OmpA family proteins and Pmp-like autotransporter: new adhesins of Waddlia chondrophila.

Waddlia chondrophila is a obligate intracellular bacterium belonging to the Chlamydiales order, a clade that also includes the well-known classical Chlamydia responsible for a number of severe human and animal diseases. Waddlia is an emerging pathogen associated with adverse pregnancy outcomes in humans and abortion in ruminants. Adhesion to the host cell is an essential prerequisite for survival of every strict intracellular bacteria and, in classical Chlamydia, this step is partially mediated by polymorphic outer membrane proteins (Pmps), a family of highly diverse autotransporters that represent about 15% of the bacterial coding capacity. Waddlia chondrophila genome however only encodes one putative Pmp-like protein. Using a proteomic approach, we identified several bacterial proteins potentially implicated in the adhesion process and we characterized their expression during the replication cycle of the bacteria. In addition, we demonstrated that the Waddlia Pmp-like autotransporter as well as OmpA2 and OmpA3, two members of the extended Waddlia OmpA protein family, exhibit adhesive properties on epithelial cells. We hypothesize that the large diversity of the OmpA protein family is linked to the wide host range of these bacteria that are able to enter and multiply in various host cells ranging from protozoa to mammalian and fish cells

F ry Infrared Spectrometer for Single Shot Analysis of Protein Dynamics

Current submillisecond time resolved broad band infrared spectrosco py, one of the most frequently used techniques for studying structure amp; 8722;functionrelationships in life sciences, is typically limited to fast cycling reactions that can berepeated thousands of times with high frequency. Notably, a majority of chemical andbiological processes do not comply with this requirement. For example, the activationof vertebrate rhodopsin, a prototype of many protein receptors in biological organismsthat mediate basic functions of life, including vision, smell, and taste, is irreversible.Here we present a dispersive single shot Fe amp; 769;ry spectrometer setup that extends suchspectroscopy to irreversible and slow cycling systems by exploiting the uniqueproperties of brilliant synchrotron infrared light combined with an advanced focalplane detector array embedded in a dispersive optical concept. We demonstrate oursingle shot method on microbial actinorhodopsin with a slow photocycle and onvertebrate rhodopsin with irreversible activatio

Short Telomeres Induce a DNA Damage Response in Saccharomyces cerevisiae

Telomerase-deficient Saccharomyces cerevisiae cells show a progressive decrease in telomere length. When grown for several days in log phase, the tlc1Δ cells initially display wild-type growth kinetics with subsequent loss of growth potential after which survivors are generated via RAD52-dependent homologous recombination. We found that chromosome loss in these telomerase-deficient cells only increased after a significant decline in growth potential of the culture. At earlier stages of growth, as the telomerase-deficient cells began to show loss of growth potential, the cells arrested in G2/M and showed RNR3 induction and Rad53p phosphorylation. These responses were dependent on RAD24 and MEC1, suggesting that short telomeres are recognized as DNA damage and signal G2/M arrest