, 1992; Mayer et al., 1993; Igietseme et al., 1998). Removal of the substrate l-arginine (which would be degraded to Selleck CH5424802 agmatine and pumped back into the cytosol in counter exchange for arginine by AaxC) could therefore promote Chlamydia survival and/or fitness, particularly in strains that are known to infect and replicate within these specialized host cells, such as C. pneumoniae and C. psittaci (Wyrick & Brownridge, 1978; Redecke
et al., 1998). The timing of cleavage, and presumably corresponding activity, of AaxB in these strains may correlate with optimal iNOS activation in infected macrophages and ultimately allow Chlamydia to avoid the detrimental consequences of NO production prior to bacterial exit from the host cell. Alternatively, the presence of processed AaxB in EBs may indicate that EBs are ‘preloaded’ with functional AaxB that is used to protect against NO production during the immediate early stage of infection. This study was supported by grants Selleckchem Y27632 AI44033 from the National Institute of Allergy and Infectious
Diseases (Maurelli), 1F32AI078655-01 from the National Institute of Allergy and Infectious Diseases (Fisher), and the USUHS Graduate Education Office (Bliven). The opinions or assertions contained herein are the private ones of the authors and are not to be construed as official or as reflecting the views of the Department of Defense or the Uniformed Services University. K.A.B. and D.J.F. contributed equally to this work. “
“Expression of adhesin to collagen of Enterococcus faecalis (ace), a known virulence factor, is increased by environmental signals such as the presence of serum, P-type ATPase high temperature, and bile salts. Currently, the enterococcal regulator of survival (Ers) of E. faecalis strain JH2-2 is the only reported repressor of ace. Here, we show that for strain OG1RF, Ers is not involved in the regulation of ace. Our data showed similar levels of ace expression by OG1RF and its Δers derivative in the presence of bile salts, serum, and high temperature. Using ace promoter-lacZ fusions and site-directed mutagenesis,
we confirmed these results and further showed that, while the previously designated Ers box is important for increased expression from the ace promoter of OG1RF, the region responsible for the increase is bigger than the Ers box. In summary, these results indicate that, in strain OG1RF, Ers is not a repressor of ace expression. Although JH2-2 and OG1RF differ by six nucleotides in the region upstream of ace as well as in production of Fsr and gelatinase, the reason(s) for the difference in ace expression between JH2-2 and OG1RF and for increased ace expression in bile, serum and at 46 °C remain(s) to be determined. “
“Mycobacterium smegmatis contains three chaperonin (cpn60) genes homologous to the Escherichia coli groEL gene. One of these (cpn60.
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