Pigments and proteins in green bacterial chlorosomes studied by matrix-assisted laser desorption ionization mass spectrometry

TY - JOUR

T1 - Pigments and proteins in green bacterial chlorosomes studied by matrix-assisted laser desorption ionization mass spectrometry

AU - Persson, S

AU - Sönksen, C P

AU - Frigaard, N-U

AU - Cox, R P

AU - Roepstorff, P

AU - Miller, M

N1 - Keywords: Bacterial Proteins; Chlorobi; Electrophoresis, Polyacrylamide Gel; Organelles; Pigments, Biological; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

PY - 2000

Y1 - 2000

N2 - We have used matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for mass determination of pigments and proteins in chlorosomes, the light-harvesting organelles from the photosynthetic green sulfur bacterium Chlorobium tepidum. By applying a small volume (1 microL) of a concentrated suspension of isolated chlorosomes directly to the target of the mass spectrometer we have been able to detect bacteriochlorophyll a and all the major homologs of bacteriochlorophyll c. The peak heights of the different bacteriochlorophyll c homologs in the MALDI spectra were proportional to peak areas obtained from HPLC analysis of the same sample. The same result was also obtained when whole cells of Chl. tepidum were applied to the target, indicating that MALDI-MS can provide a rapid method for obtaining a semiquantitative determination or finger-print of the bacteriochlorophyll homologs in a small amount of green bacterial cells. In addition to information on pigments, the MALDI spectra also contained peaks from chlorosome proteins. Thus we have been able with high precision to confirm the molecular masses of the chlorosome proteins CsmA and CsmE which have been previously determined by conventional biochemical and genetic methods, and demonstrate the presence of truncated versions of CsmA and CsmB.

AB - We have used matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for mass determination of pigments and proteins in chlorosomes, the light-harvesting organelles from the photosynthetic green sulfur bacterium Chlorobium tepidum. By applying a small volume (1 microL) of a concentrated suspension of isolated chlorosomes directly to the target of the mass spectrometer we have been able to detect bacteriochlorophyll a and all the major homologs of bacteriochlorophyll c. The peak heights of the different bacteriochlorophyll c homologs in the MALDI spectra were proportional to peak areas obtained from HPLC analysis of the same sample. The same result was also obtained when whole cells of Chl. tepidum were applied to the target, indicating that MALDI-MS can provide a rapid method for obtaining a semiquantitative determination or finger-print of the bacteriochlorophyll homologs in a small amount of green bacterial cells. In addition to information on pigments, the MALDI spectra also contained peaks from chlorosome proteins. Thus we have been able with high precision to confirm the molecular masses of the chlorosome proteins CsmA and CsmE which have been previously determined by conventional biochemical and genetic methods, and demonstrate the presence of truncated versions of CsmA and CsmB.

U2 - 10.1046/j.1432-1327.2000.01019.x

DO - 10.1046/j.1432-1327.2000.01019.x

M3 - Journal article

C2 - 10632714

SN - 1742-464X

VL - 267

SP - 450

EP - 456

JO - FEBS Journal

JF - FEBS Journal

IS - 2

ER -