Trends in microbiology

Did cathelicidins, a family of multifunctional host-defense peptides, arise from a cysteine protease inhibitor?

Publication Date: 2008 Aug PMID: 18632274
Authors: Zhu, S.
Journal: Trends Microbiol

Cystatins, the cysteine protease inhibitors, and the cathelin-like domain (CLD) of the antimicrobial cathelicidins are classified into the same superfamily because of their overall structural similarity. However, their evolutionary relationship has remained obscure owing to low sequence similarity. Structural similarity of two proteins often provides evidence for divergent evolution; however, structural convergence can not be completely ruled out in this case. Conserved gene structure and related function provide new evidence in favor of a common ancestral origin for cystatins and CLDs. On the basis of two observations, the C-terminal location of the cathelicidin antimicrobial domain and evolutionary gain of one 3' intron, I propose a gradual evolution model to explain how the AMD evolved from the ancestral cystatin scaffold.

post to: CiteULike

Molecular mechanisms of epithelial-barrier disruption by Helicobacter pylori.

Publication Date: 2008 Aug PMID: 18619844
Authors: Wessler, S. - Backert, S.
Journal: Trends Microbiol

Intact intercellular junctions and cell-matrix contacts are important structures in the formation and maintenance of epithelial-barrier functions against microbes. The human gastric pathogen Helicobacter pylori developed a remarkable network of strategies to alter these epithelial cell-cell and cell-matrix adhesions, which are implicated in inflammation, proliferation, cell migration and invasive growth. This review focuses on recent findings on H. pylori-induced host-cell signaling. We propose a stepwise model for how H. pylori interacts with components of focal adhesions and intercellular tight and adherens junctions to disrupt the epithelial layer, providing novel insights into the pathogenesis of H. pylori.

post to: CiteULike

Modulation of stress and virulence in Listeria monocytogenes.

Publication Date: 2008 Aug PMID: 18619843
Authors: Chaturongakul, S. - Raengpradub, S. - Wiedmann, M. - Boor, K. J.
Journal: Trends Microbiol

Listeria monocytogenes can respond rapidly to changing environmental conditions, as illustrated by its ability to transition from a saprophyte to an orally transmitted facultative intracellular pathogen. Differential associations between various alternative sigma factors and a core RNA polymerase provide a transcriptional mechanism for regulating bacterial gene expression that is crucial for survival in rapidly changing conditions. Alternative sigma factors are key components of complex L. monocytogenes regulatory networks that include multiple transcriptional regulators of stress-response and virulence genes, regulation of genes encoding other regulators, and regulation of small RNAs. In this article, the contributions of various sigma factors to L. monocytogenes stress response and virulence are described.

post to: CiteULike

Common themes and variations in serine protease autotransporters.

Publication Date: 2008 Aug PMID: 18595714
Authors: Yen, Y. T. - Kostakioti, M. - Henderson, I. R. - Stathopoulos, C.
Journal: Trends Microbiol

The serine protease autotransporters of the Enterobacteriaceae (SPATEs) represent a group of large-sized, multi-domain exoproteins found only in pathogenic enteric bacteria. These proteins contain a highly conserved channel-forming C-terminal domain, which functions together with YaeT/Omp85 to facilitate secretion of the passenger domain to the cell surface. The C-terminal domain also mediates autoproteolytic cleavage, which releases the passenger from the bacterial cell. The passenger folds into a characteristic parallel beta-helical stalk-like structure with an N-terminal globular domain that performs serine proteolytic activity. Here, we review and discuss recent findings that have led to a better understanding of these unique features in this virulence protein family, including their biogenesis, structural architecture, sequence variation, sub-grouping, evolution and biochemical function.

post to: CiteULike

PCR to predict risk of airborne disease.

Publication Date: 2008 Aug PMID: 18595713
Authors: West, J. S. - Atkins, S. D. - Emberlin, J. - Fitt, B. D.
Journal: Trends Microbiol

Plant, animal and human diseases spread by microscopic airborne particles have had major economic and social impacts during history. Special air-sampling devices have been used to collect such particles since the 19th century but it has often been impossible to identify them accurately. Exciting new opportunities to combine air sampling with quantitative PCR to identify and count these particles are reviewed, using crop pathogen examples. These methods can be used to predict the risk of unexpected outbreaks of airborne diseases by identifying increases in pathogen inoculum or genetic changes in pathogen populations that render control ineffective. The predictions can provide guidance to policymakers, health professionals or the agricultural industry for the development of strategies to minimise the risk of severe pandemics.

post to: CiteULike

The role of virulence determinants in community-associated MRSA pathogenesis.

Publication Date: 2008 Aug PMID: 18585915
Authors: Diep, B. A. - Otto, M.
Journal: Trends Microbiol

The recent emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) marked a quantum change in the biology and epidemiology of a major human pathogen. Various virulence determinants unique to CA-MRSA have been uncovered recently, which shed light on how these strains spread easily and sustainably among humans and frequently cause severe disease. The role of the Panton Valentine leukocidin (PVL) in CA-MRSA pathogenesis is a matter of much debate. Although epidemiological data have indicated a role for PVL in the CA-MRSA disease process, recent data from relevant animal models indicate that PVL does not impact virulence of prevalent CA-MRSA strains. Identifying specialized pathogenic traits of CA-MRSA remains a challenge that will yield new diagnostic tools and therapeutic targets for drug and vaccine development. Here, we discuss the roles of PVL, the arginine catabolic mobile element and phenol-soluble modulins in the pathogenesis of prevalent CA-MRSA strains.

post to: CiteULike