A Novel Endogenous Induction of ColE7 Expression in a csrA Mutant of Escherichia coli

2012 ◽  
Vol 66 (4) ◽  
pp. 392-397 ◽  
Author(s):  
Hao-Wei Chang ◽  
Tsung-Yeh Yang ◽  
Guang-Sheng Lei ◽  
Kin-Fu Chak
Keyword(s):  
Escherichia Coli ◽  
Endogenous Induction

scholarly journals Glucose- and Glucokinase-Controlled mal Gene Expression in Escherichia coli

2008 ◽  
Vol 191 (3) ◽  
pp. 701-712 ◽  
Author(s):  
Christina Lengsfeld ◽  
Stefan Schönert ◽  
Renate Dippel ◽  
Winfried Boos
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Gene Regulation ◽  
Glucose Transporter ◽  
Direct Interaction ◽  
Transcriptional Activator ◽  
Structural Similarity ◽  
Expression In Escherichia Coli ◽  
Maltodextrin Phosphorylase ◽  
Endogenous Induction

ABSTRACTMalT is the central transcriptional activator of allmalgenes inEscherichia coli. Its activity is controlled by the inducer maltotriose. It can be inhibited by the interaction with certain proteins, and its expression can be controlled. We report here a novel aspect ofmalgene regulation: the effect of cytoplasmic glucose and glucokinase (Glk) on the activity and the expression of MalT. Amylomaltase (MalQ) is essential for the metabolism of maltose. It forms maltodextrins and glucose from maltose or maltodextrins. We found that glucose above a concentration of 0.1 mM blocked the activity of the enzyme.malQmutants when grown in the absence of maltodextrins are endogenously induced by maltotriose that is derived from the degradation of glycogen. Therefore, the fact thatglk malQ+mutants showed elevatedmalgene expression finds its explanation in the reduced ability to remove glucose from MalQ-catalyzed maltodextrin formation and is caused by a metabolically induced MalQ−phenotype. However, even in mutants lacking glycogen, Glk controls endogenous induction. We found that overexpressed Glk due to its structural similarity with Mlc, the repressor ofmalT, binds to the glucose transporter (PtsG), releasing Mlc and thus increasingmalTrepression. In addition, even in mutants lacking Mlc (and glycogen), the overexpression ofglkleads to a reduction inmalgene expression. We interpret this repression by a direct interaction of Glk with MalT concomitant with MalT inhibition. This repression was dependent on the presence of either maltodextrin phosphorylase or amylomaltase and led to the inactivation of MalT.

scholarly journals The Maltodextrin System of Escherichia coli: Glycogen-Derived Endogenous Induction and Osmoregulation

2005 ◽  
Vol 187 (24) ◽  
pp. 8332-8339 ◽  
Author(s):  
Renate Dippel ◽  
Tobias Bergmiller ◽  
Alex Böhm ◽  
Winfried Boos
Keyword(s):  
Escherichia Coli ◽  
Gene Encoding ◽  
High Osmolarity ◽  
High Level ◽  
Maltodextrin Phosphorylase ◽  
Endogenous Induction

ABSTRACT Strains of Escherichia coli lacking MalQ (maltodextrin glucanotransferase or amylomaltase) are endogenously induced for the maltose regulon by maltotriose that is derived from the degradation of glycogen (glycogen-dependent endogenous induction). A high level of induction was dependent on the presence of MalP, maltodextrin phosphorylase, while expression was counteracted by MalZ, maltodextrin glucosidase. Glycogen-derived endogenous induction was sensitive to high osmolarity. This osmodependence was caused by MalZ. malZ, the gene encoding this enzyme, was found to be induced by high osmolarity even in the absence of MalT, the central regulator of all mal genes. The osmodependent expression of malZ was neither RpoS nor OmpR dependent. In contrast, the malPQ operon, whose expression was also increased at a high osmolarity, was partially dependent on RpoS. In the absence of glycogen, residual endogenous induction of the mal genes that is sensitive to increasing osmolarity can still be observed. This glycogen-independent endogenous induction is not understood, and it is not affected by altering the expression of MalP, MalQ, and MalZ. In particular, its independence from MalZ suggests that the responsible inducer is not maltotriose.

Structural organization of escherichia coli ribosomes as determined by immuno electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 166-167 ◽  
Author(s):  
G. Stöffler ◽  
R.W. Bald ◽  
J. Dieckhoff ◽  
H. Eckhard ◽  
R. Lührmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Ribosomal Subunit ◽  
Spatial Arrangement ◽  
Small Subunit ◽  
Antibody Binding ◽  
Immuno Electron Microscopy

A central step towards an understanding of the structure and function of the Escherichia coli ribosome, a large multicomponent assembly, is the elucidation of the spatial arrangement of its 54 proteins and its three rRNA molecules. The structural organization of ribosomal components has been investigated by a number of experimental approaches. Specific antibodies directed against each of the 54 ribosomal proteins of Escherichia coli have been performed to examine antibody-subunit complexes by electron microscopy. The position of the bound antibody, specific for a particular protein, can be determined; it indicates the location of the corresponding protein on the ribosomal surface.The three-dimensional distribution of each of the 21 small subunit proteins on the ribosomal surface has been determined by immuno electron microscopy: the 21 proteins have been found exposed with altogether 43 antibody binding sites. Each one of 12 proteins showed antibody binding at remote positions on the subunit surface, indicating highly extended conformations of the proteins concerned within the 30S ribosomal subunit; the remaining proteins are, however, not necessarily globular in shape (Fig. 1).

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

Infection of Escherichia coli with bacteriophages

1969 ◽  
Vol 27 ◽  
pp. 370-371
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Nucleic Acid ◽  
Cell Surface ◽  
Virus Type ◽  
Infection Process ◽  
Adsorption Site ◽  
The Other ◽  
Specific Receptors ◽  
Bacterial Receptors

The first step in the infection of a bacterium by a virus consists of a collision between cell and bacteriophage. The presence of virus-specific receptors on the cell surface will trigger a number of events leading eventually to release of the phage nucleic acid. The execution of the various "steps" in the infection process varies from one virus-type to the other, depending on the anatomy of the virus. Small viruses like ØX 174 and MS2 adsorb directly with their capsid to the bacterial receptors, while other phages possess attachment organelles of varying complexity. In bacteriophages T3 (Fig. 1) and T7 the small conical processes of their heads point toward the adsorption site; a welldefined baseplate is attached to the head of P22; heads without baseplates are not infective.

The Nature of the Intramembrane Particle

1980 ◽  
Vol 38 ◽  
pp. 688-691
Author(s):  
A.J. Verkleij
Keyword(s):  
Escherichia Coli ◽  
Tight Junction ◽  
Gap Junction ◽  
The Other ◽  
Fracture Face ◽  
Band 3 Protein ◽  
Satisfactory Explanation ◽  
Freeze Fracturing ◽  
Intramembrane Particle ◽  
Luminal Membrane

Freeze-fracturing splits membranes into two helves, thus allowing an examination of the membrane interior. The 5-10 rm particles visible on both monolayers are widely assumed to be proteinaceous in nature. Most membranes do not reveal impressions complementary to particles on the opposite fracture face, if the membranes are fractured under conditions without etching. Even if it is considered that shadowing, contamination or fracturing itself might obscure complementary pits', there is no satisfactory explanation why under similar physical circimstances matching halves of other membranes can be visualized. A prominent example of uncomplementarity is found in the erythrocyte manbrane. It is wall established that band 3 protein and possibly glycophorin represents these nonccmplanentary particles. On the other hand a number of membrane types show pits opposite the particles. Scme well known examples are the ";gap junction',"; tight junction, the luminal membrane of the bladder epithelial cells and the outer membrane of Escherichia coli.

Sign in / Sign up

Export Citation Format

Share Document