New mutations fts-36, lts-33, and ftsW clustered in the mra region of the Escherichia coli chromosome induce thermosensitive cell growth and division.

Three new mutants of Escherichia coli showing thermosensitive cell growth and division were isolated, and the mutations were mapped to the mra region at 2 min on the E. coli chromosome map distal to leuA. Two mutations were mapped closely upstream of ftsI (also called pbpB), in a region of 600 bases; the fts-36 mutant showed thermosensitive growth and formed filamentous cells at 42 degrees C, whereas the lts-33 mutant lysed at 42 degrees C without forming filamentous cells. The mutation in the third new thermosensitive, filament-forming mutant, named ftsW, was mapped between murF and murG. By isolation of these three mutants, about 90% of the 17-kilobase region from fts-36-lts-33 to envA could be filled with genes for cell division and growth, and the genes could be aligned.     

GeneTrack--a genomic data processing and visualization framework

MOTIVATION: High-throughput 'ChIP-chip' and 'ChIP-seq' methodologies generate sufficiently large data sets that analysis poses significant informatics challenges, particularly for research groups with modest computational support. To address this challenge, we devised a software platform for storing, analyzing and visualizing high resolution genome-wide binding data. GeneTrack automates several steps of a typical data processing pipeline, including smoothing and peak detection, and facilitates dissemination of the results via the web. Our software is freely available via the Google Project Hosting environment at http://genetrack.googlecode.com     

RNase G-dependent degradation of the eno mRNA encoding a glycolysis enzyme enolase in Escherichia coli

Escherichia coli RNase G, encoded by the rng gene, is involved in the processing of 16S rRNA and degradation of the adhE mRNA encoding a fermentative alcohol dehydrogenase. In a search for the intracellular target RNAs of RNase G other than the 16S rRNA precursor and adhE mRNA, total cellular proteins from rng+ and rng::cat cells were compared by two-dimensional gel electrophoresis. The amount of enolase encoded by the eno gene reproducibly increased two- to three-fold in the rng::cat mutant strain compared with the rng+ parent strain. Rifampicin chase experiments showed that the half-life of the eno mRNA was some 3 times longer in the rng::cat mutant than in the wild type. These results indicate that the eno mRNA was a substrate of RNase G in vivo, in addition to 16S rRNA precursor and adhE mRNA.     

Domains in tropoelastin that mediate elastin deposition in vitro and in vivo

Elastic fiber assembly is a complicated process involving multiple different proteins and enzyme activities. However, the specific protein-protein interactions that facilitate elastin polymerization have not been defined. To identify domains in the tropoelastin molecule important for the assembly process, we utilized an in vitro assembly model to map sequences within tropoelastin that facilitate its association with fibrillin-containing microfibrils in the extracellular matrix. Our results show that an essential assembly domain is located in the C-terminal region of the molecule, encoded by exons 29-36. Fine mapping studies using an exon deletion strategy and synthetic peptides identified the hydrophobic sequence in exon 30 as a major functional element in this region and suggested that the assembly process is driven by the propensity of this sequence to form beta-sheet structure. Tropoelastin molecules lacking the C-terminal assembly domain expressed as transgenes in mice did not assemble nor did they interfere with assembly of full-length normal mouse elastin. In addition to providing important information about elastin assembly in general, the results of this study suggest how removal or alteration of the C terminus through stop or frameshift mutations might contribute to the elastin-related diseases supravalvular aortic stenosis and cutis laxa.     

RNase ES of Streptomyces coelicolor A3(2) can complement the rne and rng mutations in Escherichia coli

The Streptomyces coelicolor gene SCC88.10c encodes a protein (RNase ES) which is homologous to endoribonucleases in the RNase E/G family. We expressed S. coelicolor RNase ES as a 6 x His-tagged protein in an Escherichia coli mutant carrying a rng (which encodes RNase G) or a rne (which encodes RNase E) mutation to study whether S. coelicolor RNase ES is able to complement these mutations in host E. coli cells. The results clearly indicated that the S. coelicolor RNase ES can partially abrogate either the rng::cat or rne-1 mutation, as measured by the ability to suppress the several aberrant phenotypes resulting from the rng or rne mutation. Thus, S. coelicolor RNase ES appears to have the dual ability to supplant the functions of both RNase G and RNase E in E. coli.     

Design, synthesis and structure-activity relationship studies of novel indazole analogues as DNA gyrase inhibitors with Gram-positive antibacterial activity

In this study, we report the design, synthesis and structure-activity relationships of novel indazole derivatives as DNA gyrase inhibitors with Gram-positive antibacterial activity. Our results show that selected compounds from this series exhibit potent antibacterial activity against Gram-positive bacteria including multi-drug resistant strains that is methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VRE).     

Synthesis and antibacterial activity of novel and potent DNA gyrase inhibitors with azole ring

The 4-piperidyl moiety and the pyrazole ring in 1-(3-chlorophenyl)-5-(4-phenoxyphenyl)-3-(4-piperidyl)pyrazole 2, which has previously shown improved DNA gyrase inhibition and target-related antibacterial activity, were transformed to other groups and the in vitro antibacterial activity of the synthesized compounds was evaluated. The selected pyrazole, oxazole and imidazole derivatives showed moderate inhibition against DNA gyrase and topoisomerase IV with similar IC(50) values (IC(50)=9.4-25 microg/mL). In addition, many of the pyrazole, oxazole and imidazole derivatives synthesized in this study exhibited potent antibacterial activity against quinolone-resistant clinical isolates and coumarin-resistant laboratory isolates of Gram-positive bacteria with minimal inhibitory concentration values equivalent to those against susceptible strains.     

Functional relationship between Escherichia coli RNase E and the CafA protein

We analyzed the functional relationship between the Escherichia coli RNase E and the CafA protein, which show extensive sequence similarity. The temperature-sensitive growth of the RNase E mutant strain ams1 was partially suppressed by multicopy plasmids bearing the cafA gene. Introduction of a cafA::cat mutation enhanced the temperature sensitivity of the ams1 mutant. These results suggest that there is a functional homology between these two proteins. Received: 17 May 1996 / Accepted: 1 October 1996