TY - JOUR
T1 - A Novel Function of the MA-3 Domains in Transformation and Translation Suppressor Pdcd4 Is Essential for Its Binding to Eukaryotic Translation Initiation Factor 4A
AU - Yang, Hsin Sheng
AU - Cho, Myung Haing
AU - Zakowicz, Halina
AU - Hegamyer, Glenn
AU - Sonenberg, Nahum
AU - Colburn, Nancy H.
PY - 2004/5
Y1 - 2004/5
N2 - An α-helical MA-3 domain appears in several translation initiation factors, including human eukaryotic translation initiation factor 4G (eIF4G) and DAP-5/NAT1/p97, as well as in the tumor suppressor Pdcd4. The function of the MA-3 domain is, however, unknown. C-terminal eIF4G (eIG4Gc) contains an MA-3 domain that is located within the eIF4A-binding region, suggesting a role for eIF4A binding. Interestingly, C-terminal DAP-5/NAT1/p97 contains an MA-3 domain, but it does not bind to eIF4A. Mutation of amino acid residues conserved between Pdcd4 and eIF4Gc but not in DAP-5/NAT1/p97 to the amino acid residues found in the DAP-5/NAT1/p97 indicates that some of these amino acid residues within the MA-3 domain are critical for eIF4A-binding activity. Six Pdcd4 mutants (Pdcd4E249K, Pdcd4D253A, Pdcd4 D414K, Pdcd4D418A, Pdcd4E249K,D414K, and Pdcd4D253A,D418A) lost >90% eIF4A-binding activity. Mutation of the corresponding amino acid residues in the eIF4Gc also produced similar results, as seen for Pdcd4. These results demonstrate that the MA-3 domain is important for eIF4A binding and explain the ability of Pdcd4 or eIF4Gc but not DAP-5/NAT1/p97 to bind to eIF4A. Competition experiments indicate that Pdcd4 prevents ca. 60 to 70% of eIF4A binding to eIF4Gc at a Pdcd4/eIF4A ratio of 1:1, but mutants Pdcd4D253A and Pdcd4D253A,D418A do not. Translation of stem-loop structured mRNA is susceptible to inhibition by wild-type Pdcd4 but not by Pdcd4D253A, Pdcd4D418A, or Pdcd4D235A,D418A. Together, these results indicate that not only binding to eIF4A but also prevention of eIF4A binding to the MA-3 domain of eIF4Gc contributes to the mechanism by which Pdcd4 inhibits translation.
AB - An α-helical MA-3 domain appears in several translation initiation factors, including human eukaryotic translation initiation factor 4G (eIF4G) and DAP-5/NAT1/p97, as well as in the tumor suppressor Pdcd4. The function of the MA-3 domain is, however, unknown. C-terminal eIF4G (eIG4Gc) contains an MA-3 domain that is located within the eIF4A-binding region, suggesting a role for eIF4A binding. Interestingly, C-terminal DAP-5/NAT1/p97 contains an MA-3 domain, but it does not bind to eIF4A. Mutation of amino acid residues conserved between Pdcd4 and eIF4Gc but not in DAP-5/NAT1/p97 to the amino acid residues found in the DAP-5/NAT1/p97 indicates that some of these amino acid residues within the MA-3 domain are critical for eIF4A-binding activity. Six Pdcd4 mutants (Pdcd4E249K, Pdcd4D253A, Pdcd4 D414K, Pdcd4D418A, Pdcd4E249K,D414K, and Pdcd4D253A,D418A) lost >90% eIF4A-binding activity. Mutation of the corresponding amino acid residues in the eIF4Gc also produced similar results, as seen for Pdcd4. These results demonstrate that the MA-3 domain is important for eIF4A binding and explain the ability of Pdcd4 or eIF4Gc but not DAP-5/NAT1/p97 to bind to eIF4A. Competition experiments indicate that Pdcd4 prevents ca. 60 to 70% of eIF4A binding to eIF4Gc at a Pdcd4/eIF4A ratio of 1:1, but mutants Pdcd4D253A and Pdcd4D253A,D418A do not. Translation of stem-loop structured mRNA is susceptible to inhibition by wild-type Pdcd4 but not by Pdcd4D253A, Pdcd4D418A, or Pdcd4D235A,D418A. Together, these results indicate that not only binding to eIF4A but also prevention of eIF4A binding to the MA-3 domain of eIF4Gc contributes to the mechanism by which Pdcd4 inhibits translation.
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U2 - 10.1128/MCB.24.9.3894-3906.2004
DO - 10.1128/MCB.24.9.3894-3906.2004
M3 - Article
C2 - 15082783
AN - SCOPUS:1942453838
VL - 24
SP - 3894
EP - 3906
IS - 9
ER -