|
|
|
|
|
|
The ompU Paralogue vca1008 Is Required for Virulence of Vibrio cholerae. Carlos G. Osorio, 2004.We made single and combined mutations in ompU, ompT, and the two putative porin genes vca1008 and vc0972 . The fitness of the strains was tested in vitro and in the infant mouse model of intestinal infection . We also studied the transcriptional induction of vca1008 in vitro and during mouse infection . We show that vca1008 is induced during infection and is necessary and sufficient (in the absence of ompU, ompT, and vc0972) for infection . Comparative Analysis of the Conventional and Novel pmo (Particulate Methane Monooxygenase) Operons from Methylocystis Strain SC2. Peter Ricke, 2004.In addition to the conventional pmoA gene (pmoA1) encoding the active site polypeptide of particulate methane monooxygenase, a novel pmoA gene copy (pmoA2) is widely distributed among type II methanotrophs (methane-oxidizing bacteria [MOB]) (M . Tchawa Yimga, P . F . Dunfield, P . Ricke, J . Heyer, and W . Liesack, Appl . Environ . Microbiol . 69:5593-5602, 2003) . Here we report that the pmoA1 and pmoA2 gene copies in the type II MOB Methylocystis strain SC2 are each part of a complete pmoCAB gene cluster (pmoCAB1, pmoCAB2) . A bacterial artificial chromosome (BAC) library of strain SC2 genomic DNA was constructed, and BAC clones carrying either pmoCAB1 or pmoCAB2 were identified . Comparative sequence analysis showed that these two gene clusters exhibit low levels of identity at both the DNA level (67.4 to 70.9%) and the derived protein level (59.3 to 65.6%) . In contrast, the secondary structures predicted for PmoCAB1 and PmoCAB2, as well as the derived transmembrane-spanning regions, are nearly identical . This suggests that PmoCAB2 is, like PmoCAB1, a highly hydrophobic, membrane-associated protein . A total of 190 of the 203 amino acid residues representing a highly conserved consensus sequence of the currently known PmoCAB1 and AmoCAB sequence types could be identified in PmoCAB2 . The amoCAB gene cluster encodes ammonia monooxygenase and is evolutionarily related to pmoCAB . Analysis of a set of amino acid residues that allowed differentiation between conventional PmoA and AmoA provided further support for the hypothesis that pmoCAB2 encodes a functional equivalent of PmoCAB1 . In experiments in which we used 5' rapid amplification of cDNA ends we identified transcriptional start sites 320 and 177 bp upstream of pmoC1 and pmoC2, respectively . Immediately upstream of the transcriptional start sites of both pmoCAB1 and pmoCAB2, sequence motifs similar to Escherichia coli  70 promoters were identified .
Enhanced Accumulation of Cd2+ by a Mesorhizobium sp . Transformed with a Gene from Arabidopsis thaliana Coding for Phytochelatin Synthase. Rutchadaporn Sriprang, 2003.We expressed the Arabidopsis thaliana gene for phytochelatin synthase (PCSAt) in Mesorhizobium huakuii subsp . rengei B3, a microsymbiont of Astragalus sinicus, a legume used as manure . The PCSAt gene was expressed under the control of the nifH promoter, which regulates the nodule-specific expression of the nifH gene . The expression of the PCSAt gene was demonstrated in free-living cells under low-oxygen conditions . Phytochelatin synthase (PCS) was expressed and catalyzed the synthesis of phytochelatins [(  -Glu-Cys)n-Gly; PCs] in strain B3 . A range of PCs, with values of n from 2 to 7, was synthesized by cells that expressed the PCSAt gene, whereas no PCs were found in control cells that harbored the empty plasmid . The presence of CdCl2 activated PCS and induced the synthesis of substantial amounts of PCs . Cells that contained PCs accumulated 36 nmol of Cd2+/mg (dry weight) of cells . The expression of the PCSAt gene in M . huakuii subsp . rengei B3 increased the ability of cells to bind Cd2+ approximately 9- to 19-fold . The PCS protein was detected by immunostaining bacteroids of mature nodules of A . sinicus containing the PCSAt gene . When recombinant M . huakuii subsp . rengei B3 established the symbiotic relationship with A . sinicus, the symbionts increased Cd2+ accumulation in nodules 1.5-fold .
|
© 2005
Transgalactic Ltd (manufacturer of Bioscreen C software) |
Privacy Statement | P.O. Box
1393, 00101 Helsinki, Finland,
Last modified: May 25, 2005
| ||||||
