A chloroplast envelope membrane protein containing a putative LrgB domain related to the control of bacterial death and lysis is required for chloroplast development in Arabidopsis thaliana

Abstract

Summary A protein encoded by At1g32080 was consistently identified in proteomic studies of Arabidopsis chloroplast envelope membranes, but its function remained unclear. The protein, designated AtLrgB, may have evolved from a gene fusion of lrgA and lrgB. In bacteria, two homologous operons, lrgAB and cidAB, participate in an emerging mechanism to control cell death and lysis. We aim to characterize AtLrgB using reverse genetics and cell biological and biochemical analysis. AtLrgB is expressed in leaves, but not in roots. T‐DNA insertion mutation of AtLrgB produced plants with interveinal chlorotic and premature necrotic leaves. Overexpression of full‐length AtLrgB (or its LrgA and LrgB domains, separately), under the control of CaMV 35S promoter, produced plants exhibiting veinal chlorosis and delayed greening. At the end of light period, the T‐DNA mutant had high starch and low sucrose contents in leaves, while the 35S:AtLrgB plants had low starch and high sucrose contents. Metabolite profiling revealed that AtLrgB appeared not to directly transport triose phosphate or hexose phosphates. In yeast cells, AtLrgB could augment nystatin‐induced membrane permeability. Our work indicates that AtLrgB is a new player in chloroplast development, carbon partitioning and leaf senescence, although its molecular mechanism remains to be established.

RIP1, a member of an Arabidopsis protein family, interacts with the protein RARE1 and broadly affects RNA editing

“…Tissue was available from a mutant in the chloroplast polynucleotide phosphorylase, which has a major role in maturing mRNA and rRNA 3′ ends but also participates in RNA degradation through exonucleolytic digestion and polyadenylation (41). We obtained a second mutant that was affected in the gene encoding a chloroplast envelope membrane protein containing a putative LrgB domain, which has been reported recently to play an important role in A. thaliana chloroplast development (42). Examination of the editing extent in two null mutants of the genes encoding these plastid proteins shows no difference from the WT in the editing extent of nad6-161 and cob-325, two mitochondrial sites that show a drastic reduction of editing extent in rip1 (SI Appendix, Fig.…”

Bile Acid Sodium Symporter BASS6 Can Transport Glycolate and Is Involved in Photorespiratory Metabolism in Arabidopsis thaliana

“…Additionally, PLGG1 was identified as a chloroplast protein in proteomic studies. It was originally thought to be involved in programmed cell death, but current evidence now suggests that this phenotype was linked to the accumulation of photorespiratory intermediates (Yang et al, 2012;Pick et al, 2013). However, the Arabidopsis plgg1-1 line showed neither differences in the quantum efficiency of CO 2 assimilation nor changes in the photorespiratory CO 2 compensation point compared with wild type under lowlight conditions (Walker et al, 2016a).…”

Holins in Bacteria, Eukaryotes, and Archaea: Multifunctional Xenologues with Potential Biotechnological and Biomedical Applications

“…They showed that the A. thaliana LrgAB protein can augment nystatin-induced cell permeability when produced in yeast (69). This and other observations led another research group to suggest a role in the induction of programmed cell death of chlorotic cells (72).…”