A LysR‐family transcriptional regulator required for virulence in Brucella abortus is highly conserved among the α‐proteobacteria

Abstract

Summary Small RNAs are principal elements of bacterial gene regulation and physiology. Two small RNAs in Brucella abortus, AbcR1 and AbcR2, are required for wild-type virulence. Examination of the abcR loci revealed the presence of a gene encoding a LysR-type transcriptional regulator flanking abcR2 on chromosome 1. Deletion of this lysR gene (bab1_1517) resulted in the complete loss of abcR2 expression while no difference in abcR1 expression was observed. The B. abortus bab1_1517 mutant strain was significantly attenuated in macrophages and mice, and bab1_1517 was subsequently named vtlR for virulence-associated transcriptional LysR-family regulator. Microarray analysis revealed three additional genes encoding small hypothetical proteins also under the control of VtlR. Electrophoretic mobility shift assays demonstrated that VtlR binds directly to the promoter regions of abcR2 and the three hypothetical protein-encoding genes, and DNase I footprint analysis identified the specific nucleotide sequence in these promoters that VtlR binds to and drives gene expression. Strikingly, orthologs of VtlR are encoded in a wide range of host-associated α-proteobacteria, and it is likely that the VtlR genetic system represents a common regulatory circuit critical for host–bacterium interactions.

Small Noncoding RNA AbcR1 Addressing Multiple Target mRNAs From Transcriptional Factor and Two-Component Response Regulator of Brucella melitensis

“…All the selected targets showed significant up/downregulation with the mutant AbcR1 (Figure 3 B), showing the essential role of conserved nucleotides in the seed region of AbcR1 in gene regulation. This supports the finding that B. abortus VtlR transcription regulator target mRNAs (bab1-0310, bab1-0313, bab1-0314, and bab1-1794) are regulated by AbcR sRNAs and show higher regulatory gene expression with ∆AbcR sRNAs (38). In addition, AbcR sRNAs were reported to control the expression of Lrp-encoded gene BAB1-1587 in B. abortus, and expression decreased with ∆AbcR sRNAs; this finding highlights the importance of AbcR sRNA in the regulation of metabolism and amino acid transport (10).…”

Proline utilization system is required for infection by the pathogenic α-proteobacterium Brucella abortus

“…The column was washed extensively with buffer W (100 mM Tris-HCl and 150 mM NaCl), and the recombinant protein was eluted with 2.5 mM desthiobiotin in buffer W. The degree of purity of the recombinant PutR and PutA was high as judged by SDS-PAGE. Electrophoretic mobility shift assays (EMSAs) ESMAs with recombinant Brucella proteins were performed as described previously [23,24]. All rPutR EMSA experiments were carried out in a 20 µl total reaction volume containing binding buffer composed of 10 mM Tris-HCl (pH 7.4), 50 mM KCl, 1 mM dithiothreitol, 6 % glycerol, 50 µg ml…”

Regulation of cysteine residues in LsrB proteins from Sinorhizobium meliloti under free‐living and symbiotic oxidative stress

“…Lastly, the regulatory mechanism of LsrB could be conserved in rhizobia and some pathogens, because lsrB homologues are also present in Rhizobium, Agrobacterium, Brucella and Bartonella species . Remarkably, a lsrB knockout mutant of Brucella reduced virulence in mice (Sheehan et al, 2015). Hence, our findings, while providing new insights into the function of a symbiosis-related LsrB protein, offer the perspective to analyze LsrB homologues in pathogenic bacteria.…”

“…). Remarkably, a lsrB knockout mutant of Brucella reduced virulence in mice (Sheehan et al ., ). Hence, our findings, while providing new insights into the function of a symbiosis‐related LsrB protein, offer the perspective to analyze LsrB homologues in pathogenic bacteria.…”