BIOL 155 |
| We have recently reported that Lactobacillus reuteri produces cobalamin and has two cobalamin-related genes in its chromosome. Extension of this sequence revealed the presence of a vitamin B12 gene cluster consisting of 29 open reading frames, encoding the complete enzymatic machinery necessary for de novo synthesis of cobalamin. Transcriptional analysis resorting to Northern blots and reverse transcriptase PCR showed it to be transcribed in two multicistronic operons of approximately 22 and 4 kb. Quantitative reverse transcriptase PCR evidenced that both are similarly regulated, and under the conditions assayed, preferentially expressed during late-exponential phase. Comparative genomics analysis of this sequence showed that it is most similar to the anaerobic B12 pathways characterized in Listeria and Salmonella, possessing the unique feature of clustering the hem and cob genes together. It also provided evidence suggesting that the B12 pathway is ancient to L. reuteri and most likely acquired by horizontal gene transfer. |
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Chemistry and Metabolism
4:30 PM-6:30 PM, Tuesday, 12 September 2006 Moscone Center -- Hall D, Poster
Division of Biological Chemistry |