oxyfera-like bacteria to total bacteria reached peak values of 2.80% in summer and 4.41% in winter. Phylogenetic analysis showed n-damo bacteria in the paddy soil were closely related to M. oxyfera and had high diversity in the soil/groundwater ecotone. All of the results indicated the soil/groundwater ecotone

of the Jiangyin paddy field was a favorable environment for the growth of n-damo bacteria. “
“Random mutagenesis Selleckchem Ku0059436 has been used to identify the target DNA sites for the MalI repressor at the divergent Escherichia coli K-12 malX-malI promoters. The malX promoter is repressed by MalI binding to a DNA site located from position −24 to position −9, upstream of the malX promoter transcript start. The malI promoter is repressed by MalI binding from position +3 to position +18, downstream of the malI transcript start. MalI binding at the malI promoter target is not required for repression of the malX promoter. Similarly, MalI binding at the malX promoter target is not required for repression of the malI. Although the malX and malI promoters are regulated by a single DNA site for cyclic AMP receptor protein, they function independently and each is repressed by MalI binding to a different independent Selleckchem HIF inhibitor operator site. The Escherichia coli malX and malY genes encode proteins for the transport and metabolism of an

as yet unidentified substrate (Zdych et al., 1995; Clausen et al., 2000). They are cotranscribed from a single promoter (the malX promoter) whose activity is completely dependent on binding of the cyclic AMP receptor protein (CRP) to a single target centred at position −41.5, i.e. between base pairs −41 and −42, upstream from the malXY transcript start (Reidl & Boos, 1991; Lloyd et al., 2008). Upstream of malX, the divergent malI gene encodes a transcription repressor that represses malXY expression (Reidl et al., 1989). Expression of the malI gene is dependent on a single promoter that controls divergent transcription initiation from a location that is 85 base pairs

upstream from the malX promoter transcription startpoint (Lloyd et al., 2008). The malI promoter is factor-independent, but can be activated ∼1.6-fold by CRP binding Sulfite dehydrogenase to its target at the malX promoter, which is centred at position −43.5 with respect to the malI promoter transcription startpoint (Fig. 1). Sequence analysis shows that MalI is a typical member of the LacI family of transcription repressors (Reidl et al., 1989; Weickert & Adhya, 1992). Most members of this family function as dimers that bind to inverted repeats, and Reidl et al. (1989) identified the sequence 5′-GATAAAACGTTTTATC-3′ as a likely target for MalI-dependent repression of the malX promoter. In this work, we describe a genetic screen to prove that this sequence, located from position −24 to position −9 at the malX promoter, and overlapping the −10 hexamer element, is indeed the binding target for MalI.