5AF0

MAEL domain from Bombyx mori Maelstrom

Summary for 5AF0

• Entry DOI: 10.2210/pdb5af0/pdb
• Descriptor: MAELSTROM, ZINC ION (3 entities in total)
• Functional Keywords: unknown protein, mael, pirna, ribonuclease, fusion protein, piwi
• Biological source: BOMBYX MORI (SILK MOTH); More
• Total number of polymer chains: 4
• Total formula weight: 119657.54

Authors

Chen, K.,Campbell, E.,Pandey, R.R.,Yang, Z.,McCarthy, A.A.,Pillai, R.S. (deposition date: 2015-01-13, release date: 2015-04-01, Last modification date: 2024-05-08)

Primary citation

Chen, K.,Campbell, E.,Pandey, R.R.,Yang, Z.,Mccarthy, A.A.,Pillai, R.S.
Metazoan Maelstrom is an RNA-Binding Protein that Has Evolved from an Ancient Nuclease Active in Protists.
RNA, 21:833-, 2015

PubMed Abstract: Piwi-interacting RNAs (piRNAs) guide Piwi argonautes to their transposon targets for silencing. The highly conserved protein Maelstrom is linked to both piRNA biogenesis and effector roles in this pathway. One defining feature of Maelstrom is the predicted MAEL domain of unknown molecular function. Here, we present the first crystal structure of the MAEL domain from Bombyx Maelstrom, which reveals a nuclease fold. The overall architecture resembles that found in Mg(2+)- or Mn(2+)-dependent DEDD nucleases, but a clear distinguishing feature is the presence of a structural Zn(2+) ion coordinated by the conserved ECHC residues. Strikingly, metazoan Maelstrom orthologs across the animal kingdom lack the catalytic DEDD residues, and as we show for Bombyx Maelstrom are inactive as nucleases. However, a MAEL domain-containing protein from amoeba having both sequence motifs (DEDD and ECHC) is robustly active as an exoribonuclease. Finally, we show that the MAEL domain of Bombyx Maelstrom displays a strong affinity for single-stranded RNAs. Our studies suggest that the ancient MAEL nuclease domain evolved to function as an RNA-binding module in metazoan Maelstrom.

PubMed: 25778731
DOI: 10.1261/RNA.049437.114

Experimental method

X-RAY DIFFRACTION (2.401 Å)