The DNA sequence of the relatively large gene encoding the streptococcal- specific Prevotella loescheii adhesin has been completed. Sequence data indicates that the mature adhesin is larger than estimated, 88kD rather than 75kD. The gene, itself, is composed of 2.3kb. A 28 nucleotide base run following the twenty eight codon represents the start of a """"""""ribosomal hop"""""""" which results in a frameshift. The 28 nucleotide sequence starts and ends with an ochre terminator (UAA) and contains two """"""""slippery"""""""" runs of 4 adenines each within the run. A stem loop terminator follows the 28 nucleotide run. Thus far, P. loescheii appears to be only the second bacterium in which short chromosomal sequences within genes are not read. P. loescheii synthesizes at least three extracellular proteases which can be differentiated by ionic charge. At least one of these is capable of degrading the streptococcal-specific adhesin. These enzymes can be separated chromatographically and are currently being purified. The protease may provide the bacterium with a release mechanism from coaggregates or plaque. Enzymes responsible for the transport and metabolism of xylitol ribitol have been purified for the purpose of determining the N-terminal amino acid sequence. Once the sequences are known, DNA probes will be synthesized by backtranslation for the purpose of cloning the genes encoding enzyme IIIxtl, xylitol-5-P dehydrogenase and ribitol-5-P dehydrogenase.
