SNAP output for PDB entry 2n7c [SNAP web server]

PDB-id

2n7c; SNAP-derived features in text and JSON formats; DNAproDB

Class

RNA binding protein-RNA

Method

NMR

Summary

Solution structure of plasmodium falciparum sr1-rrm1 in complex with acauca RNA

Reference

Ganguly AK, Verma G, Bhavesh NS (2019): "The N-terminal RNA Recognition Motif of PfSR1 Confers Semi-specificity for Pyrimidines during RNA Recognition." J. Mol. Biol., 431, 498-510. doi: 10.1016/j.jmb.2018.11.020.

Abstract

Alternative splicing confers a complexity to the mRNA landscape of apicomplexans, resulting in a high proteomic diversity. The Plasmodium falciparum Ser/Arg-rich protein 1 (PfSR1) is the first protein to be confirmed as an alternative splicing factor in this class of parasitic protists [1]. A recent study [2] showed a purine bias in RNA binding among cognate RNA substrates of PfSR1. Here, we have investigated the role played by the amino-terminal RNA recognition motif (RRM1) of PfSR1 from the solution structure of its complex with ACAUCA RNA hexamer to understand how its mechanism of RNA recognition compares to human orthologs and to the C-terminal RRM. RNA binding by RRM1 is mediated through specific recognition of a cytosine base situated 5' of one or more pyrimidine bases by a conserved tyrosine residue on β₁ and a glutamate residue on the β₄ strand. Affinity is conferred through insertion of a 3' pyrimidine into a positively charged pocket. Retention of fast dynamics and ITC binding constants indicate the complex to be of moderate affinity. Using calorimetry and mapping of NMR chemical shift perturbations, we have also ascertained the purine preference of PfSR1 to be a property of the carboxy terminal pseudo-RRM (RRM2), which binds RNA non-canonically and with greater affinity compared to RRM1. Our findings show conclusive evidence of complementary RNA sequence recognition by the two RRMs, which may potentially aid PfSR1 in binding RNA with a high sequence specificity.