|
|
|
|
|
|
Genetic Analysis of Phenoxyalkanoic Acid Degradation in Sphingomonas herbicidovorans MH. Tina A. Müller, 2004.Phenoxyalkanoic acid degradation is well studied in Beta- and Gammaproteobacteria, but the genetic background has not been elucidated so far in Alphaproteobacteria . We report the isolation of several genes involved in dichlor- and mecoprop degradation from the alphaproteobacterium Sphingomonas herbicidovorans MH and propose that the degradation proceeds analogously to that previously reported for 2,4-dichlorophenoxyacetic acid (2,4-D) . Two genes for  -ketoglutarate-dependent dioxygenases, sdpAMH and rdpAMH, were found, both of which were adjacent to sequences with potential insertion elements . Furthermore, a gene for a dichlorophenol hydroxylase (tfdB), a putative regulatory gene (cadR), two genes for dichlorocatechol 1,2-dioxygenases (dccAI/II), two for dienelactone hydrolases (dccDI/II), part of a gene for maleylacetate reductase (dccE), and one gene for a potential phenoxyalkanoic acid permease were isolated . In contrast to other 2,4-D degraders, the sdp, rdp, and dcc genes were scattered over the genome and their expression was not tightly regulated . No coherent pattern was derived on the possible origin of the sdp, rdp, and dcc pathway genes . rdpAMH was 99% identical to rdpAMC1, an (R)-dichlorprop/-ketoglutarate dioxygenase from Delftia acidovorans MC1, which is evidence for a recent gene exchange between Alpha- and Betaproteobacteria . Conversely, DccAI and DccAII did not group within the known chlorocatechol 1,2-dioxygenases, but formed a separate branch in clustering analysis . This suggests a different reservoir and reduced transfer for the genes of the modified ortho-cleavage pathway in Alphaproteobacteria compared with the ones in Beta- and Gammaproteobacteria .
Translational Features of Human Alpha 2b Interferon Production in Escherichia coli. C. A. Valente, 2004. Haemophilus influenzae Rd Lacks a Stringently Conserved Fatty Acid Biosynthetic Enzyme and Thermal Control of Membrane Lipid Composition. Haihong Wang, 2003.The organization of the fatty acid synthetic genes of Haemophilus influenzae Rd is remarkably similar to that of the paradigm organism, Escherichia coli K-12, except that no homologue of the E . coli fabF gene is present . This finding is unexpected, since fabF is very widely distributed among bacteria and is thought to be the generic 3-ketoacyl-acyl carrier protein (ACP) synthase active on long-chain-length substrates . However, H . influenzae Rd contains a homologue of the E . coli fabB gene, which encodes a 3-ketoacyl-ACP synthase required for unsaturated fatty acid synthesis, and it seemed possible that the H . influenzae FabB homologue might have acquired the functions of FabF . E . coli mutants lacking fabF function are unable to regulate the compositions of membrane phospholipids in response to growth temperature . We report in vivo evidence that the enzyme encoded by the H . influenzae fabB gene has properties essentially identical to those of E . coli FabB and lacks FabF activity . Therefore, H . influenzae grows without FabF function . Moreover, as predicted from studies of the E . coli fabF mutants, H . influenzae is unable to change the fatty acid compositions of its membrane phospholipids with growth temperature . We also demonstrate that the fabB gene of Vibrio cholerae El Tor N16961 does not contain a frameshift mutation as was previously reported .
|
© 2005
Transgalactic Ltd (manufacturer of Bioscreen C software) |
Privacy Statement | P.O. Box
1393, 00101 Helsinki, Finland,
Last modified: May 25, 2005
| ||||||
