AMINO ACID SEQUENCE ANALYSIS OF THE SMALL SUBUNIT OF RIBULOSE BISPHOSPHATE CARBOXYLASE FROM FUCUS (PHAEOPHYCEAE)¹

Abstract

This paper reports for the first time amino acid sequence information for the small subunit of ribulose‐1,5‐bisphosphate carboxylase / oxygenase (Rubisco) from a non‐green alga. N‐terminal sequences are presented for the polypeptide from three species of the genus Fucus (Phaeophyceae). Although homologous to small subunit polypeptides from other organisms, the Fucus sequences exhibit a unique N‐terminal section resembling neither cyanobacterial nor chlorophytic sequences. This difference may be a consequence of the plastid DNA coding arrangement for the small subunit in chromophytes, a situation reported for the related organism Olisthodiscus but not previously investigated at the amino acid sequence level.

Evolution of the Rubisco operon from prokaryotes to algae: Structure and analysis of the rbcS gene of the brown alga Pylaiella littoralis

“…3). The amino terminus of the small subunit of Rubisco from the brown alga Fucus serratus [21] has been included in this comparison. It is clear from this alignment that these 15 sequences segregate into two homogeneous groups based on regions of sequence homology, particularly in the terminal domains.…”

The small subunit of ribulose-1,5-bisphosphate carboxylase is plastid-encoded in the chlorophyll c-containing alga Cryptomonas ?

“…Triplication of the sequence GCT has resulted in the insertion of two cysteine residues at position 94 and 95 relative to all other small subunits investigated thus far. Compared to all other plants, cyanobacteria and algae (except Fucus [7]), the small subunit from Cryptomonas is missing approximately 4-7 amino acids from the amino terminus and the signal peptide characteristic of all nuclear-encoded small-subunit genes. It is also lacking a single amino acid between positions 40 and 41, and 11 amino acids between positions 46 and 47, relative to most other plants and algae.…”

“…This indicates that the Fucus plastid evolved from a cryptomonad-like plastid ancestor rather than a cyanobacterial or red algalike ancestor. The amino-terminal 41 amino acids of the small subunit from Fucus have been shown to contains sections unlike either cyanobacteria, land plants or chlorophytic algae [7] and these are shared with Cryptomonas ¢. It is larger than other small subunits even though it does not contain the characteristic 7 amino acids which are present at There may be extra sequences at the carboxy terminus or internally as in Chlamydomonas reinhardtii [6] and Euglena gracilis [ 18].…”

Rubisco genes indicate a close phylogenetic relation between the plastids of Chromophyta and Rhodophyta

“…= cyanobacteria[6,31,34,35]; Chl.b = chlorophyll a/b plants[3, 8,11,13,25,27,43]; F.ser. = Fucus serratus (Chromophyta, Phaeophyceae,[ 18]). In the case of Fucus (values in brackets) only the first 40 amino acids have been determined[18].…”

“…= Fucus serratus (Chromophyta, Phaeophyceae,[ 18]). In the case of Fucus (values in brackets) only the first 40 amino acids have been determined[18]. Homologies to cyanobacteria and chlorophyll a/b plants are average values.…”