Acinetobacter baumannii Regulates Its Stress Responses via the BfmRS Two-Component Regulatory System

Acinetobacter baumannii is a common nosocomial pathogen that utilizes numerous mechanisms to aid its survival in both the environment and the host. Coordination of such mechanisms requires an intricate regulatory network. We report here that A. baumannii can directly regulate several stress-related pathways via the two-component regulatory system BfmRS. Similar to previous studies, results from transcriptomic analysis showed that mutation of the BfmR response regulator causes dysregulation of genes required for the oxidative stress response, the osmotic stress response, the misfolded protein/heat shock response, Csu pilus/fimbria production, and capsular polysaccharide biosynthesis. We also found that the BfmRS system is involved in controlling siderophore biosynthesis and transport, and type IV pili production. We provide evidence that BfmR binds to various stress-related promoter regions and show that BfmR alone can directly activate transcription of some stress-related genes. Additionally, we show that the BfmS sensor kinase acts as a BfmR phosphatase to negatively regulate BfmR activity. This work highlights the importance of the BfmRS system in promoting survival of A. baumannii. IMPORTANCE Acinetobacter baumannii is a nosocomial pathogen that has extremely high rates of multidrug resistance. This organism’s ability to endure stressful conditions is a key part of its ability to spread in the hospital environment and cause infections. Unlike other members of the gammaproteobacteria, A. baumannii does not encode a homolog of the RpoS sigma factor to coordinate its stress response. Here, we demonstrate that the BfmRS two-component system directly controls the expression of multiple stress resistance genes. Our findings suggest that BfmRS is central to a unique scheme of general stress response regulation by A. baumannii

Transcriptional regulation of 'pqsR', a gene that encodes a regulator of quinolone signal synthesis and virulence in 'Pseudomonas aeruginosa'

The gram-negative bacterium 'Pseudomonas aeruginosa' is an opportunistic pathogen that frequently causes nosocomial infections and serious chronic lung infections in cystic fibrosis patients. During infection 'P. aeruginosa' communicates through multiple cell-to-cell signaling molecules to coordinate the expression of numerous virulence determinants. The production of these signaling molecules forms a regulatory network, with the signal N-(3-oxododecanoyl) homoserine lactone and its receptor LasR controlling the induction of a second homoserine lactone signal and the 'Pseudomonas' quinolone signal (PQS). LasR-mediated control of PQS occurs partly through the activation of 'pqsR', a gene that encodes the PQS receptor and is necessary for PQS production. We demonstrate that LasR induces 'pqsR' expression by interacting with a single binding site in the 'pqsR' promoter region that is distant from the 'pqsR' translational start site. Through a search for additional factors that control 'pqsR' expression we found that the transcriptional regulator CysB competes with LasR for binding to the 'pqsR' promoter, and that it negatively affects 'pqsR' expression and PQS production. However, unlike other CysB-controlled genes, 'pqsR' was not differentially regulated in response to cysteine levels. We also show that LasR activates 'pqsR' transcription at a distal promoter site, but other sequences in the 'pqsR' promoter region constitute a negative regulatory element that limits 'pqsR' expression. These findings show that the transcription of 'pqsR', and subsequently PQS production, is controlled by the interplay of both positive and negative regulatory mechanisms. Finding ways to manipulate these regulatory pathways could be a potential strategy to combat 'P. aeruginosa' virulence.Ph.D

Transcriptional regulation of 'pqsR', a gene that encodes a regulator of quinolone signal synthesis and virulence in 'Pseudomonas aeruginosa'

The gram-negative bacterium 'Pseudomonas aeruginosa' is an opportunistic pathogen that frequently causes nosocomial infections and serious chronic lung infections in cystic fibrosis patients. During infection 'P. aeruginosa' communicates through multiple cell-to-cell signaling molecules to coordinate the expression of numerous virulence determinants. The production of these signaling molecules forms a regulatory network, with the signal N-(3-oxododecanoyl) homoserine lactone and its receptor LasR controlling the induction of a second homoserine lactone signal and the 'Pseudomonas' quinolone signal (PQS). LasR-mediated control of PQS occurs partly through the activation of 'pqsR', a gene that encodes the PQS receptor and is necessary for PQS production. We demonstrate that LasR induces 'pqsR' expression by interacting with a single binding site in the 'pqsR' promoter region that is distant from the 'pqsR' translational start site. Through a search for additional factors that control 'pqsR' expression we found that the transcriptional regulator CysB competes with LasR for binding to the 'pqsR' promoter, and that it negatively affects 'pqsR' expression and PQS production. However, unlike other CysB-controlled genes, 'pqsR' was not differentially regulated in response to cysteine levels. We also show that LasR activates 'pqsR' transcription at a distal promoter site, but other sequences in the 'pqsR' promoter region constitute a negative regulatory element that limits 'pqsR' expression. These findings show that the transcription of 'pqsR', and subsequently PQS production, is controlled by the interplay of both positive and negative regulatory mechanisms. Finding ways to manipulate these regulatory pathways could be a potential strategy to combat 'P. aeruginosa' virulence

The Influence of Iron on Pseudomonas aeruginosa Physiology: A regulatory link between iron and quorum sensing

In iron-replete environments the Pseudomonas aeruginosa Fur (ferric uptake regulator) protein represses expression of two small regulatory RNAs encoded by prrF1 and prrF2. Here we describe the effects of iron and PrrF regulation on P. aeruginosa physiology. We show that PrrF represses genes encoding enzymes for the degradation of anthranilate (i.e. antABC) a precursor of the Pseudomonas quinolone signal (PQS). Under ironlimiting conditions PQS production was greatly decreased in a ∆ prrF1 2 mutant as compared with wild type. The addition of anthranilate to the growth medium restored PQS production to the ∆ prrF1 2 mutant indicating that its defect in PQS production is a consequence of anthranilate degradation. PA2511 was shown to encode an anthranilate-dependent activator of the ant genes and was subsequently renamed antR. AntR was not required for regulation of antA by PrrF but was required for optimal iron activation of antA. Furthermore iron was capable of activating both antA and antR in a ∆ prrF1 2 mutant indicating the presence of two distinct yet overlapping pathways for iron activation of antA (AntR-dependent and PrrF-dependent). Additionally several quorum-sensing regulators including PqsR influenced antA expression demonstrating that regulation of anthranilate metabolism is intimately woven into the quorum-sensing network of P. aeruginosa. Overall our data illustrate the extensive control that both iron regulation and quorum sensing exercise in basic cellular physiology underlining how intermediary metabolism can affect the regulation of virulence factors in P. aeruginosa. Originally published Journal of Biological Chemistry vol. 283 No. 23 June 200

Rice, Chilton, and Jones, attorneys, letterbook, W.0049

Abstract: Letterbook containing copies of correspondence written by Montgomery, Alabama, lawyers Samuel F. Rice, John M. Chilton, Thomas G. Jones, and Ariosto A. Wiley, between 1871-1873.Scope and Content Note: This collection consists of one letterbook containing copies of correspondence written by Montgomery, Alabama, lawyers Samuel F. Rice, John M. Chilton, Thomas G. Jones, and Ariosto A. Wiley, between 1871-1873. Most of the letters relate to cases represented by the firm Rice, Chilton, and Jones. Correspondence is cataloged by the author's last name and is listed in the alphabetical directory included in the front of each ledger.Biographical/Historical Note: Rice, Chilton, and Jones was a law firm with an office located in Montgomery, Alabama, at the corner of Market and Perry Street. In 1872, the law firm employed four lawyers: Samuel F. Rice, John M. Chilton, Thomas G. Jones, and Ariosto A. Wiley.Partner Samuel Farrow Rice studied law at South Carolina College and was admitted to the bar in 1837. Rice was elected to the state senate in 1840 and 1841 and was named an associate justice of the Alabama Supreme Court in 1855. In 1856, Rice was named Chief Justice. Rice resigned his post in 1859, returning to his law practice and representing Montgomery and Autauga counties as a state senator and representative.Partner John M. Chilton was admitted to the bar in 1869.Partner Thomas Goode Jones was born on November 26, 1844, in Macon, Georgia. In 1850, Jones's family relocated to Montgomery. A farmer and lawyer, Jones was admitted to the bar in 1868. Between 1875 and 1884, Jones served as Montgomery alderman. In 1884 he was elected to the state house of representatives and became speaker of the house in 1886. In 1890, Jones secured the Democratic nomination and was elected governor of Alabama, serving from 1890-1894. Jones died on April 28, 1914.Ariosto Appling Wiley was born on November 6, 1848, in Clayton, Alabama. He attended Emory and Henry College, where he studied law. In October 1872, Wiley relocated to Montgomery, where he became a member of the Rice, Chilton, and Jones law firm. In 1882 he was elected to represent Montgomery County in the state senate, and in June 1891, he was named lieutenant colonel of the Fifth Regiment of the U.S. Volunteer Infantry. He died on June 17, 1908.Sources: Ulman, H. Charles, "Lawyer's Record and Official Register of the United States," 1872.Owen, Thomas McAdory and Marie Bankhead Owen. History of Alabama and Dictionary of Alabama Biography. Pruitt, Paul McWhorter Jr."Thomas Goode Jones," Encyclopedia of Alabama, http://www.encyclopediaofalabama.org/face/Article.jsp?id=h-1463. Accessed June 10, 2013."Samuel F. Rice," Alabama's Supreme Court Justices, Alabama Department of Archives and History, http://www.archives.alabama.gov/judicial/srice.html. Accessed June 10, 2013