Organization and nucleotide sequence of a gene cluster coding for eight ribosomal proteins in the archaebacterium Halobacterium marismortui

A DNA fragment containing the genes for the eight ribosomal proteins HmaL3, HL6, HmaL23, HmaL2, HmaS19, HmaL22, HmaS3, and HmaL29 from Halobacterium marismortui has been cloned and sequenced. The organization of this gene cluster in general corresponds to the S10 operon of Escherichia coli although there exists some differences between them. The sequence analysis of the 5'- and 3'-region of the gene cluster revealed three open reading frames (orf1, orf2, and orf3) which do not code for any ribosomal protein whose structure is known. A putative promoter is located upstream of orf1. Out of the eight ribosomal proteins five have counterparts in eubacteria only, two in both eubacteria and eukaryotes, and one is exclusively related to an eukaryotic ribosomal protein.