Andrew J. Darwin

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Inducible extracytoplasmic stress responses (ESRs) help to maintain the integrity and function of the bacterial cell envelope in unfavorable conditions. ESRs can also have highly specialized functions linked to virulence-associated systems directly. One of the most intriguing and yet enigmatic examples is the widely conserved phage shock protein (Psp)(More)
The expression of several Escherichia coli operons is activated by the Fnr protein during anaerobic growth and is further controlled in response to nitrate and nitrite by the homologous response regulators, NarL and NarP. Among these operons, the napF operon, encoding a periplasmic nitrate reductase, has unique features with respect to its Fnr-, NarL-, and(More)
Secretins are bacterial outer membrane proteins that are important for protein export. However, they can also mislocalize and cause stress to the bacterial cell, which is dealt with by the well-conserved phage shock protein (Psp) system in a highly specific manner. Nevertheless, some bacteria have secretins but no Psp system. A notable example is(More)
Known inducers of the phage shock protein (Psp) system suggest that it is an extracytoplasmic stress response, as are the well-studied RpoE and Cpx systems. However, a random approach to identify conditions and proteins that induce the Psp system has not been attempted. It is also unknown whether the proteins or mutations that induce Psp are specific or if(More)
UNLABELLED Elongation factor P (EF-P) is a ubiquitous bacterial protein that is required for the synthesis of poly-proline motifs during translation. In Escherichia coli and Salmonella enterica, the posttranslational β-lysylation of Lys34 by the PoxA protein is critical for EF-P activity. PoxA is absent from many bacterial species such as Pseudomonas(More)
An obvious goal in the study of bacteria that cause human disease is to identify the bacterial genes required for growth within the host. Historically, this has presented a significant technological challenge. However, with this goal in mind, the in vivo expression technology (IVET) and signature-tagged mutagenesis (STM) techniques were developed during the(More)
Yersinia enterocolitica causes human gastroenteritis, and many isolates have been classified as either "American" or "non-American" strains based on their geographic prevalence and virulence properties. In this study we describe identification of a transcriptional regulator that controls expression of the Y. enterocolitica ytxAB genes. The ytxAB genes have(More)
The phage shock protein (Psp) system is a conserved extracytoplasmic stress response in bacteria that is essential for virulence of the human pathogen Yersinia enterocolitica. This article summarizes some recent findings about Y. enterocolitica Psp system function. Increased psp gene expression requires the transcription factor PspF, but under non-inducing(More)
We report a significantly improved system for studying single-copy lacZ operon fusions in Yersinia enterocolitica: a simple procedure for the stable integration of lacZ operon fusions into the ara locus and a strain with a deletion mutation that abolishes the low level of endogenous beta-galactosidase activity.
The cell envelope of pathogenic bacteria is a barrier against host environmental conditions and immunity molecules, as well as the site where many virulence factors are assembled. Extracytoplasmic stress responses (ESRs) have evolved to help maintain its integrity in conditions where it might be compromised. These ESRs also have important links to the(More)