Fusion of proteoliposomes containing the B800-850 light-harvesting complex with membranes of the mutant strain NK3 ofRhodopseudomonas capsulatalacking B800-850

✍ Scribed by Augusto F. Garcia; Nasser Gad'on; Gerhart Drews

• Book ID: 104761388
• Publisher: Springer
• Year: 1985
• Tongue: English
• Weight: 432 KB
• Volume: 141
• Category: Article
• ISSN: 0302-8933
• DOI: 10.1007/bf00408065

✦ Synopsis

Intracytoplasmic membranes of the mutant strain NK3 of Rhodopseudomonas capsulata lacking the lightharvesting complex B800-850 were fused with proteoliposomes containing the B800-850 complex. Fluorescence emission spectroscopy at 77 K showed that after fusion the fluorescence of the B850 bacteriochlorophyll disappeared nearly completely and the B870 fluorescence became prominent. This result and control experiments with proteoliposome-chromatophore mixture and with chromatophore and solubilized B800-850 complexes, respectively, indicate that in fused membranes a reorientation of membrane particles took place and excitons migrated from B850 to B870 bacteriochlorophyll.

In fused proteoliposome-chromatophore vesicles a lightinduced carotenoid band shift was observed, reflecting the building of an electrical membrane potential due to chargeseparation. Carotenoid band shift was not observed in separated proteoliposomes and NK3 chromatophores.

It is concluded that by membrane fusion and lateral diffusion of membrane particles reaction center-lightharvesting B870 complexes came in functional contact with B800-850 antenna complexes.