Plant Biology*
Complexome Profiling Reveals Association of PPR Proteins with Ribosomes in the Mitochondria of PlantsPlant mitochondrial protein expression is complex and routinely involves pentatricopeptide repeat proteins for processing of transcripts. Although the composition and structure of the mitoribosomes in other eukaryotic kingdoms of life is well established, plant mitochondria have so far eluded a detailed analysis. Using a complexome profiling approach, this study provides an early glimpse on the composition of plant mitochondrial ribosomes and sheds new light on the process of mitochondrial gene expression in plants. Mitochondrial subunits were found to possess several additional proteins carrying pentatricopeptide repeats potentially involved in RNA editing. Other proteins are potentially involved in the processing of nascent proteins.
Unraveling Hidden Components of the Chloroplast Envelope Proteome: Opportunities and Limits of Better MS SensitivityBy quantitatively comparing the proteomes of total leaf (crude cell extract) from Arabidopsis and purified chloroplast envelope fractions, this study makes available a novel parameter (calculated Enrichment Factor) for each putative envelope protein. This parameter provides important information to enable the more confident identification of genuine envelope components, distinguishing them from contaminants from other cellular/chloroplast compartments.
Quantitative Early Auxin Root Proteomics Identifies GAUT10, a Galacturonosyltransferase, as a Novel Regulator of Root Meristem MaintenanceAuxin induces rapid abundance changes in various signaling proteins, transcriptional regulators, and enzymes such as cell wall modification proteins in roots. Loss of function of 15 top responsive proteins results in altered root phenotypes, demonstrating the power of this approach for reverse genetics screens. Characterization of the auxin responsive protein galacturonosyltransferase 10 demonstrates that this enzyme positively regulates sugar-mediated root meristem maintenance. Novel targeted proteomics assays demonstrate that all six auxin receptors remain stable in response to hormone.