title: REDUCED CHLOROPLAST COVERAGE genes from Arabidopsis thaliana help to establish the size of the chloroplast compartment.
abstract: Eukaryotic cells require mechanisms to establish the proportion of cellular volume devoted to particular organelles. These mechanisms are poorly understood. From a screen for plastid-to-nucleus signaling mutants in Arabidopsis thaliana, we cloned a mutant allele of a gene that encodes a protein of unknown function that is homologous to two other Arabidopsis genes of unknown function and to FRIENDLY, which was previously shown to promote the normal distribution of mitochondria in Arabidopsis. In contrast to FRIENDLY, these three homologs of FRIENDLY are found only in photosynthetic organisms. Based on these data, we proposed that FRIENDLY expanded into a small gene family to help regulate the energy metabolism of cells that contain both mitochondria and chloroplasts. Indeed, we found that knocking out these genes caused a number of chloroplast phenotypes, including a reduction in the proportion of cellular volume devoted to chloroplasts to 50% of wild type. Thus, we refer to these genes as REDUCED CHLOROPLAST COVERAGE (REC). The size of the chloroplast compartment was reduced most in rec1 mutants. The REC1 protein accumulated in the cytosol and the nucleus. REC1 was excluded from the nucleus when plants were treated with amitrole, which inhibits cell expansion and chloroplast function. We conclude that REC1 is an extraplastidic protein that helps to establish the size of the chloroplast compartment, and that signals derived from cell expansion or chloroplasts may regulate REC1.
authors: Department of Plant Biology, Michigan State University, East Lansing, MI 48824; Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 robertmorganlarkin@gmail.com.
authors: Robert M
authors: RM
authors: Larkin
authors: Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824;
authors: Giovanni
authors: G
authors: Stefano
authors: Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824.
authors: Michael E
authors: ME
authors: Ruckle
authors: Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824;
authors: Andrea K
authors: AK
authors: Stavoe
authors: Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824;
authors: Christopher A
authors: CA
authors: Sinkler
authors: Department of Plant Biology, Michigan State University, East Lansing, MI 48824; Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824;
authors: Federica
authors: F
authors: Brandizzi
authors: Department of Plant Biology, Michigan State University, East Lansing, MI 48824;
authors: Carolyn M
authors: CM
authors: Malmstrom
authors: Department of Plant Biology, Michigan State University, East Lansing, MI 48824;
authors: Katherine W
authors: KW
authors: Osteryoung
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism; D061125:Genes, Chloroplast / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins
keywords: Arabidopsis; chlorophyll; chloroplast; chloroplast coverage; plastid signaling