1. Structure and Function Laura Martin
HIV Integrase (IN)
Structure and Function
Laura Martin

2. What is Integrase? A part of Pre- Integration Complex (PIC)
Integrates viral DNA into host, essential to replication cycle of HIV
Without integrase viral DNA could not get into host genome
Carries out cutting and joining events to integrate HIV DNA (happens within the nucleus)

4. Integrase has NLS ?! - no nuclear localization without it -we do not know nuclear import pathway (not the expected pathway)
Reverse
transcription
Pre-Integration
Complex
Nuclear
import
Integration

5. Mechanism 1st step- 3’ end processing 2nd step- DNA strand transfer
3rd step- Repair or 5’ end joining
(not by integrase)
Little site specificity

6. HIV Integration Target DNA Viral DNA Provirus (2) Strand Transfer5’ AC CA
(1) 3’-end processing
(2) Strand Transfer
HO-
-OH
Provirus
(3) 5’-end joining

7. Structure
Three domains- the catalytic core, the C- terminal and N-terminal domains
Catalytic core – contains active site responsible for catalysis of integration reaction
C- terminal- binds both viral and host DNA
N- terminal- unknown, but has zinc binding motif suggesting nucleic acid interaction7

8. HIV Integrase N CORE C (1-49) (50-212) (213-288) D-X(39-58)-D-X35-E
H12 H16
C40 C43
D64
D116
E152 N
CORE C
(1-49)
(50-212)
( )

9. Arrangement of Domains
Spatial arrangement unknown
Flexibility is linkage between core and C- Terminal

10. HIV Integrase
N-terminus
Core
C-terminus

11. Structure of HIV Integrase
Full length enzyme (1-288 a.a)
Catalytic core ( a.a)
C-terminal domain ( a.a)
N-terminal domain (1-51 a.a)

12. Structure of Catalytic Core Domain
Responsible for catalysis
Central 5 stranded Beta- sheet with six surrounding helices
-3 highly conserved acidic residues (D64- Asp, D116-Asp, E152- Glu)

13. Primary Structure of the Catalytic Domain

14. The N-terminal Domain Bundle of 3 alpha helices with SH3 fold
-Conserved HHCC motif – zinc finger
-His and Cys residues that bind zinc
-Probably functions in
multimerization and stimulates catalysis
-DNA Binding

15. C- Terminal Domain -Binds DNA nonspecifically -Dimer
-Hydrophobic interactions
between two, 3 stranded
beta sheets
-Each monomer is
constructed of 5 stranded
beta-barrel

16. Why HIV Integrase is important!
Total: 34 – 46 million
Western Europe –
North Africa & Middle East –
Sub-Saharan Africa
25.0 – 28.2 million
Eastern Europe & Central Asia
1.2 – 1.8 million
South
& South-East Asia
4.6 – 8.2 million
Australia
& New Zealand –
North America
– 1.2 million
Caribbean –
Latin America
1.3 – 1.9 million
East Asia & Pacific
– 1.3 million

17. Sources King, Peter Powerpoint: HIV, AIDS, Integrase and You
Pieribone, Ph.d, Vincent. "HIV Integrase: A New Therapeutic Target." Treatment Issues (1995). 8 Nov <
Robert, Cragie. "HIV Integrase, a Brief Overview from Chemistry to Therapeutics." Journal of Biological Chemistry (2001). 8 Nov <
Subhendu Chakraborti Power Point presentation: HIV Integrase Last but not least
Walsh, Matthew B., and Marcey David. "HIV- 1 Integrase The Catalytic Core Domain and Minimal DNA Binding Domain." (2001). 8 Nov <