Dataset Information


Cyanophora paradoxa muroplast LC-MSMS

ABSTRACT: Cyanophora paradoxa muroplasts were isolated on a Percoll gradient. Muroplasts were fractionated into soluble (stroma), envelope, and thylakoid proteins. Protein samples from envelope membranes, thylakoids, stroma and total muroplasts were separated by 12% SDS-PAGE. Each Protein lanewas cut into 10 slices of variable size to match similar protein amounts. The gel slices were washed and diced to 1mm3 cubes. Gel pieces were destained by two consecutive washes with a 50:50 mixture of 200 mM ammonium bicarbonate and acetonitrile (ACN) for 20 min at 37°C. Proteins were reduced with 10mM DTT for 45 min at 56°C, followed by alkylation with 55mM iodoacetamide for 45 min at room temperature in the dark. After reduction and alkylation, gel pieces were washed twice with 100 mM ammonium bicarbonate, dehydrated with 100% ACN for 10 min, and dried in a SpeedVac. Gel pieces were fully covered in 50 mM ammonium bicarbonate containing 10ng/ml trypsin and rehydrated at 4°C. The samples were incubated overnight at 37°C and peptides in the supernatant were pooled after successive extraction steps using 50 mM ammonium bicarbonate, 100% ACN and 2.5% formic acid (FA), 50% ACN. The samples were dried in a SpeedVac and reconstituted in 5% ACN, 0.1% FA prior to MS analysis. Each of the samples were analysed in duplicates. Tryptic peptides of the thylakoid, envelope and stroma fractions were loaded onto a fritless 100 μm capillary packed in-house with 10cm of ProntoSIL C18 ace-EPS, 3µm. A gradient of 5-80% (v/v) ACN in 0.1% (v/v) FA was passed over the column with a duration of 115 min. The eluted peptides were directly electrosprayed into the LTQ orbitrap XL MS at a flow rate of 250 nl min-1 and a spray voltage of 1.3 kV. The instrument was operated in a 4-step data-dependent positive mode to identify the top three most abundant ions in a high-resolution MS scan (400 to 2000 m/z), which were then selected for fragmentation. MudPIT analyses were performed on the muroplast samples using an in-house packed analytical column consisting of 10 cm ProntoSIL C18 ace-EPS, 3µm (Bischoff) and 2 cm of a strong cationic exchange (SCX) material, 3µm in combination with an 6-step salt pulse gradient (0, 50, 100, 150, 200 and 500 mM ammonium acetate). Each salt-step peptides were eluted from the SCX to the C18-phase of the analytical column and eluated with a 130- min reverse-phase solvent gradient (5–80% ACN containing 0.1% FA). The eluate was directly electrosprayed into the LTQ orbitrap XL MS which was operated as described before. All MS/MS samples were analyzed using Sequest and X! Tandem. Sequest was set up to search the C. paradoxa nuclear and muroplast protein database with a total of 32,286 entries, assuming the digestion enzyme trypsin. X! Tandem was set up to search a subset of the C. paradoxa database also assuming trypsin. Sequest and X! Tandem were searched with a fragment ion mass tolerance of 0,80 Da and a parent ion tolerance of 10,0 ppm. Oxidation of methionine and iodoacetamide derivatives of cysteine were specified in Sequest and X! Tandem as variable modifications. Scaffold (version 3.5.1, Proteome Software Inc., Portland, OR) was used to validate MS/MS based peptide and protein identifications. Peptide identifications were accepted if they could be established at greater than 95,0% probability as specified by the Peptide Prophet algorithm. Protein identifications were accepted if they could be established at greater than 99,0% probability and contained at least 2 identified peptides.


ORGANISM(S): Cyanophora paradoxa  

TISSUE(S): Not Available

DISEASE(S): Not Available

SUBMITTER: Fabio Facchinelli   

PROVIDER: PXD000056 | Pride | 2012-10-30


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Proteomic analysis of the Cyanophora paradoxa muroplast provides clues on early events in plastid endosymbiosis.

Facchinelli Fabio F   Pribil Mathias M   Oster Ulrike U   Ebert Nina J NJ   Bhattacharya Debashish D   Leister Dario D   Weber Andreas P M AP  

Planta 20121202 2

Glaucophytes represent the first lineage of photosynthetic eukaryotes of primary endosymbiotic origin that diverged after plastid establishment. The muroplast of Cyanophora paradoxa represents a primitive plastid that resembles its cyanobacterial ancestor in pigment composition and the presence of a peptidoglycan wall. To attain insights into the evolutionary history of cyanobiont integration and plastid development, it would thus be highly desirable to obtain knowledge on the composition of the  ...[more]

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