The RING domains of the promyelocytic leukemia protein PML and the arenaviral protein Z repress translation by directly inhibiting translation initiation factor eIF4E.
The promyelocytic leukemia protein (PML) is a mammalian regulator of cell growth which is characteristically disrupted in acute promyelocytic leukemia and by a variety of viruses. PML contains a RING domain which is required for its growth-suppressive and antiviral properties. Although normally nuclear, in certain pathogenic conditions, including arenaviral infection, PML is relocated to the cytoplasm, where its functions are poorly understood. Here, we observe that PML and arenavirus protein Z use regions around the first zinc-binding site of their respective RING domains to directly interact, with sub-micromolar affinity, with the dorsal surface of translation initiation factor eIF4E, representing a novel mode of eIF4E recognition. PML and Z profoundly reduce the affinity of eIF4E for its substrate, the 5' 7-methyl guanosine cap of mRNA, by over 100-fold. Association with the dorsal surface of eIF4E and direct antagonism of mRNA cap binding by PML and Z lead to direct inhibition of translation. These activities of the RING domains of PML and Z do not involve ubiquitin-mediated protein degradation, in contrast to many RINGs which have been observed to do so. Although PML and Z have well characterized physiological functions in regulation of growth and apoptosis, this work establishes the first discrete biochemical mechanism which underlies the biological activities of their RING domains. Thus, we establish PML and Z as translational repressors, with potential contributions to the pathogenesis of acute promyelocytic leukemia and variety of viral infections.
Kentsis
A
A
Department of Physiology & Biophysics, Mount Sinai School of Medicine, New York, NY 10029, USA.
Dwyer
E C
EC
Perez
J M
JM
Sharma
M
M
Chen
A
A
Pan
Z Q
ZQ
Borden
K L
KL
D018050:Arenavirus / Q000737:chemistry*; D001665:Binding Sites; D002942:Circular Dichroism; D039561:Eukaryotic Initiation Factor-4E; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D008025:Ligases / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins; D010448:Peptide Initiation Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000071156:Promyelocytic Leukemia Protein; D011485:Protein Binding; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012315:RNA Caps / Q000096:biosynthesis / Q000378:metabolism; D020871:RNA Stability; D021241:Spectrometry, Mass, Electrospray Ionization; D013816:Thermodynamics; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism
D039561:Eukaryotic Initiation Factor-4E; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010448:Peptide Initiation Factors; D000071156:Promyelocytic Leukemia Protein; D012315:RNA Caps; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D014452:Ubiquitins; D014764:Viral Proteins; C070576:PML protein, human; D044767:Ubiquitin-Protein Ligases; D008025:Ligases; D015032:Zinc