Light‐induced carotenogenesis in Myxococcus xanthus: DNA sequence analysis of the carR region

Abstract

The carR region encodes a light-inducible promoter, a negative regulator of the promoter and a trans-acting activator that controls the light-inducible Myxococcus xanthus carotenoid biosynthesis regulon. DNA sequence analysis revealed, downstream of the promoter, three translationally coupled genes, carQ, carR and carS. Sequencing of mutations demonstrated that carR encoded the negative regulator and was an integral membrane protein. Mutant construction and sequencing revealed that carS was the trans-acting activator and that carQ was a positive regulator of the promoter. Neither gene encodes proteins with known sequence-specific DNA-binding motifs. The sequence of the light-inducible promoter region, identified by primer extension analysis, showed similarity to the consensus sequence of the Escherichia coli stress response ('heat-shock') promoters.

A manganese transporter, BB0219 (BmtA), is required for virulence by the Lyme disease spirochete, Borrelia burgdorferi

“…Blast searches revealed that, in addition to Bb, functionally uncharacterized homologs of BB0219 exist in other bacteria, such as Borrelia garinii, Borrelia afzelii, Clostridium botulinum, Methanococcus maripaludis, Desulfotalea psychrophila, Staphylococcus epidermidis, and Listeria monocytogenes. Originally, bb0219 was annotated as GufA, a protein with unknown function (22,27). GufA proteins have been placed as a subgroup of the larger ZIP family (25).…”

A Cluster of Structural and Regulatory Genes for Light‐Induced Carotenogenesis in Myxococcus xanthus

“…2. It was 5'-end-labelled with [y-"PJATP, using polynucleotide kinase (Pharmacia), mixed with 50 mg total RNA, heated at 80°C for 10 min, and subsequently annealed at 55°C for 3 h. The extension reaction was performed at 42°C for 60 min, using 10 U avian myeloblastosis reverse transcriptase (Pharmacia) (McGowan et al, 1993). The reaction mixture was fractionated in a 6% polyacrylamide sequencing gel in parallel with dideoxynucleotide sequencing reactions.…”

“…Comparison with the promoter sequences of other light-inducible genes from M. xanrhus, carC and ccirQRS (McGowan et al, 1993) failed to show any significant Botella et al (Eut: J . Biochem.…”

A Repressor-Antirepressor Pair Links Two Loci Controlling Light-induced Carotenogenesis in Myxococcus xanthus

“…The released CarQ is then free to activate transcription from the crtI promoter (P I ). CarQ, in conjunction with CarD and the histone-like protein IhfA, also promotes transcription from its own promoter (P QRS ), leading to increased production in the light of the three proteins encoded in the operon (10,13,14). Photoinduction of the structural genes in the carB operon depends on a different set of regulatory proteins: CarS, encoded by the third gene of the carQRS operon (13), and CarA, produced independently of light from an unlinked operon (Fig.…”