The PUF Protein Family: Overview on PUF RNA Targets, Biological Functions, and Post Transcriptional Regulation

Abstract

Post-transcriptional regulation of gene expression plays a crucial role in many processes. In cells, it is mediated by diverse RNA-binding proteins. These proteins can influence mRNA stability, translation, and localization. The PUF protein family (Pumilio and FBF) is composed of RNA-binding proteins highly conserved among most eukaryotic organisms. Previous investigations indicated that they could be involved in many processes by binding corresponding motifs in the 3'UTR or by interacting with other proteins. To date, most of the investigations on PUF proteins have been focused on Caenorhabditis elegans, Drosophila melanogaster, and Saccharomyces cerevisiae, while only a few have been conducted on Arabidopsis thaliana. The present article provides an overview of the PUF protein family. It addresses their RNA-binding motifs, biological functions, and post-transcriptional control mechanisms in Caenorhabditis elegans, Drosophila melanogaster, Saccharomyces cerevisiae, and Arabidopsis thaliana. These items of knowledge open onto new investigations into the relevance of PUF proteins in specific plant developmental processes.

Keywords: PUF protein; RNA-binding motifs; plant; post-transcriptional; regulation.

Figure 1

Predictive stick models of the APUM2 (Arabidopsis thaliana Pumilio 2, AT2G29190) PUM-HD (Pumilio homology domain) bound to its target motif. The analysis result based on the research of Francischini and Quaggio [42]. They showed that the PUM-HD of APUM2 bound to the core nucleotides of 5′-UGUANAUA-3′. The each repeat of PUM-HD bound to corresponding nucleotide through Van der Waals force. The protein structure was generated by SWISS-MODEL (https://swissmodel.expasy.org/) [44,45,46,47].

Figure 2

The common model of PUF protein influences mRNA stability. (A) Some genes regulate the expression or binding efficiency of PUF proteins in nucleus and/or in cytoplasm; (B) The PUF protein can bind to the PUF binding motif, which is located in the 3′UTR of target gene, and recruit the CCR4-POP2-NOT complex through interacting with Pop2 (the subunit of CCR4-POP2-NOT complex). The CCR4-POP2-NOT complex acts as a deadenylase in cell. It can affect the mRNA stability by reducing the length of poly(A) tail. Meanwhile, Dhh1p (DExD/H-box ATP-dependent RNA helicase), which can interact with CCR4-POP2-NOT complex, acts on the cap to activate decapping and inhibit translation [60].