Crystal Structure of a Variant PAM2 Motif of LARP4B Bound to the MLLE Domain of PABPC1.

Clemens Grimm,Jann-Patrick Pelz,Utz Fischer,Cornelius Schneider,Katrin Schäffler

doi:10.3390/biom10060872

Abstract

Eukaryotic cells determine the protein output of their genetic program by regulating mRNA transcription, localization, translation and turnover rates. This regulation is accomplished by an ensemble of RNA-binding proteins (RBPs) that bind to any given mRNA, thus forming mRNPs. Poly(A) binding proteins (PABPs) are prominent members of virtually all mRNPs that possess poly(A) tails. They serve as multifunctional scaffolds, allowing the recruitment of diverse factors containing a poly(A)-interacting motif (PAM) into mRNPs. We present the crystal structure of the variant PAM motif (termed PAM2w) in the N-terminal part of the positive translation factor LARP4B, which binds to the MLLE domain of the poly(A) binding protein C1 cytoplasmic 1 (PABPC1). The structural analysis, along with mutational studies in vitro and in vivo, uncovered a new mode of interaction between PAM2 motifs and MLLE domains.

Highlights

In higher eukaryotes, posttranscriptional mechanisms contribute significantly to gene expression
Via multiple sequence alignment and a motif search, we discovered a sequence stretch near the N-terminus of LARP4B that was closely related to the PABP interacting motif 2 (PAM2) motif (Figure 1B)
A large variety of different proteins are recruited to messenger ribonucleoprotein particle (mRNP) by virtue of their poly(A)-interacting motif (PAM) motifs

Summary

Introduction

Posttranscriptional mechanisms contribute significantly to gene expression. The mRNA, which is translated into proteins by the ribosomes, has first to undergo several maturation steps, from the primary pre-mRNA transcript to the mature mRNA These include pre mRNA splicing, capping and polyadenylation, which are a prerequisite for the recruitment of additional factors, which contribute to the formation of the functional messenger ribonucleoprotein particle (mRNP). The vast majority of cellular mRNA is polyadenylated on its 3 -end, allowing binding of poly(A) binding proteins (PABPs). These proteins in turn serve as multifunctional scaffolds, enabling the recruitment of diverse factors to mRNPs [1,2]. These proteins contact PABP via a common motif of 12–15 amino acid residues, known as PABP interacting motif 2 (PAM2) [16,17]

Methods

Results

Conclusion