LSM2

LSM2 (PF3D7_0520300) is an Sm-like protein of P. falciparum that has been placed within the mRNA decay machinery through its co-purification with PfDOZI-associated processing body (PB)-like mRNPs in schizonts (PMID:38702310). In this context LSM2 co-immunoprecipitates with PfDOZI alongside decapping enzymes (DCP2, DCP1), other LSm proteins (LSm1-4, LSm7), and the deadenylase/CCR4-NOT-associated components NOT1, CAF1 and CAF40, and is relatively more abundant in schizont-stage PfDOZI complexes than core stress granule components, consistent with a role in mRNA decay (PMID:38702310). LSM2 has also been detected in the experimentally determined core nuclear proteome of P. falciparum (PMID:23181666). Beyond this membership in the PfDOZI mRNP and its nuclear detection, no direct functional experiments have been performed on LSM2 itself in the available corpus.

1. 2012 Low

   Establishing where LSM2 resides was the first step toward assigning it a cellular role; detection in the isolated nuclear fraction placed the protein in the nucleus.

   Evidence high-accuracy mass spectrometry of isolated nuclear fractions with bioinformatic analysis, validated with transgenic lines, in P. falciparum

   PMID:23181666

   Open questions at the time

   • Large-scale proteomic inventory with no functional experiment on LSM2 specifically
   • Does not resolve subnuclear localization or associated complexes
   • Nuclear detection is not reconciled with the later cytoplasmic mRNP association
2. 2024 Medium

   Whether LSM2 participates in mRNA metabolism was addressed by showing it is a component of PfDOZI-associated PB-like mRNPs enriched for decay machinery, implicating it in mRNA decay rather than storage.

   Evidence GFP-trap immunoprecipitation of PfDOZI::GFP followed by mass spectrometry in P. falciparum schizonts

   PMID:38702310

   Open questions at the time

   • Single Co-IP/MS experiment with no reciprocal pull-down or direct functional validation of LSM2
   • Does not establish which RNAs or complex subunits LSM2 directly contacts
   • No knockout, knockdown, or biochemical reconstitution of LSM2 function

• It remains unknown whether LSM2 has any function beyond its membership in the PfDOZI mRNP, and no direct biochemical or genetic role has been defined for the protein.
• No genetic ablation or phenotype for LSM2
• No demonstration of direct RNA binding or Sm-like ring assembly by LSM2
• No resolution of how nuclear detection relates to cytoplasmic mRNP association