Chlorosome proteins studied by MALDI-TOF-MS: topology of CsmA in Chlorobium tepidum

Chlorosomes, the light-harvesting apparatus of green bacteria, are a unique antenna system, in which pigments are organized in aggregates rather than associated with proteins. Isolated chlorosomes from the green sulphur bacterium Chlorobium tepidum contain 10 surface-exposed proteins. Treatment of c...

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Bibliographic Details
Published in:Photosynthesis research 2005-11, Vol.86 (1-2), p.113-121
Main Authors: Milks, K.J, Danielsen, M, Persson, S, Jensen, O.N, Cox, R.P, Miller, M
Format: Article
Language:English
Subjects:
Amino Acid Sequence
amino acid sequences
bacterial proteins
Bacterial Proteins - chemistry
Bacterial Proteins - metabolism
bacteriochlorophyll
Chlorobium - chemistry
Chlorobium tepidum
chlorophyll
chlorosome
Desorption
Hydrophobic and Hydrophilic Interactions
light harvesting complex
Mass spectrometry
matrix-assisted laser desorption ionization time-of-flight mass spectrometry
Membrane Proteins - chemistry
Membrane Proteins - metabolism
Molecular Sequence Data
Organelles - chemistry
photosynthesis
photosynthetic reaction centers
pigments
spectral analysis
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Spectrum Analysis
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Summary:Chlorosomes, the light-harvesting apparatus of green bacteria, are a unique antenna system, in which pigments are organized in aggregates rather than associated with proteins. Isolated chlorosomes from the green sulphur bacterium Chlorobium tepidum contain 10 surface-exposed proteins. Treatment of chlorosomes from Chlorobium tepidum with protease caused changes in the spectral properties of bacteriochlorophyll c and digestion of chlorosome proteins. Using SDS-PAGE analysis, immunoblotting and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) we have investigated the topology of the 59-residue CsmA protein. Our results show that at the N-terminus, the only amino acid available for protease degradation is the methionine. At the C-terminus, amino acids can be removed by protease treatment to produce a residual protein containing at least the sequence between residues 2 and 38. These results indicate that the N-terminal portion of the CsmA protein, which is predicted to be mainly hydrophobic, is buried in the chlorosome envelope.
ISSN:0166-8595
1573-5079
DOI:10.1007/s11120-005-3757-4