Thermal Adaptability of the Light-Harvesting Complex 2 from Thermochromatium tepidum: Temperature-Dependent Excitation Transfer Dynamics

Ying Shi, Ning Jiu Zhao, Peng Wang, Li Min Fu, Long Jiang Yu, Jian Ping Zhang, Zheng Yu Wang-Otomo

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8 Citations (Scopus)

Abstract

The photosynthetic purple bacterium Thermochromatium (Tch.) tepidum is a thermophile that grows at an optimal temperature of ∼50 °C. We have investigated, by means of steady-state and time-resolved optical spectroscopies, the effects of temperature on the near-infrared light absorption and the excitation energy transfer (EET) dynamics of its light-harvesting complex 2 (LH2), for which the mesophilic counterpart of Rhodobacter (Rba.) sphaeroides 2.4.1 (∼30 °C) was examined in comparison. In a limited range around the physiological temperature (10-55 °C), the B800-to-B850 EET process of the Tch. tepidum LH2, but not the Rba. sphaeroides LH2, was found to be characteristically temperature-dependent, mainly because of a temperature-tunable spectral overlap. At 55 °C, the LH2 complex from Tch. tepidum maintained efficient near-infrared light harvesting and B800-to-B850 EET dynamics, whereas this EET process was disrupted in the case of Rba. sphaeroides 2.4.1 owing to the structural distortion of the LH2 complex. Our results reveal a remarkable thermal adaptability of the light-harvesting function of Tch. tepidum, which could enhance our understanding of the survival strategy of this thermophile in response to environmental challenges.

Original languageEnglish
Pages (from-to)14871-14879
Number of pages9
JournalJournal of Physical Chemistry B
Volume119
Issue number47
DOIs
Publication statusPublished - Oct 29 2015

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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