| Structural highlights
Function
[THIO_ECO57] Participates in various redox reactions through the reversible oxidation of its active center dithiol to a disulfide and catalyzes dithiol-disulfide exchange reactions (By similarity). [ALB3_ARATH] Required for the insertion of some light harvesting chlorophyll-binding proteins (LHCP) into the chloroplast thylakoid membrane. Required for the insertion of LHCB1, LHCB4.1 and LHCB5 proteins into thylakoid membrane, while it is not required for insertion of proteins PsbX, PsbW and PsbY.[1] [2] [3] [4] [SR43C_ARATH] Component of the chloroplast signal recognition particle pathway. Required for post-translational targeting of proteins into the tylakoid membrane but seems to be dispensable for co-translational targeting with a translating ribosome present. May be able to function independently of cpFTSY and FFC/cpSRP54 in targeting LHCPs to the thylakoids. Acts as a highly specific chaperone for LHCPs, preventing aggregation and being able to dissolve aggregates.[5] [6] [7] [8] [9]
Publication Abstract from PubMed
Canonical membrane protein biogenesis requires co-translational delivery of ribosome-associated proteins to the Sec translocase and depends on the signal recognition particle (SRP) and its receptor (SR). In contrast, high-throughput delivery of abundant light-harvesting chlorophyll a,b-binding proteins (LHCPs) in chloroplasts to the Alb3 insertase occurs post-translationally via a soluble transit complex including the cpSRP43/cpSRP54 heterodimer (cpSRP). Here we describe the molecular mechanisms of tethering cpSRP to the Alb3 insertase by specific interaction of cpSRP43 chromodomain 3 with a linear motif in the Alb3 C-terminal tail. Combining NMR spectroscopy, X-ray crystallography and biochemical analyses, we dissect the structural basis for selectivity of chromodomains 2 and 3 for their respective ligands cpSRP54 and Alb3, respectively. Negative cooperativity in ligand binding can be explained by dynamics in the chromodomain interface. Our study provides a model for membrane recruitment of the transit complex and may serve as a prototype for a functional gain by the tandem arrangement of chromodomains.
Structural basis for cpSRP43 chromodomain selectivity and dynamics in Alb3 insertase interaction.,Horn A, Hennig J, Ahmed YL, Stier G, Wild K, Sattler M, Sinning I Nat Commun. 2015 Nov 16;6:8875. doi: 10.1038/ncomms9875. PMID:26568381[10]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Moore M, Harrison MS, Peterson EC, Henry R. Chloroplast Oxa1p homolog albino3 is required for post-translational integration of the light harvesting chlorophyll-binding protein into thylakoid membranes. J Biol Chem. 2000 Jan 21;275(3):1529-32. PMID:10636840
- ↑ Woolhead CA, Thompson SJ, Moore M, Tissier C, Mant A, Rodger A, Henry R, Robinson C. Distinct Albino3-dependent and -independent pathways for thylakoid membrane protein insertion. J Biol Chem. 2001 Nov 2;276(44):40841-6. Epub 2001 Aug 27. PMID:11524428 doi:http://dx.doi.org/10.1074/jbc.M106523200
- ↑ Jiang F, Yi L, Moore M, Chen M, Rohl T, Van Wijk KJ, De Gier JW, Henry R, Dalbey RE. Chloroplast YidC homolog Albino3 can functionally complement the bacterial YidC depletion strain and promote membrane insertion of both bacterial and chloroplast thylakoid proteins. J Biol Chem. 2002 May 31;277(22):19281-8. Epub 2002 Mar 12. PMID:11891220 doi:http://dx.doi.org/10.1074/jbc.M110857200
- ↑ Sundberg E, Slagter JG, Fridborg I, Cleary SP, Robinson C, Coupland G. ALBINO3, an Arabidopsis nuclear gene essential for chloroplast differentiation, encodes a chloroplast protein that shows homology to proteins present in bacterial membranes and yeast mitochondria. Plant Cell. 1997 May;9(5):717-30. PMID:9165749
- ↑ Klimyuk VI, Persello-Cartieaux F, Havaux M, Contard-David P, Schuenemann D, Meiherhoff K, Gouet P, Jones JD, Hoffman NE, Nussaume L. A chromodomain protein encoded by the arabidopsis CAO gene is a plant-specific component of the chloroplast signal recognition particle pathway that is involved in LHCP targeting. Plant Cell. 1999 Jan;11(1):87-99. PMID:9878634
- ↑ Tu CJ, Schuenemann D, Hoffman NE. Chloroplast FtsY, chloroplast signal recognition particle, and GTP are required to reconstitute the soluble phase of light-harvesting chlorophyll protein transport into thylakoid membranes. J Biol Chem. 1999 Sep 17;274(38):27219-24. PMID:10480939
- ↑ Goforth RL, Peterson EC, Yuan J, Moore MJ, Kight AD, Lohse MB, Sakon J, Henry RL. Regulation of the GTPase cycle in post-translational signal recognition particle-based protein targeting involves cpSRP43. J Biol Chem. 2004 Oct 8;279(41):43077-84. Epub 2004 Aug 2. PMID:15292240 doi:http://dx.doi.org/10.1074/jbc.M401600200
- ↑ Tzvetkova-Chevolleau T, Hutin C, Noel LD, Goforth R, Carde JP, Caffarri S, Sinning I, Groves M, Teulon JM, Hoffman NE, Henry R, Havaux M, Nussaume L. Canonical signal recognition particle components can be bypassed for posttranslational protein targeting in chloroplasts. Plant Cell. 2007 May;19(5):1635-48. Epub 2007 May 18. PMID:17513500 doi:http://dx.doi.org/10.1105/tpc.106.048959
- ↑ Falk S, Sinning I. cpSRP43 is a novel chaperone specific for light-harvesting chlorophyll a,b-binding proteins. J Biol Chem. 2010 Jul 9;285(28):21655-61. doi: 10.1074/jbc.C110.132746. Epub 2010, May 24. PMID:20498370 doi:http://dx.doi.org/10.1074/jbc.C110.132746
- ↑ Horn A, Hennig J, Ahmed YL, Stier G, Wild K, Sattler M, Sinning I. Structural basis for cpSRP43 chromodomain selectivity and dynamics in Alb3 insertase interaction. Nat Commun. 2015 Nov 16;6:8875. doi: 10.1038/ncomms9875. PMID:26568381 doi:http://dx.doi.org/10.1038/ncomms9875
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