1: Microbiology. 2007 Jul;153(Pt 7):2304-11.

Genetic and physiological characterization of the Borrelia burgdorferi ORF
BB0374-pfs-metK-luxS operon.

Riley SP, Bykowski T, Babb K, von Lackum K, Stevenson B.

Department of Microbiology, Immunology and Molecular Genetics, University of
Kentucky College of Medicine, MS415 Chandler Medical Center, Lexington, KY
40536-0298, USA.

The Lyme disease spirochaete, Borrelia burgdorferi, produces the LuxS enzyme both
in vivo and in vitro; this enzyme catalyses the synthesis of homocysteine and
4,5-dihydroxy-2,3-pentanedione (DPD) from a by-product of methylation reactions. 
Unlike most bacteria, B. burgdorferi is unable to utilize homocysteine. However, 
DPD levels alter expression levels of a subset of B. burgdorferi proteins. The
present studies demonstrate that a single B. burgdorferi operon encodes both of
the enzymes responsible for synthesis of DPD, as well as the enzyme for
production of the Lyme spirochaete's only activated-methyl donor and a probable
phosphohydrolase. Evidence was found for only a single transcriptional promoter, 
located 5' of the first gene, which uses the housekeeping sigma(70) subunit for
RNA polymerase holoenzyme function. All four genes are co-expressed, and mRNA
levels are growth-rate dependent, being produced during the exponential phase.
Thus, high metabolic activity is accompanied by increased cellular levels of the 
only known borrelial methyl donor, enhanced detoxification of methylation
by-products, and increased production of DPD. Therefore, production of DPD is
directly correlated with cellular metabolism levels, and may thereby function as 
an extracellular and/or intracellular signal of bacterial health.


PMID: 17600074 [PubMed - indexed for MEDLINE]

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