Parbel, Axel; Scheer, Hugo
Model for the phycobilisome rod with interlocking disks based on domain-weighted linker-polypeptide sequence homologies of Mastigocladus laminosus.
In: International Journal of Photoenergy, Vol. 2: pp. 31-40
The 8 linker-polypeptides from the cyanobacterium Mastigocladus laminosus were examined by comparative amino-acid sequence analysis for the predicted domain structure reported in the literatur (Glauser 1991, Esteban 1993) in detail using split sequences for the rod, rod-core and for the repeats from the core-membrane linker-polypeptide (L-cm (127.6)). This analysis gives two distinct domains, where domain 1 (similar to 22 kDa, identity between 31 and 70%) is present in the N-terminal two thirds of the class II linkers (similar to 30 kDa) and in the repeats of the Lcm 127.6, and domain 2 (similar to 10 kDa, identity between 28 and 41%) in the C-terminal part of the class II rod linkers (L-r(31.5) and L-r(32.5)) and in the two capping linkers (L-c(7.7) and L-r(8.2)). Based on these data, X-ray structure analysis from phycobiliproteins and proteolysis experiments, an interlocking model for the phycobilisome rod organization is proposed, with linkers protruding from one phycobilisome disk into the neighbouring one.