Gene sequencing and characterization of the light-harvesting complex 2 from thermophilic purple sulfur bacterium Thermochromatium tepidum

Fumie Sekine, Kentaro Horiguchi, Yasuhiro Kashino, Yuuki Shimizu, Long-Jiang Yu, Masayuki Kobayashi, Zheng Yu Wang

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

In this study, gene sequences coding for the light-harvesting (LH) 2 polypeptides from a thermophilic purple sulfur bacterium Thermochromatium tepidum are reported and characterization of the LH2 complex is described. Three sets of pucBA genes have been identified, and the gene products have been analyzed by electrophoresis and reversed-phase chromatography. The result shows that all of the genes are expressed but the distribution of the expression is not uniform. The gene products undergo post-translational modification, where two of the β-polypeptides appear to be N-terminally methylated. Absorption spectrum of the purified LH2 complex exhibits Q y transitions at 800 and 854 nm in dodecyl β-maltopyranoside solution, and the circular dichroism spectrum shows a "molischianum"-like characteristic. No spectral change was observed for the LH2 when the bacterium was cultured under different conditions of light intensity. In lauryl dimethylamine N-oxide (LDAO) solution, significant changes in the absorption spectrum were observed. The B850 peak decreased and blue-shifted with increasing the LDAO concentration, whereas the B800 intensity increased without change in the peak position. The spectral changes can be partially or almost completely reversed by addition of metal ions, and the divalent cations seem to be more effective. The results indicate that ionic interactions may exist between LH2, detergent molecules and metal ions. Possible mechanisms involved in the detergent- and cation-induced spectral changes are discussed.

Original languageEnglish
Pages (from-to)9-18
Number of pages10
JournalPhotosynthesis Research
Volume111
Issue number1-2
DOIs
Publication statusPublished - Mar 2012
Externally publishedYes

Fingerprint

Thermochromatium tepidum
Chromatiaceae
light harvesting complex
Sulfur
Bacteria
Genes
dimethylamine
Light
metal ions
detergents
oxides
polypeptides
cations
genes
Detergents
Oxides
Metal ions
Absorption spectra
circular dichroism spectroscopy
Metals

Keywords

  • Energy transfer
  • Membrane protein
  • Photosynthesis
  • Sulfur bacteria

ASJC Scopus subject areas

  • Plant Science
  • Cell Biology
  • Biochemistry

Cite this

Gene sequencing and characterization of the light-harvesting complex 2 from thermophilic purple sulfur bacterium Thermochromatium tepidum. / Sekine, Fumie; Horiguchi, Kentaro; Kashino, Yasuhiro; Shimizu, Yuuki; Yu, Long-Jiang; Kobayashi, Masayuki; Wang, Zheng Yu.

In: Photosynthesis Research, Vol. 111, No. 1-2, 03.2012, p. 9-18.

Research output: Contribution to journalArticle

Sekine, Fumie ; Horiguchi, Kentaro ; Kashino, Yasuhiro ; Shimizu, Yuuki ; Yu, Long-Jiang ; Kobayashi, Masayuki ; Wang, Zheng Yu. / Gene sequencing and characterization of the light-harvesting complex 2 from thermophilic purple sulfur bacterium Thermochromatium tepidum. In: Photosynthesis Research. 2012 ; Vol. 111, No. 1-2. pp. 9-18.
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