W Boos

..coli...

..Neither sigma S nor trehalose, however, is required for the development of adaptive thermotolerance in growing cells, which might be controlled by sigma E...

..The product of the ugpQ gene, expressed in minicells, has an apparent molecular weight of 17,500. We present evidence that only one major phoB-dependent promoter controls all ugp genes...

..The amino acid sequence deduced for the beginning of the MglA protein showed homology with a family of polypeptides that contain an ATP-binding site and are components of binding-protein-dependent transport systems...

..These strains appeared unstable. Upon reisolation from purified stock cultures kept in glycerol at -20 degrees C, colonies could be isolated that carried only mutant or wild-type protein...

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..MalT, the central activator of the mal genes, is the key element in this complex regulatory network and integrates the different signals to give an appropriate transcriptional response...

..Instead, enzyme IITre-mediated phosphorylation of trehalose requires the activity of enzyme IIAGlc, a component of the major glucose transport system...

..Extracts containing TreC transformed [14C]-maltose into another 14C-labelled compound (preliminarily identified as maltose 1-phosphate) that is likely to be an alternative inducer of the maltose system...

..As Mlc also regulates another operon (manXYZ, see pages 369-379 of this issue), it may very well constitute a new global regulator of carbohydrate utilization...

..This demonstrates that free internal glucose plays an essential role in the formation of the endogenous inducer of the maltose system...

..Upstream to malI we observed a divergent open reading frame that extended to the end of the sequenced DNA...

..It was the MalZ292-associated transferase reaction that allowed the utilization of maltose. In addition, we discovered that mutant and wild type enzyme alike were highly active as gamma-cyclodextrinases...

..We cloned the gene located downstream to PD and found it to strongly repress the expression of the mgl operon. We termed this gene mglD. The presence of D-fucose abolished the repression caused by the plasmid-encoded mglD gene product...

..The control of Mlc activity by sequestration to a transport protein represents a novel form of signal transduction in gene regulation...

..This report corrects our previous view on the function of the treC gene product as an amylotrehalase, which was based on the analysis of the metabolic products of trehalose metabolism in whole cells...

..Other sugars that are not transported by the phosphotransferase system, most notably D-xylose, showed the same effect as glycerol...

..Mutants producing 17-fold more TreF than does the wild type were isolated...

..Specifically, we find helices that are longer than their structurally equivalent counterparts, and fewer internal cavities...

..Nuclease protection experiments revealed a palindromic sequence located directly upstream of the -35 promoter sequence of treB that functions as the operator of the system...

..There is another gene locus near 84 min on the chromosome, that we termed otsR, which is involved in the regulation of otsA/B and possibly otsP. The nature of this regulatory gene is unclear at present...

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..The ratio of the concentrations of trehalose-6-phosphate and trehalose thus is used to switch between the two alternative metabolic uses of trehalose as an osmoprotectant and as a carbon source...

..The GlpF protein appeared in the membrane fraction of plasmid-bearing strains and had an apparent Mr of 25,000...

..Homology to glucosidases, alpha-amylases, and pullulanases were observed. Conserved regions thought to represent active sites in dextrin hydrolases were found in the MalZ protein...

..We conclude that there is an interaction between the glycerol facilitator protein and glycerol kinase that stimulates kinase activity, analogous to the hexokinase- and glycerol kinase-porin interactions in mitochondria...

..Thus, the plasmid carries the structural gene for the periplasmic trehalase and not just a gene involved in the regulation of the enzyme...

..5 mM. Cells had to be starved for Pi in order to observe this inhibition. We conclude that the activity of the Ugp transport system is controlled by the level of internal phosphate...

..The accumulated trehalose is extracted from the bacteria by 70% hot ethanol and can easily be purified radiochemically by chromatographic techniques...

..Also, overproduction of MalT counteracted the Aes-dependent repression, indicating a direct interaction between MalT and Aes...

..Downstream of malS, after a 513-base pair intergenic region, lies the convergently transcribed gene avtA, which codes for the alanine/valine transaminase...

..Using p-nitrophenyl-alpha-D-maltohexaoside as a substrate, we determined a Km of 3 microM and a Vmax of 0.14 mumol/min/mg of protein...

..This is not the case in a malT(Con) strain that expresses the mal genes constitutively. We conclude that malY encodes an enzyme that degrades the inducer of the maltose system or prevents its synthesis...

..Also, the overexpression of plasmid-encoded metC did not affect mal gene expression, nor did the deduced amino acid sequence of MetC show homology to that of MalY...

..litoralis or the soluble engineered protein. The purified native TMBP was identified as a glycoprotein...

..Moreover, assembly of the Tsr protein seems to be closely coupled to its synthesis...

..55, 0.20, 0.07, 0.04. Maltotriose and other oligosaccharides were acetylated with 2% of the rate determined for glucose. The Km for glucose and maltose were 62 and 90 mM, and the Vmax was 0.20 and 0.11 mmol/min x mg enzyme, respectively...

..gldA was cloned, and its position on the physical map of E. coli was determined. The expression of gldA was induced by hydroxyacetone under stationary-phase growth conditions...

..The mutants were more resistant to the hydrophobic antibiotic tetracycline, as well as to the membrane perturbants ethanol and dimethylsulphoxide and to the stress of low-osmolarity medium...

..In contrast, we feel that the enzymatic activity of lacZ fusions is only a limited parameter for studying the topology of a complex membrane protein...

..The phenotype of this mutant indicated that trehalose-6-phosphate is the effective in vivo inducer of the system...

..Bacteriol. 170:2136-2142, 1988) originated from the 88-min region of the Escherichia coli chromosome and not, as reported, from the 7-min region and that the gene product identified as MvrA is in fact encoded by a gene distal to glpX...

..The crystals belong to the monoclinic space group C2, with unit-cell parameters a = 106.5, b = 150.5, c = 170.1 A, beta = 107.8 degrees. A native data set has been obtained at a resolution of 5 A...

..In addition, recent experimental evidence suggests that regulation of gene expression and transport activity is far more complex than expected...

..The synthesis of the remaining polypeptide of 30,000 prevented the proper assembly of other transport related binding proteins such as the ribose- and galactose-binding protein...

..Therefore, we propose that a direct protein-protein interaction with MalT, the central transcriptional activator of the maltose system, underlies MalY-dependent repression of the maltose system...

..This model suggests that bacteria may be able to couple information about extracellular substrate availability to the transcriptional apparatus via the levels of ATP hydrolysis associated with transport...

..A half-maximal chemotactic response occurred at 25% of the malE+ MBP level, suggesting that in vivo the KD for binding of maltose-loaded MBP to Tar is quite high (approximately 250 microM)...

..Together, these results establish that MalY acts directly upon MalT without the help of any factor, and that MalY is a negative effector of MalT competing with the inducer for MalT binding...

..These properties differentiate this periplasmic enzyme from the cytoplasmic amylomaltase and define it as an alpha-amylase...

..The structure and its relationship to function are discussed in the light of known mutations from the homologous Escherichia coli and Salmonella typhimurium proteins...

..coli linkage map. A Tn10 insertion in malI also resulted in the loss of constitutivity at low osmolarity and delayed the induction of the maltose regulon by exogenous inducers...

..The sequences of the proteins contain the characteristics of several other binding protein-dependent transport systems, but they seem to be particularly closely related to the maltose system...

..The repression at high osmolarity no longer occurred in malQ mutants, however, provided that glycogen was present...

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..coli. The predicted amino acid sequence of the encoded proteins showed 90% or more identity in every pairwise comparison of species...

..The present report demonstrates that it is not the gene product of glpT and is not required for active transport of sn-glycerol-3-phosphate...

..Excess MalK competed with the MalK-LacZ hybrid protein for sites in the membrane and resulted in the hybrid fractionating as a soluble protein.(ABSTRACT TRUNCATED AT 400 WORDS)..

..coli linkage map. Complementation analysis using these mutants revealed only one complementation group. Thus, one gene is necessary and sufficient for the proton motive force-dependent sn-glycerol-3-phosphate transport system...

..These conserved regions include residues implicated in amino-acid binding...

..Both systems were inversely controlled by internal Pi. Whereas the Ugp system was inhibited, the GlpT system was stimulated by elevated internal Pi...

..It is not regulated by D-fucose, the inducer of the mgl system and mutants defective in cir are unimpaired in the uptake of substrates of the mgl-dependent transport system...

..These three genes were present in an operon transcribed in the order glpA glpC glpB in the clockwise direction on the linkage map of E. coli...

..We conclude that our previously published sequence of markers was incorrect and is in fact inverted. The present data indicate the following sequence of markers in clockwise order: his gat cdd mgl cir fpk gyrA...

..e., 46 of the 146 amino acids are Gln or Asn. This polypeptide and the UgpQ protein were identified in an in vitro transcription/translation system as proteins with apparent molecular weights of 19.5 and 27 kDa, respectively...

..These findings indicate how catabolite repression may be mediated but do not explain its physiological significance in glycerol metabolism...

..No gene products could be assigned to the ugpA and ugpD genes. Hybridization experiments allowed the physical characterization of 20 kb of DNA adjacent to the ugp genes on the E. coli chromosome including the liv genes...

..Using ugp-lacZ fusions, it could be shown that the ugp region consists of at least two different operons that are transcribed in the same direction (counterclockwise) on the E. coli chromosome...

..Analysis of proteins labeled in minicells harboring either glpR+ recombinant plasmids or a glpR::Tn5 derivative showed that the glpR gene product is a protein with an apparent molecular weight of 33,000...

..The substrates of the phosphodiesterase had no affinity for the glpT-encoded active transport system. Thus, the glpQ gene product expands the catabolic capability of the glp regulon to include a variety of glycerophosphodiesters...

..It is either the structural gene for the binding protein or located proximal to it. The analysis of the crosses allowed the ordering of the markers in the clockwise direction as follows: aroB, malA, asd, ugpA, ugpB, livH, pit...