te
The

sequence S A 8 p ro t vvas s u b m itte d

to th e

In te r n e t s e rv e rs B IO S E R V

(h ttp ://b io s e rv .c b s .c n rs .fr/) an d 3D -P S S M (h ttp ://w w w .s b g .b io .ic .a c .u k /^ 3 d p s s m /) to
fin d th e b e st s tr u c tu r a l te m p la te s fo r m odeling.
T h e fo llo w in g te m p la te s w e re o b ta in e d fo r S A B p ro t
Top 3D -PSSM

1: lm a a ,

2: lq id .

3: le q h .

4: lđ x 4 .

5: lk 4 y

Top P D B -B L A S T

1: lm a a .

2: lm a h ,

3: le 2 b .

4: lc2o,

5; lf8 u

Top T IT O score

1: lm a a ,

2: Iq id ,

3: le q h .

4: k4y

3. 2.2. B u ild i n i t i a l S A S p ro t 3 D m odels
Each te m p la te w as used to b u ilt 3 m odels fo r S A B p ro t (M o d e Ile r4 th ro u g h
B I()S F ]R V ). T h e scores o f the se m odels are as fo llo w s :
P R O S A -II

V E R IF Y -3 D

M o d e ll

M odel2

M odel3

M odel 1

M odel2

M odel3

le q h

- 0,503

• 0,412

- 0,352

0,350

0,348

0.340

1maa

■ 0.377

- 0,232

- 0 ,3 28

0,316

0,331

0,369

Iq id

- 0.482

- 0,500

■ 0,438

0,363

0,331

0.370

lk 4 y

■ 0.420

• 0,300

- 0,392

0,263

0,310

0,310


h ìv e s tig a tio n o f t ỉìc

ỊìtiS H Ìb ic

r c l a t i o t i s h i p b e tiveen .

Vrom nhovi* tiih lr s . t h r h rs t tiio íli‘1

fo r lq e h is M o đ c ll
fo r 1m an is M o di*l3
fo r 1q id

is M o d c l 1

fo r l k ‘1v is M o d e ltỉ
and am ong th e s r m ocỉrls. M o d rl Ị (rom lq id d is p líìy s t h r l)i\st scores. Is w as nam ed
M odel l
3.2.3 C vsteìnvs a n d (iis u lfid e b rid g e s
C vsteines can m ake d isu lp h ick* b rid g e w ith

o th e r c y s te in e s a n d d is u lfid e

briclges are p re se n t in a ll s r liT t r d s tr u c tu r a l te m p la te s . A fre e c y s te in e is aỉso
ohsi*rvi*d in th(* lq id trm p h m *. I)is u lfid e b rid g e s a n d fre e c y s te in e s ob served in th t'
fo u r te m p la te s a n d in th e re s u ltin g m odels are s u n im a riz e d be low :

1maa tem plate
lm a a model

;ỉ bridges (6 CYS) : 69 - 96. 257 - 272. 409 - 529
7 freo ( YS 61. ‘2 96. 306. 328, 362. 436. 508 and 1 b riđ g e 195 • 219

I iịk I tem plate
lqicl model

3 bridges 67 * 94, 254 • 265, 402 • 521 and 1 free CYS 231
7 free CYS 61. 296. 306, 328. 362. 436, 508 and 1 b rid g e 195 - 219

1k i V tem plate
1k-ly model

2 hriclges 87 - 116 and 273 - 284
7 ừee CYS 61. 296, 306, 328. 362. 436, 508 and 1 brid ge 195 - 219

IimịIì template

1 briđ g e 36 • 47. 41 * 57, 09 - 69 and 37 - 159
7 free ỎYS 61. 296, 306, 328, 362, 436 508 and 1 b rid g e 1 9 5 -2 1 9

li*(jh model

It can ỈH* observocl th a t (i) (lis u líid e b rid g e s are n o t f u lly c o n s c rv e d betw een
tc m p la te s and, ( ii) thí* n u m b e r and p o s itio n o f b rid g e s a n d fre e c y s te in e s in the
models is id e n tir n l vvhatever th e tc m p lrite used.
Tho n u m b e r o f fre e cyste in e s in th e m odels is la rg e in c o m p a ris o n to th e
tc m p la te s. A t th is tim < \ we h a vc no e x p la n a tio n fo r th is . I t m a y h a p p e n th a t the

protein is multimuric and that so me disulíide bridges are íormed between
monom ers.
3. 2.4. A n a ly s is a n d o p tim u a tio n o f i n i t i a l S A S p ro í M o d e ll
We used I n s ig h t ll

to vievv a n d a n a ly z e M o d e ll, in c o m p a ris o n

w ith

the

s tru c tu ra l te m p la ti* ( I •I >Ii ID: lq id )
VVe observed an u n u s u a l loop c o n fo rm a tio n fo r re s id u e s ‘2 70 to 290 w as fo u n d
loop. The reason lo r th is is a p p a re n tly due to a too s t r ic t a lig n m e n t. T o get b e tte r
c o n íb rm a tio n s, WI* rrla x i-d a lig n m e n t " u iìa lig n in g " few re s id u e s a t th e C -te rm in a ỉ
loop end as in d ic a tr d bí*low:


D a m B a c h D u o ìig , C h ic h c L a u r e n t

14

M o d e ll L L N E N E

1QI D

VL p - •

I E N R I L

L L N E N E

- - - I E N R I L

F D s I F R

V L p - - - F D s • - -I F R

T h is changes in file m o d e ll.a li was save in to new file : m o d e l2 .a li
F ile s

m o d e l2 .a li

and

m odel2 .top

were

used to

b u ild

M o d e l‘2 th ro u g h

a

s ta n d a lo n e ve rsio n o f M o d e lle r4 ru n n in g on a local SG I w o rk s ta tio n .
The

.tw o

m odels

w ere

(h ttp ://b io s e rv .c b s .c n rs .fr/v a lid .h tm l).

sent
The

to

th e

e v a lu a tio n

E v a ll2 3 D

scores

s e rv e r

p ro v id e

d e ta ile d

in íb rm a tio n fo r each re sid u e and each íra g m e n t o f the m odel.
From th e E v a lu a tio n scores we can see th a t, g e n e ra lly the s tru c tu re o f m odel2
is b e tte r th a n m o d e ll, except fo r re sid ue s 414 * 434. In th is p a rt, e v a lu a tio n scores
o f m o d e ll are bette^r.
T h is p a rt o f M odel2 was m o d ifie d according to M o d e ll. T h e changes in file
m o d e l2 .a li w ere saved in to a new file : m o d e l3 .a li. F ile m o d e l3 .a li an d m odel3.top
w ere usecỉ to b u ild M odel3.
M odel4 was th e o b ta in e d fro m M odel3 by m o đ iíy in g íra g m e n t 62 - 73.
E v a lu a tio n scores o f 4 m odels and te m p la te 1Q ID are show n in th e tablo:
E v a l2 3 D

V e r if y 3D

P ro s a I I

E v T re e

SFE

M odel 1

0,052

0,236

0,037

- 0,365

- 540,6

Model 2

0.051

0,219

0,008

- 0,405

- 529,5

Model 3

0,047

0,219

0,021

- 0,385

- 522,2

M odel 4

0,063

0,210

0,026

- 0,403

- 526,0

1QID

0,111

0,321

0,192

0,290

- 569,2

From th e above ta b le , vve note th a t M odel 4 d is p la y s a good E va l2 3 D score,
but. th a t M o đ e ll is th e b e tte r acco rdin g to a ll o th e r scores.
We th e re ib re selected M odel 1 as%our M odel and m o d iỉie d i t in tw o regions,
v\4iere M odel4 has b e tte r scores (re g io n s 7 1 - 7 8 and 85 - 95). T h e changes in file
m o d e ll.a li w ere saved in to new file : m o delõ .ali. Piles m o d e is .a li; m odelo.top were
used to b u ild M odel5
E v a l 23D

V e r if y 3D

P ro s a I I

E v T re e

SFE

Mođel 1

0.052

0.236

0,037

- 0,365

- 540,6

M odel 4

0.063

0,210

0.026

- 0,403

• 526,0

M o d e l 5/1

0,072

0,241

0,047

- 0,363

- 551,3

Modtj l Õ/2

0,066

0,239

0,036

- 0,366

- 542,4

M ođel 5/3

0,070

0.257

0,045

- 0,369

- 536,1


I m c s t iịỊ o t io n o f t h ỉ ’ po s s ib lc r c i a t io n s h ip betivcen.

15

lí Cỉin he S(*(*n th .it a ll nl 3 v ;m ;itio n s o f mođel 5 have h e tte r scorivs th a n M odel
1 ỉin ri M odel 4. Thi* hest is M n d rl 5/1
K x ỉim in a tio n

n f M ođcl

Ít was nam ed M odel 5.

5 (use

In s ig h t

II)

show s

th a t

a v e ry

bad

loop

eo n ío rm ation (knot) IS p res rn t íor í r a g m e n t 421 • 440. To relax th is region. we
"u n.iliự iK H r tw o r r s u lu e s .

Mocli-I r>
1 Q II)

F s V D s I) T Y N H Y R I V F c D
F N H R A S - - ...................N L V w

Mock-I
F s V I) s D T Y N H Y R I

1QID

F N H R A S ..................... N L -

- - VF c D
vw

T h e changes in file m o đ e ll.a li saved in to new file : m o d e l6 .a li. K iles m o d e l6 .a li:
m o ck'l6 .ỉop werc* u s rđ to In n ld M odel 6.
E v a l2 3 D

V e r if y 3D

P ro s a I I

E v T re e

SFE

Modt'1 5

0,072

0.241

0,047

- 0,363

- 551,3

M o d d
0.046

0.239

0,014

- 0,381

- 548,8

M o d e l 6/2

0,056

0,235

0,045

- 0,389

-5 4 1 ,1

Mocit‘1 (>/M

0,055

0,232

0.032

- 0,376

- 535.7

U s in g I n s ig h t ll we can see th a i in M odel 6 the s tra n g e loop c o n fo rm a tio n has
đisappeaređ. T h is m eans th a t o u r loop re la x a tio n vvas w e ll done. Hovvever, re s u lts
in ta b le show th a t a ll v a ria tio n s o f M odel 6 are w orse th a n M o del 5. O n ly the best o f
them , M o d cl 6/2, is n e a rly close to M o d e l 5 (e specia lly by th e m ost im p o rta n t score,
Prosa II). T h is in d ic a te s th a t we could t r y to im p ro ve a g a in M odel 6/2. Hovvever,
(hu* to tim e lim ita tio n . th e m o d clin g o f S AB prot was stopped.
Krom a ll o f th is . we chose M odel6/2 as o u r M odel 6 fo r S A S p ro t (re s is ta n t in
A_loci). T h is m odel has co rre ct backbone c o n fo rm a tio n and r e la tiv e ly good scores
(P ic .l).
3. 3. M o d e llin Ị Ị o f o P r o te in fr o m B _ lo c i:
A s im ila r s tra te g v was used to b u ild a reference 3D m o deỉ fo r B_loci esterases.
U s in g b e lv u and seaview we chose fro m B_loci B8 (re s is ta n t) fo r m o d e lin g ( It
has h ig h e s t id e n tity score to S A S prot).

The B8 sequence was sent to BIOSERV and 3D-PSSM and the 1QID
s tru c tu ra l te m p la te was selected as p re v io u s ly done fo r A _loci.

B8 w ere b u ilt w ith e ith e r one o f ‘2 ways:


1(3

D a m B a c h D u o n g , C h i chi* L a u r e n t
S ta n d a lo n e M o d e lle r4 : O u tp u t M odel M l/1 . M l/2 , M l/.‘ỉ
B 10S E R V M o d e lle r4 :

O u tp u t M odel M 2/1, M 2/2, M 2/3, M 2/4

A ll models w ere sent to th e E v a ll2 3 D server
E v a l 23D

V e r if y 3D

P ro s a I I

E v T re e

SFE

M o d e l 1/1

0,085

0,228

0,037

- 0,366

- 553,2

M odel 1/2

0.070

0.207

0.025

- 0.394

• f) Ki.6

Model 1/3

0,068

0.219

0.029

• 0.405

- 523.4

M odel 2/1

0,066

0,207

0.021

• 0.378

- 540.7

M odel 2/2

0,051

0.221

0,019

. 0.377

♦ 545.7
1

M odel 2/3

0,079

0,225

0,017

- 0..Ỉ73

• 545, õ

Model 2/4

0,082

0,208

0,036

- 0.399

- 543.0

i
From re s u lts in ta b le , th e be st model is M odel 1/1. U sin g In s i^ h t II vve can see
th a t the model has no a p p a re n t e rro r. From a ll o f th is , we chose M o del 1/1 as o u r
M odel

1 fo r

B8

(re s is ta n t

in

B_loci).

T h is

m odel

has

a

e o rre c t

backbone

c o n fo rm a tio n and re la tiv e ly good scores.
3.4. M o d e l l i n g a n d a n a l y s i s o f a l l P r o t e i n s i n A J o c i

U sing seavievv we checked a ll diíTerences betvveen S A S prot and cach IV o tc in
in A _loci. Then, u s in g S P D lỉV ie vve r, we m utatecỉ the 31) modc*l o f S A S prot to o h ta in
m odels o f a ll o th e r A _loci p ro te in s .
M u ta tio n s

P ro te in
S A 8 p ro t
X
£

■
»«*

S A lp r o t

43. 76. 95. 175. 303. 364. 504. 505. 528

S A 2 p ro t

81. 295. 493, 504

SA4prot

21. 182. 364. 492. 504. 528. 540

S A ỗ p ro t

39. 95, 175, 227. 250, 269. 292. 364. 500. 50-1, 52«. 540

S A 7 p ro t

9. 44. 262. 356. 503, 504

B ru g e A

98. 364. 504. 528

B ru g e B

98, 269, 292. 364, 504. 528

S la b l

177, 504, 540

■c
A
ị

S la b 2

21, 98. 269, 361, 364, 439. 492. 504, 528, 540

C ris s e

95, 152. 175. 250. 292. 337, :i64. 492. 493. 504, 528

05

He te re n
T ra n s p ro t
B le u e t

21. 98. 269. 361. 364. 492. 504. 528
56. 261. 500, 512
21. 98. 492. 504

1


17

Ịn v e s tig a tio n <ìf th c p o ss ib lc r c l a t io n s h ip betiveen.

S in c r

th e

a im

o f w o rk

is "To in v e s tig a te

the p o s s ib lc

re ìa tio n

betỉveen

s tr u c tu r a l m u ta tio n a n d resistance (>f Esterase to in s e c tic id e s ", so o u r in te re s t is
fo cu sin tf in m u ta tio n s , vvhich are observed o n ly in re s is ta n t p ro te in s . For A_loci
the.se m u tỉilio n s ;ire rc»si(liK*s

39» 4^. 44, 76, 81, 182, 227, 295, »303, 356. 503 and

505
A ll m u ta tio n s wt»ro c a re fu lly analyzeci u s in g In s ig h t II. AU m u ta tio n s are
located on th i' suríace ot thí* p ro te in , and re ason ably fa r fro m th e a ctive site. None
o f th e m u ta tio n appears to have a s ig n iíìc a n t im p a c t on s tru c tu re and s ta b ility o f
the p ro te in

It

IS

likely that the mutations observed in the sequences o f the A loci esterases o f

resistani ( ttlcx piptcns arc not responsible for the resistance.

9

39

43

44

O riginal a;i

p- -

p

E

L

Mutated aa

R

s

K

w

s

aa in templíite

N

p

N

M

N

Nitnibct

76

81

182

227

295

303

356

503

505

N

s

p

V

N

V

V

T

p

R

s

1

K

L

1

A

L

s

p

V

T

E

A

E

K.

.. . .

3.5. M o d e llin ịi a n d a n a ly s is o f a l l P r o te in s in B lo c ì
U sing st?aviuw Wí! check a ll d iffe rcn ce s hetw een B8 a n d each o f P ro te in in
B_loci. T h en, u s in g S PD B V ievver, we m u ta te d the 3D m odel o f B8 t. 0 o b ta in models
o f a ll o th e r B J o c i p ro te in s .
M u t a tio n s

P r o te in
B8
H

.8

«9
e
co

BI

20. 38. 98. 188. 213. 222. 257. 301. 335. 376. 461. 476

B2

38, 62. 256. 26(5. 461

B4

20. 38. 51. 98. 100. 127. 188. 222. 297. 376. 461. 476

B5

20. 38. 54. 98. 127. 176. 188. 222. 376. 461. 476. 511.

B7

25. 38. 98. 151. 176. 202. 246. 461

B ru g c A

20. 26. 38. 93. 98, 176, 188, 266, 297, 303, 407. 461. 476, 517

B ru g e B

20, 38. 98. 176, 222. 266, 288, 297, 303, 376, 461. 476. 481. 517

S la b l

25, 38. 169. 176. 262, 459, 461, 500

S la b 2

20. 38. 98, 176. 222. 266, 297, 303, 376. 460, 461. 476

BSA1

20. 38. 54. 93, 98. 188. 239, 266. 297, 376, 461. 476, 492. 497

H e te re n

3. 20, 38, 54. 95, 98. 176, 222. 266, 297. 303, 376, 460, 461, 476, 517

T ra n s

38, 256. 461

B le u e t

25, 38. US9. 176. 297, 320. 375, 461, 476. 517

W ith th e sam e a im o f w o rk as in A _loci, o u r in te re s t is fo c u s in g in m u ta tio n s .
vvhich are h a p p e n in g o n ly in re s is ta n t p ro tc in s . F o r B_loci these m u ta tio n s are
residues 62. 100. 127. 151. 202. 213. 246. 257, 301. 335 and 511.


D a m B a c h I) u o n g 9 C h ic h e L a u r e n t

18

A ll m u tn tio n s w ere c a re fu lly a n nlyzed ưsing ỉn s ig h t I I .

Pic. 1. 3D M odel o f te m p la te

As shovvn below. stĩveral mutations are observgd f'or buried residues. One of
th e m , p o s itio n 213 is p ro x im a l to a ctive site. M o st m u ta tio n s are co n se rva tive .
Hovvever, in p o s itio n

151, an exposed p o la r re sid u e is m u ta te d to a v a lin e . In

p o s itio n 213, a s m a ll b u rie d a la n in e is m u ta te d to a rg in in e . T h e c o rre s p o iu iin g
re sid u e in te m p la te is an a la n in e and s ig n iíic a n t s te ric h in d ra n c e appears in the
a rg in in e m u ta n t. T h is p o in t sh o u ld deserve

fu r th e r stu d ie s (Pic. 2). S im ila rlv . the

m u ta tio n to h is tid in e a t h u rie d p o s itio n 335 deserves fu r t h o r s tu đ ie s re ^ a rd in g

charge complementarities. This position is moreover in close proximity to a loop
re g io n in w h ic h a lig n m e n t betw een the esterase sequence and th e te m p la te is
q u e s tio n a b le (P ic. 3).

P ic. 2. 3D M o del o f B8

Pic. 3 3D M«dt*l ()f B l w ith m u ta tio n s


I n r c s t i g a t i o n o f the possitìle r c l a t io n s h ip betu ccn.
T hrivlnrv.

.'ilthou^h

most

m u t . ỉ t i o n s observi»(l in t h e

s r < | u t * r u ' í as C ) f t h e

|{ l o c i

r s t r r a s t s u f n s is ia n t ( u l r \ pipim.N ỉip p e a r u n re la trd to the ri/s is ta n c e phcnom eno n.
tlm -r

niutỉitÌIHÌS

im p a ct.

1 'iir th iT

;it

positinn

l ‘) l .

m v o s ti^ ;n in n

21M

w ill

and

3ÍỈ5

ni.iv

h.ivc

structurnl

tu* necessỉirv to mon* c*arc*fully ỉtn iilv /.c

the

p o .s s iM r im p í ỉc t ol t h r s c t l u v r m u t ỉ i t i o n s .

N u m b c *r
—
62
100
127
151
•202

O r ií í in a l aa

M u ta te d aa

T
L

s
F

V
K

1

1

V

Ạ

R

0

i>

A
E

R

.___ 213
•JK i

257
301

Q
511

1

.

C om m ent
exposed
s

expost/d
T
h u rie d
A
exposcđ. hydrophobic
G
b u rie d
L
b u r i í đ , s t e r ic h in d r a n c e
A
exposed
N
E
exposed
exposecl
s
h u r ie d , a lig n m e n t
h u ric d
I ..........J

aa in te m p la te

A

.L.

H
V.

_ _

4. C o n clu sio n
1.

28

th re e -d im e n s io n a l

m odels

of

in s e c tic id e

sensihle

and

in s e c tic id e

rc s is ta n t cu le x p ip ie n s esterases vvere b u ilt (11 fo r A _loci and

14 fo r

B _loci).
2.

A ll o f m u ta tio n s in A _loci. w h ic h are speciíìc to re s is ta n t p o p u la tio n s
a p pea red in s itfn ific a n t and p ro b a b ly do not p la y a n v rolí* in re s is ta n c e o f

Culex pipiens to insecticides.
•i.

M ost m u ta tio n s in IV loci also appeared u n re la te d to insecticide re s is ta n c c ,
except m u ta tio n s in p o sitio n s 151, 213 and .‘M õ ( B l) .

These m u tỉitio n s

m ig h t havt* s ig n iíìc a n t im pa ct on s tru c tu re o r s ta b ilit v o f th e este rase in
(he re s is ta n t p o p u lỉitio n . M ore d e ta ile d discussion o f th e po ssible ro le o f
theso m u ta tio n s in re sistíin ce o f C ulex p ip ie n s to in s e c tic id e s s h o u ld avvait
fu r th e r in v e s tig a tio n s .
T h is w o rk

vvas su p p o rte d by

P r o je c t

2002 N °

12735 C N R S

-

CNST

(E n z y m e a n d P r o t e in T e c h n o lo g y L a b . C B T , V N U )
R e fe re n c e s
1

Raymoncl L*t n I . A n ovc»rvit*w ()f t h e e vo l u t i o n o f o v e r p r o d u c e d e s t e r as e s in

t h e m o sq u i t o

Culex p i p i e n s . P hil T r a n s R Soc Lond B, 353(1998), pp 1707* 1711.
2.

VValsh et al. ld ikn tific;itio n and <*haracterization of m utations m housíly (Musca
domustica) achetvlcholinosterase involved in insecticide resistance.
Btochem J
3 5 9 ( 2 0 0 1 ) . p p 175* 1 S I


D a m B a c h D u o n g , C h ic h e L a u r e n t

20

ĨA P CH) K H O A H O C O H Q G H N , KH TN & CN,

T X IX , N 04. 2 0 0 3 __________

N G H IÊ N CỬU S ơ BỘ K H Ả NĂN G L IÊ N Q U A N G IỬ A Đ Ộ T B IÊ N
CÂU T R Ú C K H Ô N G G IA N CỦ A P H Ả N T Ử E S T E R A S E S VÀ T ÍN H
K H Á N G T H U Ố C T R Ừ CÔN T R Ù N G ở LOÀI C U L E X P I P IÉ N
Đ à m B ạch Dương
T ru n g tám Công nghệ S in h học, D ạ i học Quốc g ia H à N ộ i
C h ic h e L a u r e n t
T ru n g tám cấu trú c sin h hoá, U M R 5048, D R 13, M o n tp e llie r, CNRS, France
Loài m uỗi C ulex p ip ie n s có khà nãng kh á n g th u ô c trừ côn tr ù n g nhò vào sự
th a v đổi tín h c h ấ t của p ro te in E sterase. Việc n g h iê n cứu k h ả năng liê n quan giữa

các đột biến cấu trú c khôn g ia n của phân tử này và tín h k h á n g th u ố c đã được tiế n
h à n h tạ i T ru n g tâ m cấu trú c s in h hóa M o n tp e llie r (P háp).
M ô th ìn h phân tử 3D của 28 p ro te in thuộc nhóm E sterase đã được xây dựng.
Qua phân tíc h các độ t biến cấu trú c , có th ể k ế t lu ậ n rằ n g m ọi độ t b iế n tạ i nhóm
A_loei đều khô ng gây ảnh hương đến tín h c h ấ t của p ro te in . Đ iê u này có nghía là
nhữ ng đột biến này kh ô n g liê n qu an đến tín h kh á n g th u ố c của C ulex p ỉp ie n s.
Đôi với nhóm B J o c i, có 3 độ t biến cấu trú c tạ i các điếm 151, 213 và 335 có th ể
gây ra sự th a y (tối tin h c h ấ t cua p ro te in . T u y vậy, việc tìm ra câu trả lới cu (Vi cùng
vể sự liê n quan giữa nhừ ng đột biên cấu trú c n à y với tín h k h a n g s th u ố c trừ côn
trù n g đòi hỏi p h ải tiế n hà nh th ê m các nghiên cứu khá c nữa.