99A-32 |
|
L. TU, Food Science, University of Missouri - Columbia, 256 William Stringer Wing, Eckles Hall, University of Missouri, Columbia, MO 65211, F. Du, Genome Sequencing Center, Washington University School of Medicine, 4444 Forest Park Boulevard, St Louis, MO 63108, and A. Mustapha, Department of Food Science, University of Missouri, 256 Eckles Hall - Stringer Wing, Columbia, MO 65211. Aminoglycoside as a group of antibiotics, includes gentamicin, tobramycin, amikacin and netilmicin. The amino groups of aminoglycosides can be acetylated by aminoglycoside N-acetyltransferases, which is involved in bacterial resistance to the aminoglycosides. Determination of the nucleotide sequence of acetyltransferases will provide insight into the mechanisms of bacterial self protection. However, no data is currently available about aminoglycoside acetyltransferase in bifidobacteria, which is an important probiotic organism in the dairy and functional foods industry. Our objectives were to clone and sequence the aminoglycoside acetyltransferase gene from Bifidobacterium infantis . A genomic DNA library of B. infantis 15702 was constructed in l phage and 5 positive clones were further analyzed. Sequencing was performed by primer walking from both directions of the cloned DNA. Sequence results revealed the presence of one open reading frame spanning 323 bp on a 3277-bp cloned DNA fragment, starting with the ATG codon at position 2589 and terminating with the TGA stop codon at position 2912. The deduced amino acid sequence consists of 108 residues. Comparative analysis of the predicted amino acid sequence with the protein sequence databases revealed that the highest identity was found with Nostoc sp. (strain PCC 7120) and Deinococcus radiodurans (strain R1) (39.1% and 32.6%, respectively). Downstream of the stop codon at position 2942 are sequences which potentially form a stem-loop structure similar to a prokaryotic factor-independent RNA polymerase terminator. There are also 8-bp direct repeats at nucleotides 2677 and 2713, indicating that transposition events might have occurred with the aminoglycoside N3-acetyltransferase gene. Knowledge on the structure of the bifidobacterial aminoglycoside N3-acetyltransferase gene will provide the basis for further genetic manipulation, which could lead to a better understanding of this important organism.
Session 99A, Biotechnology: General
|