scholarly journals Structure of the Capsid Size-Determining Scaffold of “Satellite” Bacteriophage P4

Viruses ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 953
Author(s):  
James L. Kizziah ◽  
Cynthia M. Rodenburg ◽  
Terje Dokland
Keyword(s):  
Escherichia Coli ◽  
Life Cycle ◽  
Mobile Genetic Element ◽  
Gene Products ◽  
Genetic Element ◽  
Size Change ◽  
Capsid Formation ◽  
High Resolution Structure ◽  
Bacteriophage P4 ◽  
Resolution Structure

P4 is a mobile genetic element (MGE) that can exist as a plasmid or integrated into its Escherichia coli host genome, but becomes packaged into phage particles by a helper bacteriophage, such as P2. P4 is the original example of what we have termed “molecular piracy”, the process by which one MGE usurps the life cycle of another for its own propagation. The P2 helper provides most of the structural gene products for assembly of the P4 virion. However, when P4 is mobilized by P2, the resulting capsids are smaller than those normally formed by P2 alone. The P4-encoded protein responsible for this size change is called Sid, which forms an external scaffolding cage around the P4 procapsids. We have determined the high-resolution structure of P4 procapsids, allowing us to build an atomic model for Sid as well as the gpN capsid protein. Sixty copies of Sid form an intertwined dodecahedral cage around the T = 4 procapsid, making contact with only one out of the four symmetrically non-equivalent copies of gpN. Our structure provides a basis for understanding the sir mutants in gpN that prevent small capsid formation, as well as the nms “super-sid” mutations that counteract the effect of the sir mutations, and suggests a model for capsid size redirection by Sid.

scholarly journals High-resolution structure of the alcohol dehydrogenase domain of the bifunctional bacterial enzyme AdhE

2020 ◽  
Vol 76 (9) ◽  
pp. 414-421
Author(s):  
Liyana Azmi ◽  
Eilis C. Bragginton ◽  
Ian T. Cadby ◽  
Olwyn Byron ◽  
Andrew J. Roe ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Alcohol Dehydrogenase ◽  
Aldehyde Dehydrogenase ◽  
X Ray ◽  
X Ray Scattering ◽  
Bacterial Enzyme ◽  
High Resolution Structure ◽  
Resolution Structure

The bifunctional alcohol/aldehyde dehydrogenase (AdhE) comprises both an N-terminal aldehyde dehydrogenase (AldDH) and a C-terminal alcohol dehydrogenase (ADH). In vivo, full-length AdhE oligomerizes into long oligomers known as spirosomes. However, structural analysis of AdhE is challenging owing to the heterogeneity of the spirosomes. Therefore, the domains of AdhE are best characterized separately. Here, the structure of ADH from the pathogenic Escherichia coli O157:H7 was determined to 1.65 Å resolution. The dimeric crystal structure was confirmed in solution by small-angle X-ray scattering.

scholarly journals IS1397 Is Active for Transposition into the Chromosome of Escherichia coli K-12 and Inserts Specifically into Palindromic Units of Bacterial Interspersed Mosaic Elements

1999 ◽  
Vol 181 (22) ◽  
pp. 6929-6936 ◽  
Author(s):  
Jean-Marie Clément ◽  
Caroline Wilde ◽  
Sophie Bachellier ◽  
Patricia Lambert ◽  
Maurice Hofnung
Keyword(s):  
Escherichia Coli ◽  
Mobile Genetic Element ◽  
Basic Element ◽  
Genetic Element ◽  
Repeated Element ◽  
E Coli ◽  
Intergenic Regions ◽  
Natural Isolates ◽  
K 12

ABSTRACT We demonstrate that IS1397, a putative mobile genetic element discovered in natural isolates of Escherichia coli, is active for transposition into the chromosome of E. coliK-12 and inserts specifically into palindromic units, also called repetitive extragenic palindromes, the basic element of bacterial interspersed mosaic elements (BIMEs), which are found in intergenic regions of enterobacteria closely related to E. coli andSalmonella. We could not detect transposition onto a plasmid carrying BIMEs. This unprecedented specificity of insertion into a well-characterized chromosomal intergenic repeated element and its evolutionary implications are discussed.

scholarly journals High-resolution structure of the Escherichia coli ribosome

2015 ◽  
Vol 22 (4) ◽  
pp. 336-341 ◽  
Author(s):  
Jonas Noeske ◽  
Michael R Wasserman ◽  
Daniel S Terry ◽  
Roger B Altman ◽  
Scott C Blanchard ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Resolution ◽  
High Resolution Structure ◽  
Resolution Structure

scholarly journals Recombination between chromosomal IS200 elements supports frequent duplication formation in Salmonella typhimurium.

Genetics ◽  
1995 ◽  
Vol 141 (4) ◽  
pp. 1245-1252 ◽  
Author(s):  
K R Haack ◽  
J R Roth
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Mobile Genetic Element ◽  
Repetitive Sequences ◽  
Mobile Genetic Elements ◽  
Genomic Variation ◽  
Chromosome Rearrangements ◽  
Genetic Element ◽  
High Frequencies ◽  
Typhimurium Strain

Abstract Spontaneous tandem chromosomal duplications are common in populations of Escherichia coli and Salmonella typhimurium. They range in frequency for a given locus from 10(-2) to 10(-4) and probably form by RecA-dependent unequal sister strand exchanges between repetitive sequences in direct order. Certain duplications have been observed previously to confer a growth advantage under specific selective conditions. Tandem chromosomal duplications are unstable and are lost at high frequencies, representing a readily reversible source of genomic variation. Six copies of a small mobile genetic element IS200 are evenly distributed around the chromosome of S. typhimurium strain LT2. A survey of 120 independent chromosomal duplications (20 for each of six loci) revealed that recombination between IS200 elements accounted for the majority of the duplications isolated for three of the loci tested. Duplications of the his operon were almost exclusively due to recombination between repeated IS200 elements. These data add further support to the idea that mobile genetic elements provide sequence repeats that play an important role in recombinational chromosome rearrangements, which may contribute to adaptation of bacteria to stressful conditions.

High-resolution structure determination by ALCHEMI

1983 ◽  
Vol 41 ◽  
pp. 178-181 ◽  
Author(s):  
Peter G. Self ◽  
Peter R. Buseck
Keyword(s):  
Site Occupancy ◽  
Real Space ◽  
Unit Cell ◽  
Bragg Angle ◽  
Electron Current ◽  
High Resolution Structure ◽  
Beam Incident ◽  
Crystallographic Planes ◽  
Electron Beam Incident ◽  
Resolution Structure

ALCHEMI (Atom Location by CHanneling Enhanced Microanalysis) enables the site occupancy of atoms in single crystals to be determined. In this article the fundamentals of the method for both EDS and EELS will be discussed. Unlike HRTEM, ALCHEMI does not place stringent resolution requirements on the microscope and, because EDS clearly distinguishes between elements of similar atomic number, it can offer some advantages over HRTEM. It does however, place certain constraints on the crystal. These constraints are: a) the sites of interest must lie on alternate crystallographic planes, b) the projected charge density on the alternate planes must be significantly different, and c) there must be at least one atomic species that lies solely on one of the planes.An electron beam incident on a crystal undergoes elastic scattering; in reciprocal space this is seen as a diffraction pattern and in real space this is a modulation of the electron current across the unit cell. When diffraction is strong (i.e., when the crystal is oriented near to the Bragg angle of a low-order reflection) the electron current at one point in the unit cell will differ significantly from that at another point.

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