TY - JOUR
T1 - Association of bacteriochlorophyll a with the CsmA protein in chlorosomes of the photosynthetic green filamentous bacterium Chloroflexus aurantiacus
AU - Sakuragi, Y
AU - Frigaard, N-U
AU - Shimada, K
AU - Matsuura, K
N1 - Keywords: Amino Acids; Bacterial Proteins; Bacteriochlorophylls; Chlorates; Chlorobi; Electrophoresis, Polyacrylamide Gel; Hexanols; Octoxynol; Sodium Hydroxide; Subcellular Fractions; Trypsin
PY - 1999
Y1 - 1999
N2 - The protein assumed to be associated with bacteriochlorophyll (BChl) a in chlorosomes from the photosynthetic green filamentous bacterium Chloroflexus aurantiacus was investigated by alkaline treatment, proteolytic digestion and a new treatment using 1-hexanol, sodium cholate and Triton X-100. Upon alkaline treatment, only the 5.7 kDa CsmA protein was removed from the chlorosomes among six proteins detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis, concomitantly with the disappearance of BChl a absorption at 795 nm. Trypsin treatment removed two proteins with molecular masses of 11 and 18 kDa (CsmN and CmsM), whereas the spectral properties of BChl a and BChl c were not changed. By the new hexanol-detergent (HD) treatment, most BChl c and all of the detected proteins except CsmA were removed from the chlorosomes without changing the BChl a spectral properties. Subsequent proteinase K treatment of these HD-treated chlorosomes caused digestion of CsmA and a simultaneous decrease of the BChl a absorption band. Based on these results, we suggest that CsmA is associated with BChl a in the chlorosomes. This suggestion was supported by the measured stoichiometric ratio of BChl a to CsmA in isolated chlorosomes, which was estimated to be between 1.2 and 2.7 by amino acid analysis of the SDS-PAGE-resolved protein bands.
AB - The protein assumed to be associated with bacteriochlorophyll (BChl) a in chlorosomes from the photosynthetic green filamentous bacterium Chloroflexus aurantiacus was investigated by alkaline treatment, proteolytic digestion and a new treatment using 1-hexanol, sodium cholate and Triton X-100. Upon alkaline treatment, only the 5.7 kDa CsmA protein was removed from the chlorosomes among six proteins detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis, concomitantly with the disappearance of BChl a absorption at 795 nm. Trypsin treatment removed two proteins with molecular masses of 11 and 18 kDa (CsmN and CmsM), whereas the spectral properties of BChl a and BChl c were not changed. By the new hexanol-detergent (HD) treatment, most BChl c and all of the detected proteins except CsmA were removed from the chlorosomes without changing the BChl a spectral properties. Subsequent proteinase K treatment of these HD-treated chlorosomes caused digestion of CsmA and a simultaneous decrease of the BChl a absorption band. Based on these results, we suggest that CsmA is associated with BChl a in the chlorosomes. This suggestion was supported by the measured stoichiometric ratio of BChl a to CsmA in isolated chlorosomes, which was estimated to be between 1.2 and 2.7 by amino acid analysis of the SDS-PAGE-resolved protein bands.
U2 - 10.1016/S0005-2728(99)00092-4
DO - 10.1016/S0005-2728(99)00092-4
M3 - Journal article
C2 - 10556629
SN - 0304-4165
VL - 1413
SP - 172
EP - 180
JO - B B A - General Subjects
JF - B B A - General Subjects
IS - 3
ER -