Nucleotide sequence of the gene encoding the 35-kDa protein of Mycobacterium tuberculosis

A 35-kilodalton (kDa) protein of Mycobacterium tuberculosis is expressed by recombinant Escherichia coli which possess a plasmid that contains a 2.4-kilobase fragment of M. tuberculosis chromosomal DNA. The nucleotide sequence of this fragment was determined by the dideoxynucleotide chain-termination method. Analysis of the sequence revealed four open reading frames that could encode proteins greater than 250 amino acids in length. The reading frame for the 35-kDa protein was identified by subcloning DNA fragments into expression vectors pTTQ18 and pTTQ19, and assaying for production of the 35-kDa protein by Western blotting. A protein with a primary structure of 270 amino acids and a predicted molecular weight of 29,260 daltons was deduced from the nucleotide sequence. A computer-aided search of nucleic and amino acid sequence databases did not identify any proteins with significant sequence similarity to this protein. The organization of the gene encoding this protein was compared with other mycobacterial genes that have been sequenced. Information obtained from the investigation of this protein may aid in the development of reagents to diagnose and control mycobacterial disease.