3. 1.What is a Ribozyme?
1.What
Ribozymes are true enzymes.
enzymes.
A ribozyme is an RNA molecule
(分子) that is capable
capable(能力)
of catalyzing (催化)a chemical
a
reaction.
NOT PROTEIN
PROTEIN(蛋白)
4. First Ribozyme discovered
上世纪80 80
80年代,美国科罗拉多大学博尔德分校的
Thomas Cech(The intron in the pre-rRNA of Tetrahemena is
self-spliced 和美国耶鲁大学的Sidnery Altan(The M1
self-spliced) Sidnery Altan The
RNA in ribonuclease P is catalytic 各自独立地发现RNA
catalytic) RNA
RNA具有
生物催化功能.从而改变了生物催比剂的传统概念。
.
1989 Nobel Prize
In Chemistry
Sid Altman Tom Cech
6. How many ribozyme ?
the hammerhead ribozyme (plant virus)
锤头状核酶(来源:植物病毒)
- the hairpin ribozyme (plan virus)
发夹状核酶
- hepatitis delta ribozyme (human virus)
丁型肝炎核酶(来源:人类病毒)
- neurospora VS ribozyme (mitochondrial RNA)
孢VS
VS
VS核酶(来源:线粒体RNA RNA
RNA)
- group I and group II intron ribozyme (rRNA and mt RNA)
内含子I和II
I II
II核酶(来源:rRNA MT RNA
rRNA
rRNA和MT RNA)
- RNAse P (tRNA maturation)
核糖核酸酶P(来源:tRNA
P tRNA
tRNA的成熟)
- Ribosome (translation)
核糖体(翻译)
- Spliceosome (splicing)
剪接 (拼接)
7. 天然核酶及核糖酶
Ribozym Sequenced Size (nt) Activity Source
(核酶) (测序) (大小) (功能) (来源)
Group I intron >1’500
>1’ 210 self-splicing via 3’-OH
3’ eukayotic pre-mRNA,
of G; transesterification organelles, few bacteria
Group II intron >700 500 self-splicing via 3’-OH
3’ organelles, few prokaryotes
of A; transesterification
Hammerhead 11 40 self-cleavage via plant viruses
Hepatitis delta virus 2 90 transesterification hepatitis B virus (RNAgen.)
Hairpin 1 70 (2’,3’-cyclic phosphate)
(2’ ,3’ satellite RNA of plant virus
RNAse P >500 300 pre-tRNA processing prokaryotes and organelles
via hydrolysis (3 ’-OH)
(3’ of eukaryotes
Spliceosome pre-mRNA splicing via eukaryotic pre-mRNAs
(U2 + U6 snRNAs) 70; 50 180; 100 ransesterification (3 ’OH)
(3’
Ribosome >900 2’600
2’ peptidyl transfer (amide) prokaryotes and eukaryotes
(23S rRNA)
Naturally occurring ribozymes and ribonucleoprotein enzymes (2002)
peptidyl transfer (amide)
(amide)转移肽(酰胺) self-splicing
self-splicing自我剪接 self-cleavage
self-cleavage自我裂解 2’,3’-cyclic phosphate 2' 3' -
,3’ 2',3' -环磷酸
transesterification酯交换 prokaryotes and eukaryotes 原核生物和真核生物
transesterification
pre-tRNA processing via hydrolysis (3 ’-OH) 处理经水解的前氨酰- tRNA 3' - OH
(3’ - tRNA(3' OH)
8. 3.结构(Structure )
3.
consider...
As with proteins, we consider...
Primary: GGCCGAACUGGUA
一级
Secondary
二级:
Tertiary
三级:
9. 3.1 Primary Structure
Structure一级结构
ribonucleotides核苷酸 (base
Limited to ribonucleotides base碱基 + ribose
ribose核糖 + phosphate
phosphate磷酸):
Common Bases: N O N O
常见碱基 N
N
N
N N N
N N N N N N O N O
A G C U
Uncommon Bases: O O
罕见碱基 N N
N
N
O N N
Pseudouridine Inosine
假尿苷 肌苷 etc...
10. 3.2 Secondary Structure
Structure(二级结构)
Watson-Crick Base Pairing Helix Formation
沃森-克里克碱基配对
- 螺旋形成
B-DNA A-DNA RNA
RNA usually assumes
A-form helices…
helices…
DNA
DNA常常假设A- A-
A-型螺旋
Small pore along helical axis
沿螺旋轴形成个小孔
“Rungs” stack obliquely to axis
Rungs”
阶梯式的斜上升的中心轴
11. I
-5 -5
CU G
3′ B YB
50
5′ V GV
GA A
10
20 C
A
G U
U
A A
H 40
A A
A
C
30
2-2
发卡型核酶二级结构
12.
13. Secondary Structure
Structure(二级结构)
Conserved base-pairing interactions result in...
保守的碱基配对相互作用的导致:
• Three “stem” regions
stem”
三个结构域
• Uridine-containing turn
旋转而封闭的尿苷
• An “augmenting helix”
helix”
joining stems II and III
结构域II 与 III
II III连接形成的增强螺旋结构
14. Ribozyme vs. tRNAPhe
核酶 苯丙氨酸tRNA
tRNA
folding
folding折叠
15. The hammerhead ribozyme ( )
(锤头状核酶)
- discovered in small RNA satellites of small viruses (1986)
是小病毒携带的小的RNA RNA
- replication by rolling circle mechanism
通过不断循环机制进行复制折叠
Secondary structure
16. RNAse P(核糖核酸酶P) is a ribozyme
P
RNAse P cleaves the 5’ end of pre-
5’
tRNAs
(核糖核酸酶P切割5' P 5' tRNA
5'前体tRNAtRNA的末段)
It is composed of 12 kDa P protein and
about 400 nt long RNA
(它是由12 kDa
12 kDa蛋白质和长约400 400
400元的RNARNA
RNA组
成)
The catalytic activity lies entirely within
RNA part
(催化活性中心位于RNA RNA
RNA上)
17. RNAse P(核糖核酸酶P) is a ribozyme
P
Enzyme is efficient without P protein but
in high salt conditions
(在高的盐条件,酶在没有P蛋白时还是有活性 P
的)
P protein or high salt is thought to
screen the repulsive electrostatic
interactions between RNAse P RNA and
substrate pre-tRNA
(P 蛋白质或高盐被认为是核糖核酸酶P RNA P
与前体tRNAtRNA
tRNA表面之间静电排斥反应的屏障。
38. 举例:Engineered allosteric ribozymes as biosensors
Engineered
(具有生物传感器功能的变构核酶)
a. ATP-sensing aptamer + self-cleaving
ribozyme.
ribozyme.
ATP传感适体+自我切割核酶。
ATP +
b. This variant favors ADP binding 100-fold
overATP.
overATP.
这种变异使对ATP ATP
ATP的亲和力是ADP 100
ADP 100倍。
ADP的100
c. Can be used as an in vitro sensor for
enzyme activity (or for enzyme inhibition).
inhibition).
用作体外传感器的酶激动剂(或酶的抑制剂)。