Sandbox WWC7: Difference between revisions

Pentatricopeptide repeat (PPR) proteins are a family of sequence specific RNA-binding proteins which participate in organelle RNA metabolism. Although the mechanisms of RNA binding and the functions of PPR proteins are not fully understood, PPR proteins are thought to assist in RNA editing,<ref>PMID:17015439</ref> translation,<ref name = "translation">DOI:10.1073/pnas.1012076108</ref> and organelle biogenesis.<ref>PMID:15269332</ref> While PPR proteins are found in many eukaryotes, they make up the majority of RNA-binding factors in plant organelles. PPR proteins are characterized by a series of tandem-repeat amino acid consensus sequences which form α-helix <scene name='69/696301/Hairpins/1'>hairpins</scene>. These hairpin structures accumulate to form an <scene name='69/696301/Monomer/1'>α-solenoid tertiary structure</scene> (blue to red from N terminus to C terminus). PPR proteins belong to one of two classes: P-class and PLS-class, with the P-class containing 35 amino acid repeats and the PLS-class containing 31-36 amino acid repeats. PPR10 (shown to the right dimerized and bound to RNA) is a well-characterized P-class PPR protein found in the chloroplast of ''Zea mays'' which is often used as a model PPR protein.<ref name = "translation"/>

Recent advances in programmable site-directed DNA-binding proteins (such as CRISPR-Cas9) have shown incredible potential for medical, agricultural, and scientific application. As a result, it is not surprising that researchers are attempting to develop similar protein-based tools for programmable RNA binding. Unfortunately, few RNA-binding proteins act in a manner which is predictable enough to facilitate convenient RNA manipulation. PPR proteins hold great promise for this application. As described previously, PPR proteins bind RNA nucleotides in a specific and predictable manner, so researchers are attempting to develop custom-made PPR proteins for use in manipulative gene expression experiments.