MOLECULAR CHARACTERIZATION OF GENES ENCODING A NOVEL ABC TRANSPORTER IN THERMOANAEROBACTERIUM THERMOSULFURIGENES EM1

The nucleotide sequence of two open reading frames (ORFs) from Thermoa naerobacterium thermosulfurigenes EM1 was determined that encode prote ins with similarity to components of ATP-binding cassette (ABC) transp ort systems. Sequence analysis suggests that the deduced proteins AbcA and AbcB consist of an NH2-terminal membrane-spanning domain and a CO OH-terminal ATP-binding domain. The deduced proteins AbcA and AbcB sho wed highest similarity to proteins of the MsbA subfamily of ABC transp orters, AbcA and AbcB probably function as a heterodimer. An ORF predi cted to encode the primary sigma factor SigA was identified downstream of abcB.