Disease relevance of repA

• Transcription of repA, the gene of the initiation protein of the Pseudomonas plasmid pPS10, is autoregulated by interactions of the RepA protein at a symmetrical operator [1].
• This region (ori) confers functions sufficient for replication in Agrobacterium and Rhizobium species but not in Pseudomonas solanacearum, Pseudomonas glumae, Pseudomonas syringae pv. savastanoi, Xanthomonas campestris pv. campestris, and Escherichia coli. ori contains a repA gene that encodes a 28,000-dalton protein required for replication [2].
• Similarities between the DNA replication initiators of Gram-negative bacteria plasmids (RepA) and eukaryotes (Orc4p)/archaea (Cdc6p) [3].
• An autoreplicative region of 2.79 kb named RepA/C, able to replicate both in the family Enterobacteriaceae and in Pseudomonas spp., was isolated and sequenced [4].
• The highest similarity was observed with homologous proteins (RepA) encoded by the repABC family of replicons found in several plasmids of Agrobacterium, Rhizobium and Paracoccus spp [5].

High impact information on repA

• RepA is the DNA replication initiator protein of the Pseudomonas plasmid pPS10 [6].
• Protein domains and conformational changes in the activation of RepA, a DNA replication initiator [6].
• We have previously shown that a Leucine Zipper-like motif (LZ) at the N-terminus of RepA is responsible for protein dimerization [6].
• It is shown that the LZ motif modulates the equilibrium between monomeric and dimeric forms of the protein and that monomers of RepA interact with sequences at the origin of replication, oriV, while dimers are required for interactions of RepA at the repA promoter [7].
• Leucines at the d positions of the putative alpha-helix are relevant in the formation of RepA dimers required for transcriptional autoregulation [7].

Chemical compound and disease context of repA

• Two genes, designated repA and repB, are involved in the regulation of the synthesis of extracellular pectate lyase, protease, and alginate in Pseudomonas viridiflava [8].

Biological context of repA

• Phylogenetic comparisons between IncFII-like plasmids, together with previous in vitro and in vivo results (Ohman and Wagner, 1989, 1991), suggest that a stable RNA stem-loop structure sequesters the repA ribosome binding site irrespective of CopA-CopT duplex formation [9].
• A reading frame for a 24 amino acid leader peptide (Tap, translational activator peptide) is located in the region between the copA and repA genes [9].
• The core of the repA operator region is formed by two in-phase invertedly repeated sequences of 8 bp, S1 and S2, that flank the -35 box of the promoter, and that share homology with the internal sequences of the iterons present in the origin of replication [1].
• RepA protein, encoded in the Pseudomonas pPS10 replicon, is a stable dimer in solution (dRepA), acting as a self-repressor of repA transcription through binding to an inverted repeat operator [10].
• Transcription of the repA gene of the Pseudomonas plasmid pPS10 is initiated from a sigma 70 type promoter located 81 bp upstream from the repA gene, extends through the repA gene and the adjacent open reading frame, and ends 1114 nucleotides downstream [1].

Analytical, diagnostic and therapeutic context of repA

• High concentrations of bovine serum albumin or ovalbumin (macromolecular crowding) enhance RepA affinity for an iteron in solution and, in gel mobility-shift assays, result in the visualization of novel protein-DNA complexes [10].
• Binding curves of RepA to an iteron, followed by fluorescence anisotropy in solution and by surface plasmon resonance on immobilized DNA, exhibit the profiles characteristic of transitions between three states [10].
• On the basis of CD spectroscopy, hydrodynamics, X-ray crystallography and model building studies, we proposed previously that the activation of RepA initiator implies a large structural change in WH1, coupled to protein monomerization and interdomain compaction [10].

References