2L52: Solution structure of the small archaeal modifier protein 1 (SAMP1) from Methanosarcina acetivorans

In archaea, two ubiquitin-like small archaeal modifier protein (SAMPs) were recently shown to be conjugated to proteins in vivo. SAMPs display homology to bacterial MoaD sulfur transfer proteins and eukaryotic ubiquitin-like proteins, and they share with them the conserved C-terminal glycine-glycine motif. Here, we report the solution structure of SAMP1 from Methanosarcina acetivorans and the activation of SAMPs by an archaeal protein with homology to eukaryotic E1 enzymes. Our results show that SAMP1 possesses a beta-grasp fold and that its hydrophobic and electrostatic surface features are similar to those of MoaD. M. acetivorans SAMP1 exhibits an extensive flexible surface loop between helix-2 and the third strand of the beta-sheet, which contributes to an elongated surface groove that is not observed in bacterial ubiquitin homologues and many other SAMPs. We provide in vitro biochemical evidence that SAMPs are activated in an ATP-dependent manner by an E1-like enzyme that we have termed E1-like SAMP activator (ELSA). We show that activation occurs by formation of a mixed anhydride (adenylate) at the SAMP C-terminus and is detectable by SDS-PAGE and electrospray ionization mass spectrometry.
PDB ID: 2L52Download
MMDB ID: 88421
PDB Deposition Date: 2010/10/24
Updated in MMDB: 2018/05
Experimental Method:
solution nmr
Source Organism:
Similar Structures:
Biological Unit for 2L52: monomeric; determined by author
Molecular Components in 2L52
Label Count Molecule
Protein (1 molecule)
Methanosarcina Acetivorans Samp1 Homolog
Molecule annotation
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