Chloroplast Oxa1p Homolog Albino3 Is Required for Post-translational Integration of the Light Harvesting Chlorophyll-binding Protein into Thylakoid Membranes

Moore, Misty; Harrison, M. Spencer; Peterson, Eric C.; Henry, Ralph

doi:10.1074/jbc.275.3.1529

Cited by 225 publications

(187 citation statements)

References 32 publications

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“…However, despite the correct D1 integration into the thylakoid membrane, assembly of D1 into the PSII RC of ac29 was less efficient as a result of the loss of Alb3.1p. This protein is the homolog of mitochondrial Oxa1p and of bacterial YidC, which have been described as integrases involved in the translocation and/or integration of membrane proteins (Moore et al, 2000(Moore et al, , 2003Kuhn et al, 2003). Nevertheless, it was reported that the integral membrane Cox3p and Pf3 coat protein integrate into membranes independently from Oxa1p and YidC, respectively, although with a lower integration efficiency (Hell et al, 2001;Serek et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

“…This pathway uses the stromal proteins cpSRP54 and cpSRP43, which bind as heterodimers or heterotrimers to the imported LHCPs forming the so-called transit complex. The membrane insertion of the LHCPs strictly requires cpFtsY, GTP, and the integral membrane protein Alb3 in vitro (Tu et al, 1999;Moore et al, 2000Moore et al, , 2003. However, disruption of the genes encoding cpSRP54 and cpSRP43 in Arabidopsis thaliana has only mild effects on the accumulation of LHCPs in comparison with the wild type, whereas the disruption of Alb3p leads to a loss of LHCPs (Sundberg et al, 1997;Tu et al, 1999;Hutin et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

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Efficient Assembly of Photosystem II in Chlamydomonas reinhardtii Requires Alb3.1p, a Homolog of Arabidopsis ALBINO3

et al. 2004

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Alb3 homologs Oxa1 and YidC have been shown to be required for the integration of newly synthesized proteins into membranes. Here, we show that although Alb3.1p is not required for integration of the plastid-encoded photosystem II core subunit D1 into the thylakoid membrane of Chlamydomonas reinhardtii, the insertion of D1 into functional photosystem II complexes is retarded in the Alb3.1 deletion mutant ac29. Alb3.1p is associated with D1 upon its insertion into the membrane, indicating that Alb3.1p is essential for the efficient assembly of photosystem II. Furthermore, levels of nucleus-encoded light-harvesting proteins are vastly reduced in ac29; however, the remaining antenna systems are still connected to photosystem II reaction centers. Thus, Alb3.1p has a dual function and is required for the accumulation of both nucleus- and plastid-encoded protein subunits in photosynthetic complexes of C. reinhardtii

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efficient Assembly of Photosystem II in Chlamydomonas reinhardtii Requires Alb3.1p, a Homolog of Arabidopsis ALBINO3

et al. 2004

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“…They also provided valuable information on the physiology and regulation of chloroplast protein import. Furthermore, maize and Arabidopsis mutants defective in protein transport to the thylakoid also have been isolated (Voelker and Barkan, 1995; Voelker et al, 1997;Roy and Barkan, 1998;Amin et al, 1999;Moore et al, 2000). These mutants helped to further define the various pathways of transport to the thylakoid and even helped to uncover a new export pathway in Escherichia coli .…”

Section: Introductionmentioning

confidence: 99%

Leaf-Specific Upregulation of Chloroplast Translocon Genes by a CCT Motif-Containing Protein, CIA2

Sun¹,

Chen²,

Lin³

et al. 2001

The Plant Cell

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Chloroplasts are a major destination of protein traffic within leaf cells. Protein import into chloroplasts is mediated by a set of translocon complexes at the chloroplast envelope. Current data indicate that the expression of translocon genes is regulated in a tissue-specific manner, possibly to accommodate the higher import demand of chloroplasts in leaves and the lower demand of plastids in other tissues. We have designed a transgene-based positive screen to isolate mutants disrupted in protein import into plastids. The first locus we isolated, CIA2 , encodes a protein containing a motif conserved within the CCT family of transcription factors. Biochemical analysis indicates that CIA2 is responsible for specific upregulation of the translocon genes atToc33 and atToc75 in leaves. Identification of CIA2 provides new insights into the tissue-specific regulation of translocon gene expression. INTRODUCTIONMost proteins in chloroplasts are encoded by the nucleus and imported post-translationally into chloroplasts. Except for some outer envelope membrane proteins, nucleusencoded chloroplast proteins are synthesized as higher molecular weight precursors with N-terminal extensions called transit peptides. Transit peptides are necessary and sufficient for the import of precursor proteins into chloroplasts. Transport across the double membrane envelope is mediated by a set of translocon components located in the envelope. Several translocon components have been identified from pea chloroplasts by cross-linking or coimmunoprecipitating with importing precursor proteins (reviewed by Schleiff and Soll, 2000). They are collectively named Toc (for translocon at the outer envelope membrane of chloroplasts) and Tic (for translocon at the inner envelope membrane of chloroplasts) proteins (Schnell et al., 1997).Among the Toc components identified, Toc159 is proposed to function as the transit peptide receptor (Perry and Keegstra, 1994;Ma et al., 1996). A considerable amount of evidence indicates that Toc75 is the major component of the protein-translocating channel in the outer membrane (Hinnah et al., 1997;Reumann et al., 1999). The function of Toc34 is not clear. It has been shown to be tightly associated with Toc75 (Seedorf et al., 1995). Arabidopsis has two Toc34 orthologs, atToc34 and atToc33. These two proteins seem to have distinct but overlapping functions (Gutensohn et al., 2000).Techniques such as coimmunoprecipitation and crosslinking, when used to identify translocon components, usually identify abundant and stably associated components. Regulatory components that are present in minute amounts or only transiently, and upstream regulators present in different locations, usually are missed by these techniques.More recently, genetics has been used to study protein import into chloroplasts. Arabidopsis mutants have been found for two translocon components, atToc159 (Bauer et al., 2000) and atToc33 (Jarvis et al., 1998). These mutants confirmed that the translocon components identified by cell biology techniques functi...

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“…In Arabidopsis, ALB3 was shown to be essential for the assembly of the light-harvesting complex (LHC) in the thylakoid membrane (Moore et al, 2000). Mutants lacking ALB3 have an albino phenotype (Sundberg et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

One of Two Alb3 Proteins Is Essential for the Assembly of the Photosystems and for Cell Survival in Chlamydomonas

et al. 2006

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Proteins of the YidC/Oxa1p/ALB3 family play an important role in inserting proteins into membranes of mitochondria, bacteria, and chloroplasts. In Chlamydomonas reinhardtii, one member of this family, Albino3.1 (Alb3.1), was previously shown to be mainly involved in the assembly of the light-harvesting complex. Here, we show that a second member, Alb3.2, is located in the thylakoid membrane, where it is associated with large molecular weight complexes. Coimmunoprecipitation experiments indicate that Alb3.2 interacts with Alb3.1 and the reaction center polypeptides of photosystem I and II as well as with VIPP1, which is involved in thylakoid formation. Moreover, depletion of Alb3.2 by RNA interference to 25 to 40% of wild-type levels leads to a reduction in photosystems I and II, indicating that the level of Alb3.2 is limiting for the assembly and/or maintenance of these complexes in the thylakoid membrane. Although the levels of several photosynthetic proteins are reduced under these conditions, other proteins are overproduced, such as VIPP1 and the chloroplast chaperone pair Hsp70/ Cdj2. These changes are accompanied by a large increase in vacuolar size and, after a prolonged period, by cell death. We conclude that Alb3.2 is required directly or indirectly, through its impact on thylakoid protein biogenesis, for cell survival.

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Chloroplast Oxa1p Homolog Albino3 Is Required for Post-translational Integration of the Light Harvesting Chlorophyll-binding Protein into Thylakoid Membranes

Cited by 225 publications

References 32 publications

Efficient Assembly of Photosystem II in Chlamydomonas reinhardtii Requires Alb3.1p, a Homolog of Arabidopsis ALBINO3

Efficient Assembly of Photosystem II in Chlamydomonas reinhardtii Requires Alb3.1p, a Homolog of Arabidopsis ALBINO3

Leaf-Specific Upregulation of Chloroplast Translocon Genes by a CCT Motif-Containing Protein, CIA2

One of Two Alb3 Proteins Is Essential for the Assembly of the Photosystems and for Cell Survival in Chlamydomonas

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