HCF152, an Arabidopsis RNA binding pentatricopeptide repeat protein involved in the processing of chloroplast psbB-psbT-psbH-petB-petD RNAs.
The psbB-psbT-psbH-petB-petD operon of higher plant chloroplasts is a heterogeneously composed transcriptional unit that undergoes complex RNA processing events until the mature oligocistronic RNAs are formed. To identify the nucleus-encoded factors required for the processing and expression of psbB-psbT-psbH-petB-petD transcripts, we performed mutational analysis using Arabidopsis. The allelic nuclear mutants hcf152-1 and hcf152-2 were identified that are affected specifically in the accumulation of the plastidial cytochrome b(6)f complex. In both mutants, reduced amounts of spliced petB RNAs (encoding the cytochrome b(6) subunit) were detected, thus explaining the observed protein deficiencies. Additionally, mutant hcf152-1 is affected in the accumulation of transcripts cleaved between the genes psbH and petB. As a result of a close T-DNA insertion, the HCF152 gene was cloned and its identity confirmed by complementation of homozygous mutant plants. HCF152 encodes a pentatricopeptide repeat (PPR) protein with 12 putative PPR motifs that is located inside the chloroplast. The protein shows a significant structural, but not primary, sequence similarity to the maize protein CRP1, which is involved in the processing and translation of the chloroplast petD and petA RNAs. In addition, we found that HCF152 is an RNA binding protein that binds certain areas of the petB transcript. The protein possibly exists in the chloroplast as a homodimer and is not associated with other proteins to form a high molecular mass complex.
Meierhoff
Karin
K
Heinrich-Heine-Universität, Institut für Entwicklungs und Molekularbiologie der Pflanzen, 40225 Düsseldorf, Germany. karin.meierhoff@uni-duesseldorf.de
Felder
Susanne
S
Nakamura
Takahiro
T
Bechtold
Nicole
N
Schuster
Gadi
G
D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D003573:Cytochrome b Group / Q000235:genetics; D045346:Cytochrome b6f Complex; D004579:Electron Transport / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D017343:Genes, Plant / Q000235:genetics*; D008027:Light; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D010750:Phosphoproteins / Q000235:genetics; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism; D045332:Photosystem II Protein Complex; D010940:Plant Proteins / Q000235:genetics; D011485:Protein Binding; D012323:RNA Processing, Post-Transcriptional; D018747:RNA, Chloroplast / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D020449:Repetitive Sequences, Amino Acid / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D003573:Cytochrome b Group; C477515:HCF152 protein, Arabidopsis; D045342:Light-Harvesting Protein Complexes; C104657:PetB protein, plant; D010750:Phosphoproteins; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D018747:RNA, Chloroplast; D016601:RNA-Binding Proteins; C084072:petD protein, cytochrome b(6)f complex; C063224:photosystem II, psbH subunit; D002734:Chlorophyll; D045346:Cytochrome b6f Complex