A library was constructed for whole chloroplast DNA of Bryopsis maxima. Sau3A 1 partial digests of chloroplast DNA were cloned at BamHI sites of )~ dash vectors. The library, screened with the DNA probe of the large subunit (LS) of cyanobacterium Rubisco [ 1 ], showed positive hybridization to 50 out of approximately 9000 plaques. DNA from the positively hybridizing 9 plaques were isolated. Restriction and Southern hybridization analyses indicated a phage, designated as 2MHB7, to have the longest insert of about 17 kb among the 9 clones and to contain the whole rbcL of B. maxima. The nucleotide sequence determined by dideoxy chain termination and the deduced amino acid sequence for rbcL and its surroundings are presented in Fig. 1. rbcL contained 1425 bp, coding 475 amino acids, and the sequence showed 67~o homology with that ofA. nidulans used as a probe. The deduced amino acid sequence of B. maxima LS protein showed 92~o homology with that of Chlorella LS protein and 90~o ho-mology with that of Chlamydomonas LS protein. The amino acid sequences of RuDP-binding sites and CO2-binding site of B. maxima LS protein showed as much of 96~o homology to those of Chlamydomonas. An intron of 2467 bp was found between codons 268 and 269 of B. maxima rbcL. The boundary sequences of the intron most resembled the group III intron described for chloroplast DNA [2]. There was an open reading frame of 822 bp in this intron. It showed no significant homology with the sequences in the GenBank database, but its transcribed products were detected by northern blotting using the whole of the reading frame as a probe. Efforts are now being made to assess the physiological significance of this region. A sequence located 118 bp upstream from the B. maxima rbcL initiation site for translation was identical with that of the -10 box of the LS promoter region ofrbcL of tobacco, maize and spinach. The sequence T-T-G-G-T-T (at the position of 19 bp upstream from the -10 box)
The nucleotide sequence data reported will appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession number X55877.