Identification and characterization of a novel multidrug resistance operon, mdtRP (yusOP), of Bacillus subtilis.

Using comparative genome sequencing analysis, we identified a novel mutation in Bacillus subtilis that confers a low level of resistance to fusidic acid. This mutation was located in the mdtR (formerly yusO) gene, which encodes a MarR-type transcriptional regulator, and conferred a low level of resistance to several antibiotics, including novobiocin, streptomycin, and actinomycin D. Transformation experiments showed that this mdtR mutation was responsible for multidrug resistance.

Transcriptional termination control of a novel ABC transporter gene involved in antibiotic resistance in Bacillus subtilis.

In members of one of the subfamilies of the bacterial ATP binding cassette (ABC) transporters, the two nucleotide binding domains are fused as a single peptide and the proteins have no membrane-spanning domain partners. Most of the ABC efflux transporters of this subfamily have been characterized in actinomycetes, producing macrolide, lincosamide, and streptogramin antibiotics. Among 40 ABC efflux transporters of Bacillus subtilis, five proteins belong to this subfamily.

Modulation of mRNA stability participates in stationary-phase-specific expression of ribosome modulation factor.

The expression of ribosome modulation factor (RMF) is induced during stationary phase in Escherichia coli. RMF participates in the dimerization of 70S ribosomes to form the 100S ribosome, which is the translationally inactive form of the ribosome. To elucidate the involvement of the control of mRNA stability in growth-phase-specific rmf expression, we investigated rmf mRNA stability in stationary-phase cells and cells inoculated into fresh medium.

Increased stability of bmr3 mRNA results in a multidrug-resistant phenotype in Bacillus subtilis.

A spontaneous mutant isolated in the presence of a high concentration of puromycin acquired a multidrug-resistant phenotype. Expression of the bmr3 gene was dramatically increased. A base substitution, T to A at the +4 position, detected in the mutant resulted in the stabilization of bmr3 mRNA.

Bacillus subtilis LmrA is a repressor of the lmrAB and yxaGH operons: identification of its binding site and functional analysis of lmrB and yxaGH.

The Bacillus subtilis lmrAB operon is involved in multidrug resistance. LmrA is a repressor of its own operon, while LmrB acts as a multidrug efflux transporter. LmrA was produced in Escherichia coli cells and was shown to bind to the lmr promoter region, in which an LmrA-binding site was identified.

The BceRS two-component regulatory system induces expression of the bacitracin transporter, BceAB, in Bacillus subtilis.

BceA and bceB encode a nucleotide-binding domain (NBD) and membrane-spanning domain (MSD) subunit, respectively, of an ATP-binding cassette (ABC) transporter in Bacillus subtilis. Disruption of these genes resulted in hypersensitivity to bacitracin, a peptide antibiotic that is non-ribosomally synthesized in some strains of Bacillus. Northern hybridization analyses showed that expression of the bceAB operon is induced by bacitracin present in the growth medium.

Multidrug resistant phenotype of Bacillus subtilis spontaneous mutants isolated in the presence of puromycin and lincomycin.

Spontaneous mutants were isolated by growing Bacillus subtilis 168 in the presence of high concentrations of puromycin and lincomycin. These mutants showed increased resistance to several drugs other than these two drugs. The ImrAB genes, which encode a transcriptional repressor and a drug efflux protein of the major facilitator superfamily, were involved in this phenotype.

Instability of sensory histidine kinase mRNAs in Escherichia coli.

Background: Regulating mRNA stability is one of the essential mechanisms in gene expression. In order to identify genes from Escherichia coli whole genome whose expression is effectively modulated during the process of mRNA decay, we previously performed differential display-PCR as the first step. In the screening, it was suggested that two mRNAs from the histidine kinase genes, narX and yojN, in a two-component signal transduction system, were extremely unstable.

Lincomycin resistance mutations in two regions immediately downstream of the -10 region of lmr promoter cause overexpression of a putative multidrug efflux pump in Bacillus subtilis mutants.

We isolated 19 lincomycin-resistant Bacillus subtilis mutants by expressing lmrB encoding a putative multidrug efflux protein. Eighteen of the mutants altered at two regions (-3 to -1 and +15) immediately downstream of the -10 region of the lmr promoter increased lmr transcription in vivo and in vitro.

A bacitracin-resistant Bacillus subtilis gene encodes a homologue of the membrane-spanning subunit of the Bacillus licheniformis ABC transporter.

Bacitracin is a peptide antibiotic nonribosomally produced by Bacillus licheniformis. The bcrABC genes which confer bacitracin resistance to the bacitracin producer encode ATP binding cassette (ABC) transporter proteins, which are hypothesized to pump out bacitracin from the cells. Bacillus subtilis 168, which has no bacitracin synthesizing operon, has several genes homologous to bcrABC.