Genome-Wide Analysis of Arabidopsis Pentatricopeptide Repeat Proteins Reveals Their Essential Role in Organelle Biogenesis[W]

TLDR

The Arabidopsis thaliana genome contains thousands of genes, among them a large, poorly understood family of pentatricopeptide repeat proteins. The study aims to comprehensively characterize the Arabidopsis PPR family. The authors performed a detailed bioinformatic survey of 441 PPR proteins and integrated expression, localization, and functional data from microarrays, fluorescent protein fusions, insertion mutants, and RNA binding assays. The analyses reveal that PPR proteins are constitutively and often essential for mitochondria and chloroplast function, likely through binding organellar transcripts, and they substantially extend prior sparse observations from single‑mutant studies in other species.

Abstract

Abstract The complete sequence of the Arabidopsis thaliana genome revealed thousands of previously unsuspected genes, many of which cannot be ascribed even putative functions. One of the largest and most enigmatic gene families discovered in this way is characterized by tandem arrays of pentatricopeptide repeats (PPRs). We describe a detailed bioinformatic analysis of 441 members of the Arabidopsis PPR family plus genomic and genetic data on the expression (microarray data), localization (green fluorescent protein and red fluorescent protein fusions), and general function (insertion mutants and RNA binding assays) of many family members. The basic picture that arises from these studies is that PPR proteins play constitutive, often essential roles in mitochondria and chloroplasts, probably via binding to organellar transcripts. These results confirm, but massively extend, the very sparse observations previously obtained from detailed characterization of individual mutants in other organisms.