Lepa-1 and cplepa-2 mutant plants displayed slightly high chlorophyll fluorescence and

Lepa-1 and cplepa-2 mutant plants displayed slightly high chlorophyll fluorescence and a pale green phenotype (Figure 3D). Chlorophyll fluorescence analysis of dark-adapted leaves of wild-type and mutant plants showed that the Fv/Fm ratio was slightly lower (0.7660.01) in the 11089-65-9 web cplepa-1 plants than in the wild-type plants (0.8160.01). As shown in Figure 3E, the leaf area of the mutant was approximately 70 that of the wild-type plants 28 d after germination. The chlorophyll content in cplepa-1 was reduced to approximately 88 of the wild-type level, and chlorophyll a/b was decreased to approximately 2.6, compared with 3.0 in the wild-type (Table 1).Chloroplast mRNAs are Associated with Abnormally Few Ribosomes in cplepa-The chloroplast protein synthesis deficiency in the cplepa-1 mutant prompted us to examine the association of chloroplast mRNA with ribosomes. Polysome analysis provides an estimate of the efficiency of translation initiation and elongation [10]. Polysome association was conducted using three-week-old plants grown on soil and MS solid medium. Total leaf lysate was fractionated on a sucrose SPI-1005 gradient under conditions that preserve polysome integrity, and mRNAs purified from the gradient fractions were identified by hybridization with specific probes. The PEP-dependent plastid-encoded atpB, psbA, psbB, and psaA/B transcripts showed a small shift toward the top of the gradient in the cplepa-1 mutant grown on soil (Figure 5). However, the distribution of mutant and wild-type plastid 23S rRNA, ndhA, petA and psaJ transcripts were unchanged in the sucrose gradients (Figures 5 and S2). In addition, the distribution of 23S rRNA along the sucrose gradients showed a different sensitivity to EDTA compared to that of rbcL mRNA (Figure S2). When grown on MS, however, no significant differences in sedimentation between wildtype and mutant plants were detected for the atpB, psbA, psbB, petB, or psaA/B mRNAs (Figure S3). These results indicated that, in the soil-grown cplepa-1 mutant, chloroplast protein translation was impaired.PEP-dependent Chloroplast-encoded mRNA Transcripts are Dramatically Reduced in cplepa-The levels of the chloroplast-encoded transcripts were also investigated by RNA gel blot hybridization using the samecpLEPA in Chloroplast TranslationFigure 2. Immunolocalization and Expression of cpLEPA. A: Immunolocalization analysis of cpLEPA. The chloroplast, thylakoid, stroma and envelope fractions were subjected to immunoblot analysis with specific antisera against cpLEPA. Equal amounts of protein (20 mg) were loaded in each lane. The lanes marked cplepa-1, cplepa-2 and cplepa-1/35s::cpLEPA were loaded with equal amounts of total protein (20 mg). B: Salt washing of the membranes. The thylakoid membranes were incubated with 250 mM NaCl, 200 mM Na2CO3, 1 M CaCl2 and 6 M urea for 30 min at 4uC. Then, the thylakoid proteins were separated by SDS-PAGE and immunoblotted with anti-LEPA, anti-RbcL (ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit) and anti-CP47 antibodies. RbcL and CP47 were used as markers. Thylakoid membrane preparations that had not been subjected to treatment were used as controls. C: Expression patterns of 1313429 cpLEPA. Upper panel: cpLEPA expression levels in different organs of Arabidopsis, ascpLEPA in Chloroplast Translationdetermined by RT-PCR analysis. RNA samples isolated from seedlings, rosettes, flowers, roots, petiole, cauline tissue and siliques of wild-type plants were reverse-transcribed and.Lepa-1 and cplepa-2 mutant plants displayed slightly high chlorophyll fluorescence and a pale green phenotype (Figure 3D). Chlorophyll fluorescence analysis of dark-adapted leaves of wild-type and mutant plants showed that the Fv/Fm ratio was slightly lower (0.7660.01) in the cplepa-1 plants than in the wild-type plants (0.8160.01). As shown in Figure 3E, the leaf area of the mutant was approximately 70 that of the wild-type plants 28 d after germination. The chlorophyll content in cplepa-1 was reduced to approximately 88 of the wild-type level, and chlorophyll a/b was decreased to approximately 2.6, compared with 3.0 in the wild-type (Table 1).Chloroplast mRNAs are Associated with Abnormally Few Ribosomes in cplepa-The chloroplast protein synthesis deficiency in the cplepa-1 mutant prompted us to examine the association of chloroplast mRNA with ribosomes. Polysome analysis provides an estimate of the efficiency of translation initiation and elongation [10]. Polysome association was conducted using three-week-old plants grown on soil and MS solid medium. Total leaf lysate was fractionated on a sucrose gradient under conditions that preserve polysome integrity, and mRNAs purified from the gradient fractions were identified by hybridization with specific probes. The PEP-dependent plastid-encoded atpB, psbA, psbB, and psaA/B transcripts showed a small shift toward the top of the gradient in the cplepa-1 mutant grown on soil (Figure 5). However, the distribution of mutant and wild-type plastid 23S rRNA, ndhA, petA and psaJ transcripts were unchanged in the sucrose gradients (Figures 5 and S2). In addition, the distribution of 23S rRNA along the sucrose gradients showed a different sensitivity to EDTA compared to that of rbcL mRNA (Figure S2). When grown on MS, however, no significant differences in sedimentation between wildtype and mutant plants were detected for the atpB, psbA, psbB, petB, or psaA/B mRNAs (Figure S3). These results indicated that, in the soil-grown cplepa-1 mutant, chloroplast protein translation was impaired.PEP-dependent Chloroplast-encoded mRNA Transcripts are Dramatically Reduced in cplepa-The levels of the chloroplast-encoded transcripts were also investigated by RNA gel blot hybridization using the samecpLEPA in Chloroplast TranslationFigure 2. Immunolocalization and Expression of cpLEPA. A: Immunolocalization analysis of cpLEPA. The chloroplast, thylakoid, stroma and envelope fractions were subjected to immunoblot analysis with specific antisera against cpLEPA. Equal amounts of protein (20 mg) were loaded in each lane. The lanes marked cplepa-1, cplepa-2 and cplepa-1/35s::cpLEPA were loaded with equal amounts of total protein (20 mg). B: Salt washing of the membranes. The thylakoid membranes were incubated with 250 mM NaCl, 200 mM Na2CO3, 1 M CaCl2 and 6 M urea for 30 min at 4uC. Then, the thylakoid proteins were separated by SDS-PAGE and immunoblotted with anti-LEPA, anti-RbcL (ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit) and anti-CP47 antibodies. RbcL and CP47 were used as markers. Thylakoid membrane preparations that had not been subjected to treatment were used as controls. C: Expression patterns of 1313429 cpLEPA. Upper panel: cpLEPA expression levels in different organs of Arabidopsis, ascpLEPA in Chloroplast Translationdetermined by RT-PCR analysis. RNA samples isolated from seedlings, rosettes, flowers, roots, petiole, cauline tissue and siliques of wild-type plants were reverse-transcribed and.