1loj
From Proteopedia
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Crystal structure of a Methanobacterial Sm-like archaeal protein (SmAP1) bound to uridine-5'-monophosphate (UMP)
Overview
Intron splicing is a prime example of the many types of RNA processing, catalyzed by small nuclear ribonucleoprotein (snRNP) complexes. Sm, proteins form the cores of most snRNPs, and thus to learn principles of, snRNP assembly we characterized the oligomerization and ligand-binding, properties of Sm-like archaeal proteins (SmAPs) from Pyrobaculum, aerophilum (Pae) and Methanobacterium thermautotrophicum (Mth)., Ultracentrifugation shows that Mth SmAP1 is exclusively heptameric in, solution, whereas Pae SmAP1 forms either disulfide-bonded 14-mers or, sub-heptameric states (depending on the redox potential). By electron, microscopy, we show that Pae and Mth SmAP1 polymerize into bundles of well, ordered fibers that probably form by head-to-tail stacking of heptamers., The crystallographic results reported here corroborate these findings by, showing heptamers and 14-mers of both Mth and Pae SmAP1 in four new, crystal forms. The 1.9 A-resolution structure of Mth SmAP1 bound to, uridine-5'-monophosphate (UMP) reveals conserved ligand-binding sites. The, likely RNA binding site in Mth agrees with that determined for, Archaeoglobus fulgidus (Afu) SmAP1. Finally, we found that both Pae and, Mth SmAP1 gel-shift negatively supercoiled DNA. These results distinguish, SmAPs from eukaryotic Sm proteins and suggest that SmAPs have a generic, single-stranded nucleic acid-binding activity.
About this Structure
1LOJ is a Single protein structure of sequence from Methanothermobacter thermautotrophicus with URI, U and MPD as ligands. Full crystallographic information is available from OCA.
Reference
The oligomerization and ligand-binding properties of Sm-like archaeal proteins (SmAPs)., Mura C, Kozhukhovsky A, Gingery M, Phillips M, Eisenberg D, Protein Sci. 2003 Apr;12(4):832-47. PMID:12649441
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