Project description:In Escherichia coli, Lon is an ATP-dependent protease which degrades misfolded proteins and certain rapidly-degraded regulatory proteins. Given that oxidatively damaged proteins are generally degraded rather than repaired, we anticipated that Lon deficient cells would exhibit decreased viability during aerobic, but not anaerobic, carbon starvation. We found that the opposite actually occurs. Wild-type and Lon deficient cells survived equally well under aerobic conditions, but Lon deficient cells died more rapidly than the wild-type under anaerobiosis. Microarray analysis revealed that genes of the Clp family of ATP-dependent proteases were induced during aerobic growth but not during anaerobic growth. Thus, Clp may compensate for loss of Lon when cells are in an oxygen containing atmosphere. Under anaerobic carbon starvation conditions, Lon must be active to support survival. Keywords: Other
Project description:Lon protease plays vital roles in many biological processes in Pseudomonas syringae, including type III secretion systems (T3SS), transcription regulation, protein synthesis and energy metabolism. Lon also functions as a transcriptional regulator in other bacterial species (e.g., Escherichia coli and Brevibacillus thermoruber). Therefore, we hypothesise that Lon has dual functions in P. syringae. To reveal the molecular mechanisms of Lon as a transcriptional regulator and protease under different environmental conditions, we used a combination of transcriptome sequencing (RNA-seq), chromatin immunoprecipitation sequencing (ChIP-seq) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify the genes or proteins regulated by Lon. As a transcriptional regulator, Lon bound to the promoter regions of PSPPH_4788, gacA, fur, gntR, clpS, lon and glyA and consequently regulated 1-dodecanol oxidation activity, motility, pyoverdine production, gluconokinase activity, N-end rule pathway, lon expression and serine hydroxymethyltransferase (SHMT) activity in King’s B medium (KB). In minimal medium (MM), Lon regulated SHMT activity and lon expression by binding to the promoter regions of glyA and lon, respectively. As a protease, Lon regulated the T3SS and metabolic pathways (e.g., amino acid metabolism). In MM, Lon regulated the polysaccharide metabolic process by controlling PSPPH_0514, AlgA, CysD and PSPPH_4991. Taken together, these data demonstrate that Lon acts as a transcriptional regulator or protease in different environments and tunes its virulence and metabolic functions accordingly.
Project description:Investigation of whole genome gene expression level changes in a Escherichia coli MG1655 K-12 ?fnr mutant, compared to the wild-type strain. The mutations engineered into this strain produce a strain lacking the FNR protein. WT strains were grown under aerobic and anaerobic growth conditions. A six chip study using total RNA recovered from two separate cultures of Escherichia coli MG1655 K-12 WT (aerobic and anaerobic) and two separate cultures of the ?fnr mutant strain (anaerobic). Each chip measures the expression level of 4,661 genes from Escherichia coli MG1655 K-12 with eight 60-mer probes per gene, with each probe represented twice on the array.
Project description:The faecal indicator bacterium Escherichia coli K12 was used to study the cellular events that take place at the transcription level using the microarray technology during short-term (physiological) and long-term (genetic) adaptation to slow growth under limited nutrient supply. Short-term and long-term adaptation were assessed by comparing the mRNA levels isolated after 40 or 500 hours of glucose-limited continuous culture at a dilution rate of 0.3 h-1 with those from batch culture with glucose excess. Keywords: glucose-limited continuous culture, adaptation, microarray, high affinity transport systems, transcriptome, Escherichia coli
Project description:Lon protease is known to regulate various transcriptional regulators in other bacterial organisms. To understand whether lon protease is involved in transcriptional changes in Vibrio cholerae, wholel-genome level transcriptional profiling was performed using custom microarrays. Transcriptomes of lonA mutant and wild-type strains were compared in this study.
Project description:How do bacteria regulate their cellular physiology in response to starvation? Here, we present a detailed characterization of Escherichia coli growth and starvation over a time-course lasting two weeks. We have measured multiple cellular components, including RNA and proteins at deep genomic coverage, as well as lipid modifications and flux through central metabolism. Our study focuses on the physiological response of E. coli to starvation, not on the genetic adaptation of E. coli to utilize alternative nutrients. In our analysis, we have taken advantage of the temporal correlations within and among RNA and protein abundances to identify systematic trends in gene regulation. Specifically, we have developed a general computational strategy for classifying expression-profile time courses into distinct categories in an unbiased manner. We have also developed, from dynamic models of gene expression, a framework to characterize protein degradation patterns based on the observed temporal relationships between mRNA and protein abundances. By comparing and contrasting our transcriptomic and proteomic data, we have identified several broad physiological trends in the E. coli starvation response. Strikingly, mRNAs are widely down-regulated in response to glucose starvation, presumably as a strategy for reducing new protein synthesis. By contrast, protein abundances display more varied responses. The abundances of many proteins involved in energy-intensive processes mirror the corresponding mRNA profiles while proteins involved in nutrient metabolism remain abundant even though their corresponding mRNAs are down-regulated. Time course of E. coli growth and starvation in glucose-limited minimal medium
Project description:This SuperSeries is composed of the following subset Series: GSE5075: Aerobic transcriptional responses of Escherichia coli to NO under defined chemostat conditions. GSE5076: Anaerobic transcriptional responses of Escherichia coli to NO under defined chemostat conditions. GSE5084: Anaerobic NO-exposed Chemostat Comparison of Wt & norR mutant Responses GSE5137: Aerobic NO-exposed Chemostat Comparison of Wt & norR mutant Responses GSE5139: Aerobic NO-exposed Chemostat Comparison of Wt & hmp mutant Responses Keywords: SuperSeries Refer to individual Series
Project description:To investigate mechanism of inosine promotes the survival and metabolism of MDA-MB-231 cells under starvation conditions, MDA-MB-231 cells were treated with inosine and glucose for 12h under starvation conditions. We then performed gene expression profiling analysis using data obtained from RNA-seq of MDA-MB-231 cells under three different treatments(-G-Q,Inosine,Glucose).
Project description:Investigation of whole genome gene expression level changes in a Escherichia coli MG1655 K-12 M-bM-^HM-^Fhns/M-bM-^HM-^FstpA strain from exponental growth under aerobic and anaerobic growth conditions. The results are further described in the article Genome-scale Analysis of E.coli FNR Reveals the Complex Features of Transcrtipion Factor Binding. A four chip study using total RNA recovered from two separate cultures of Escherichia coli MG1655 K-12 M-bM-^HM-^Fhns/M-bM-^HM-^FstpA mutant strain under aerobic and anaerobic growth conditions. Each chip measures the expression level of 4,661 genes from Escherichia coli MG1655 K-12 using a high-density tiling array consisting of ~385,000 60mer probes spaced every 12 bp.
Project description:MYC has been named the quintessential oncogene and is deregulated in the majority of human cancers. Still, finding c-MYC inhibitors for therapeutic use has been problematic and MYC itself has long been viewed as “undruggable”. Here we present a novel strategy for achieving c-MYC inhibition, involving specific bacterial effector molecules. We made the surprising observation that uropathogenic E. coli activate c-MYC degradation and attenuate MYC expression in host cells and tissues. We further identified effector molecules responsible for this effect. The bacterial Lon protease is shown to rapidly degrade c-MYC and therapeutic efficacy is demonstrated in bladder and colon cancer models. Long-term protection, defined by delayed tumor progression, increased survival and low toxicity further supports the therapeutic potential of Lon. These results suggest that bacteria have evolved strategies to control c-MYC tissue levels in the host, which can be exploited to target c-MYC therapeutically in different cancers.