A Conserved Inverted Repeat, the LipR Box, Mediates Transcriptional Activation of the Streptomyces exfoliatus Lipase Gene by LipR, a Member of the STAND Class of P-Loop Nucleoside Triphosphatases

Abstract

Expression of the Streptomyces exfoliatus lipA gene, which encodes an extracellular lipase, depends on LipR, a transcriptional activator that belongs to the STAND class of P-loop nucleoside triphosphatases. LipR is closely related to activators present in some antibiotic biosynthesis clusters of actinomycetes, forming the LipR/TchG family of regulators. In this work we showed that purified LipR protein is essential for activation of lipA transcription in vitro and that this transcription depends on the presence of a conserved inverted repeat, the LipR box, located upstream of the lipA promoter. Mutagenesis of the lipA promoter region indicated that most transcription depends on LipR binding to the proximal half-site of the LipR box in close proximity to the ؊35 region of the promoter. Our experiments also indicated that LipR establishes contact with the RNA polymerase on both sides of the LipR box, since some activation was observed when only the distal half-site was present or when the entire LipR box was moved further upstream. We also showed that the LipR proteins of S. exfoliatus and Streptomyces coelicolor are functionally interchangeable both in vitro and in vivo, revealing the functional conservation of the regulatory elements in these two species.

Characterization of the CrbS/R Two-Component System in Pseudomonas fluorescens Reveals a New Set of Genes under Its Control and a DNA Motif Required for CrbR-Mediated Transcriptional Activation

“…CrbR is a member of the LuxR family, whose members are known to recognize and bind inverted repeats (Evangelista-Martínez et al, 2006 ; Antunes et al, 2008 ). To identify any conserved motifs required for CrbR-mediated promoter induction, we obtained the sequence of the putative promoter region of acs homologs from 31 Gammaproteobacteria (Table 3 ) and ran a motif search using the MEME, a tool for the discovery of novel, ungapped motifs in sequences (Bailey et al, 2009 ).…”

Degradation and assimilation of aromatic compounds by Corynebacterium glutamicum: another potential for applications for this bacterium?

“…PcaR exerts its regulatory role by interacting with 15-bp operator sequences that are located in the pcaI-pcaR intergenic region and upstream of pcaH and pobA. PcaO is the first LAL-type regulator involved in aromatic compounds catabolism (Zhao et al 2010), although the involvement of LAL-type regulators in regulation of different metabolic pathways has been intensively characterized (Panagiotidis et al 1998;van Beilen et al 2001;Evangelista-Martínez et al 2006). In vitro EMSA results showed that ATP weakened the binding between PcaO and its target sequence but ADP strengthened this binding, while the effect of protocatechuate on PcaO binding was dependent on the protocatechuate concentration.…”

PcaO Positively Regulates pcaHG of the β-Ketoadipate Pathway in Corynebacterium glutamicum

“…The highest level of identity found was the level of identity between PcaO and a putative regulator of benzoate degradation (BenR, NCgl2324) of C. glutamicum (28% identity) (14,15,35). The levels of identity between PcaO and other LAL regulators, including LipR of Streptomyces coelicolor (42), LipR of Streptomyces exfoliatus (9), PikD of Streptomycoes venezuelae (47), AcoK of Klebsiella pneumoniae (27), AlkS of Pseudomonas oleovorans (48), and MalT of E. coli (29), were less than 20%. We concluded that this PcaO was a novel and atypical LAL-type regulator.…”

“…According to amino acid sequence analysis, PcaO is phylogenetically related to members of the previously proposed LAL subfamily of bac- PcaO is the first LAL-type regulator involved in catabolism of aromatic compounds, although the involvement of LALtype regulators in regulation of different metabolic activities has been intensively characterized. The MalT protein in E. coli regulates catabolism of maltose (24,29), the AlkS protein in P. oleovorans regulates degradation of medium-chain-length alkanes (43,48), the LipR proteins in S. exfoliatus and S. coelicolor regulate transcription of lipase (9,42), the AcoK protein in K. pneumoniae regulates acetoin degradation (27), and the PikD protein in S. venezuelae regulates pikromycin synthesis (47). It has been proposed that LAL-type regulators are involved in regulation of diverse types of metabolism in both Gram-negative and Gram-positive bacteria, but their regulatory mechanisms might be different.…”