decapping activators in Saccharomyces cerevisiae acts due to direct and indirect interaction between translation repression protein

2. Introduction
M7GpppN-mRNA hydrolase ( DCP2, DCP1 NUDT16, D10 protein, D9
protein, D10 decapping enzyme, decapping enzyme) is an enzyme with
systematic name m7GpppN-mRNA m7GDP phosphohydrolase This enzyme
catalyse the following chemical reaction.
m7G5'ppp5'-mRNA + H2O m7GDP + 5'-phospho-mRNA
Decapping of mRNA is essential in eukaryotic mRNA turnover.

3. TRANSLATION initiation

4. Aim of paper
Before this paper it is known that there are different protein like Pat1,
Scd6, Edc3, and Dhh1 have a role in decapping but there mechanism is
unknown.
To address the mechanism of interactions between these protein to
activate or promote decapping.
1. Is there any direct interaction of these protein in translation
repression?
2. In which state of translation initiation or initiation complex these
proteins affect?
3. Is there any direct interaction between these proteins or Decapping
enzyme?
4. Is full length protein necessary for interaction or not?
5. Is there any coordination of activities between any two or more
proteins?

5. Role of different Protein in TRANSLATION
Scd6, PAT1 domains and Edc1(LsmFDF Domain) act as translation repressor as well as mRNA
stabilizing protein.
Edc3-Yjef-N domain acts in mRNA degradation.

6. Role of Scd6, Pat1, on translation initiation complex
Scd6 and Pat1 act as repressor of translation in PIC (Pre initiation complex) state i.e.
in 48S and 80S state of PIC

7. Interaction between PAT1 domains and Dhh1, Scd6, Xrn1 ,Dcp1, Dcp2
Dhh1, Xrn1,Scd6,Lsm1-7complex and Dcp1 are interacting with PAT1 domains

8. Interaction between PAT1 domains and Dcp2, and PAT1-C domain
Dcp2 shows interaction with PAT1 M and C domains but not with M+C
domains . Because M and C domain shows self interaction.

9. Interaction between domains of Scd6, edc3 with decapping protein (Dcp1, Dcp2)
Dhh1, Edc3,Scd6 are interacting with DCP1/DCP2

10. Role of Edc3, scd6, Dhh1, and domains
of PAT1 in Decapping of mRNA
Domains of PAT1
Edc3 have role in decapping, Dcp2 activity is efficient in presence of Dcp1

12. Model for Transitions Mediated by
Activators of Decappingdiscussion
1. Scd6 acts as translation repressor and activator of
decapping.
2. Pat1 and its domains, Scd6 , Edc3LsmFDF act in mRNA
stability while they also act as decapping activator.
3. Edc3Yjef-N promotes mRNA degradation.
4. Pat1 and its domain have role in decapping .
5. Pat1 acts as a middle man in the activity of Dcp1/Dcp2.
6. Xrn1 is 5’-3’ Exonuclease. But its mechanism of action is
unknown.(means how after decapping it displaces
Dcp1/Dcp2)
7. Dcp1 is necessary for efficient decapping by Dcp2.
8. Its also not known if there are any proteins which help in
decapping and have role in mRNA degradation or act as
activator for degradation by Xrn1.