ISOLATION AND CHARACTERIZATION OF A CARBOXYSOME SHELL GENE FROM THIOBACILLUS-NEAPOLITANUS

The gene coding for the major carboxysome shell peptide (csoS1) from T hiobacillus neapolitanus has been isolated and sequenced. Oligonucleot ide primers for polymerase chain reaction (PCR) amplification of the 5 ' end of the gene were made possible by amino acid sequencing of the N -terminal residues of the shell peptide. A 41 bp PCR product was used as a probe to isolate the gene. The deduced amino acid composition of the 216bp gene shows a high degree of hydrophobicity. The gene is loca ted within a series of three repeated regions of DNA and appears to ha ve arisen via gene duplication. The transcript of csoS1 is approximate ly 400 bases in length. The shell peptide shares significant homology with Synechococcus open reading frames implicated in carboxysome struc ture/assembly. These open reading frames and csoS1 are related and are probably members of a carboxysome gene family.