The petD gene is transcribed by functionally redundant promoters in Chlamydomonas reinhardtii chloroplasts.

Sturm, Nancy R.; Kuras, Richard; Büschlen, Sylvie; Sakamoto, Wataru; Kindle, Karen L.; Stern, David B.; Wollman, Françis Andrè

doi:10.1128/mcb.14.9.6171

Cited by 49 publications

(67 citation statements)

References 45 publications

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“…However, we note that in strain mH {DpetD}, the 2-fold reduction in petA transcript level cannot alone account for the 10-fold decreased rate of cytochrome f synthesis, as expected for a regulation operating mainly at the translational level. By contrast, in strain mH {f 307 St}, the 2.5-fold increase in petA mRNA was comparable to the increase in cytochrome f synthesis rate, but we had previously shown that there is little correlation, in an otherwise wild-type genetic context, between the accumulation and the translation of the petA mRNA (Sturm et al, 1994).…”

Section: Mca1-induced Variations In Peta Mrna Abundancementioning

confidence: 75%

The Nucleus-Encodedtrans-Acting Factor MCA1 Plays a Critical Role in the Regulation of CytochromefSynthesis inChlamydomonasChloroplasts

et al. 2011

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Organelle gene expression is characterized by nucleus-encoded trans-acting factors that control posttranscriptional steps in a gene-specific manner. As a typical example, in Chlamydomonas reinhardtii, expression of the chloroplast petA gene encoding cytochrome f, a major subunit of the cytochrome b 6 f complex, depends on MCA1 and TCA1, required for the accumulation and translation of the petA mRNA. Here, we show that these two proteins associate in high molecular mass complexes that also contain the petA mRNA. We demonstrate that MCA1 is degraded upon interaction with unassembled cytochrome f that transiently accumulates during the biogenesis of the cytochrome b 6 f complex. Strikingly, this interaction relies on the very same residues that form the repressor motif involved in the Control by Epistasy of cytochrome f Synthesis (CES), a negative feedback mechanism that downregulates cytochrome f synthesis when its assembly within the cytochrome b 6 f complex is compromised. Based on these new findings, we present a revised picture for the CES regulation of petA mRNA translation that involves proteolysis of the translation enhancer MCA1, triggered by its interaction with unassembled cytochrome f.

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Section: Mca1-induced Variations In Peta Mrna Abundancementioning

confidence: 75%

The Nucleus-Encodedtrans-Acting Factor MCA1 Plays a Critical Role in the Regulation of CytochromefSynthesis inChlamydomonasChloroplasts

et al. 2011

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“…The deletions in these strains, ∆P and FUD6, have been described previously (Sakamoto et al, 1994b;Sturm et al, 1994), and are shown in Figure 4(a). In both ∆P and FUD6, a 4.4 kb petA-petD cotranscript accumulates to a low level because the petD 5Ј processing site has either been compromised (∆P) or deleted (FUD6).…”

Section: ј End Processing Is Required For Transcript Instability In F16mentioning

confidence: 99%

In vivo evidence for 5′→3′ exoribonuclease degradation of an unstable chloroplast mRNA

et al. 1998

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SummaryThe acetate-requiring Chlamydomonas reinhardtii nuclear mutant F16 harbors the mutation mcd1-1 and fails to accumulate the cytochrome b6/f complex. The primary defect of mcd1-1 was determined to be the instability of petD mRNA, which encodes subunit IV of the complex. Chimeric reporter genes introduced by chloroplast transformation demonstrated that the determinant of petD mRNA instability in the mcd1-1 background is located in the 5Ј untranslated region (UTR). However, when this 5Ј UTR was present downstream of other sequences in dicistronic or chimeric transcripts, the RNAs were no longer destabilized in the mcd1-1 background. Together, these results suggest that the 5Ј end of the petD 5Ј UTR interacts with the MCD1 product. The insertion of a polyguanosine sequence into the petD 5Ј UTR fused to a reporter gene allowed accumulation of the reporter gene transcript in the mutant background. Since polyguanosine forms a structure that is known to impede exonucleases, these data provide in vivo evidence that petD mRNA can be degraded by 5Ј→3Ј exoribonuclease activity. Furthermore, the data support a model in which protein binding to the petD 5Ј UTR protects the mRNA from 5Ј→3Ј degradation in wild-type cells.

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“…The ⌬ ycf9 strains did not accumulate the 2.7-kb dicistronic transcript, as determined by hybridization with a psbM probe, but they did accumulate wild-type levels of the 0.7-kb monocistronic psbM transcript ( Figure 2B). Because it has previously been reported that monocistronic transcripts-but not the downstream cistron of dicistronic transcripts-are competent for translation in Chlamydomonas (Sturm et al, 1994;Majeran et al, 2001), it is most likely that we did not compromise the expression of psbM in ⌬ ycf9 strains.In tobacco, ycf9 is located in a small gene cluster flanked by the PSII genes psbD and psbC upstream and trnG downstream. A terminatorless aadA cassette was inserted into the MunI site of ycf9 on the plastid chromosome ( Figure 3A).…”

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confidence: 99%

The Chloroplast Gene ycf9 Encodes a Photosystem II (PSII) Core Subunit, PsbZ, That Participates in PSII Supramolecular Architecture

Świątek¹,

Kuras²,

Sokilenko³

et al. 2001

The Plant Cell

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We have characterized the biochemical nature and the function of PsbZ, the protein product of a ubiquitous open reading frame, which is known as ycf9 in Chlamydomonas and ORF 62 in tobacco, that is present in chloroplast and cyanobacterial genomes. After raising specific antibodies to PsbZ from Chlamydomonas and tobacco, we demonstrated that it is a bona fide photosystem II (PSII) subunit. PsbZ copurifies with PSII cores in Chlamydomonas as well as in tobacco. Accordingly, PSII mutants from Chlamydomonas and tobacco are deficient in PsbZ. Using psbZ -targeted gene inactivation in tobacco and Chlamydomonas, we show that this protein controls the interaction of PSII cores with the light-harvesting antenna; in particular, PSII-LHCII supercomplexes no longer could be isolated from PsbZ-deficient tobacco plants. The content of the minor chlorophyll binding protein CP26, and to a lesser extent that of CP29, also was altered substantially under most growth conditions in the tobacco mutant and in Chlamydomonas mutant cells grown under photoautotrophic conditions. These PsbZ-dependent changes in the supramolecular organization of the PSII cores with their peripheral antennas cause two distinct phenotypes in tobacco and are accompanied by considerable modifications in (1) the pattern of protein phosphorylation within PSII units, (2) the deepoxidation of xanthophylls, and (3) the kinetics and amplitude of nonphotochemical quenching. The role of PsbZ in excitation energy dissipation within PSII is discussed in light of its proximity to CP43, in agreement with the most recent structural data on PSII. INTRODUCTIONWith the completion of an ever-increasing number of chloroplast genome sequences (Quigley and Weil, 1985; Bookjans et al., 1986;Ohyama et al., 1986;Shinozaki et al., 1986; Hiratsuka et al., 1989; Evrard et al., 1990; Hallick et al., 1993; Wakasugi et al., 1994 Wakasugi et al., , 1997Kowallik et al., 1995;Maier et al., 1995;Reith and Munholland, 1995; Douglas and Penny, 1999;Sato et al., 1999; Turmel et al., 1999;Hupfer et al., 2000;Lemieux et al., 2000), the functions of most of the major open reading frames of chloroplast DNA have now been studied. The ability to perform reverse genetics with tobacco and Chlamydomonas chloroplasts has contributed greatly to this process. However, this strategy, which consists mainly of the phenotypic characterization of mutants inactivated for the gene under study, can be unsuccessful in two cases: (1) when the gene product is required for cell viability, in which case homoplasmic transformation cannot be obtained, and (2) when homoplasmic transformants do not display any clear-cut mutant phenotype under laboratory conditions. In both cases, this may preclude a reliable functional characterization of the gene and its product.ycf9 , which is predicted to encode a 6.5-kD protein with two putative membrane-spanning segments, is an interesting case because attempts to inactivate the gene have yielded widely different results ranging from potential lethality to 1 These authors cont...

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The petD gene is transcribed by functionally redundant promoters in Chlamydomonas reinhardtii chloroplasts.

Cited by 49 publications

References 45 publications

The Nucleus-Encodedtrans-Acting Factor MCA1 Plays a Critical Role in the Regulation of CytochromefSynthesis inChlamydomonasChloroplasts

The Nucleus-Encodedtrans-Acting Factor MCA1 Plays a Critical Role in the Regulation of CytochromefSynthesis inChlamydomonasChloroplasts

In vivo evidence for 5′→3′ exoribonuclease degradation of an unstable chloroplast mRNA

The Chloroplast Gene ycf9 Encodes a Photosystem II (PSII) Core Subunit, PsbZ, That Participates in PSII Supramolecular Architecture

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