Polypeptide Chain Initiation and the Characterization of Ribosomal Binding Sites in E. coli

1966 ◽  
Vol 31 (0) ◽  
pp. 289-295 ◽  
Author(s):  
M. S. Bretscher
Keyword(s):  
Binding Sites ◽  
Polypeptide Chain ◽  
Chain Initiation ◽  
E Coli

scholarly journals Identification of the rrmA Gene Encoding the 23S rRNA m1G745 Methyltransferase in Escherichia coli and Characterization of an m1G745-Deficient Mutant

1998 ◽  
Vol 180 (2) ◽  
pp. 359-365 ◽  
Author(s):  
Claes Gustafsson ◽  
Britt C. Persson
Keyword(s):  
Escherichia Coli ◽  
Polypeptide Chain ◽  
Chain Elongation ◽  
23S Rrna ◽  
Drastic Reduction ◽  
Gene Encoding ◽  
E Coli ◽  
Loosely Coupled ◽  
Rich Media

ABSTRACT An Escherichia coli mutant lacking the modified nucleotide m1G in rRNA has previously been isolated (G. R. Björk and L. A. Isaksson, J. Mol. Biol. 51:83–100, 1970). In this study, we localize the position of the m1G to nucleotide 745 in 23S rRNA and characterize a mutant deficient in this modification. This mutant shows a 40% decreased growth rate in rich media, a drastic reduction in loosely coupled ribosomes, a 20% decreased polypeptide chain elongation rate, and increased resistance to the ribosome binding antibiotic viomycin. TherrmA gene encoding 23S rRNA m1G745 methyltransferase was mapped to bp 1904000 on the E. colichromosome and identified to be identical to the previously sequenced gene yebH.

Protein Unfolding and Degradation by the CLP Family of Proteases

1998 ◽  
Vol 4 (S2) ◽  
pp. 978-979
Author(s):  
Martin Kessel ◽  
Fabienne Beuron ◽  
Frank Booy ◽  
Eva Kocsis ◽  
Michael Maurizi ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Protein Degradation ◽  
Binding Sites ◽  
Protein Unfolding ◽  
Polypeptide Chain ◽  
Regulatory Protein ◽  
Eukaryotic Cells ◽  
Remarkable Similarity ◽  
E Coli ◽  
Macromolecular Assemblies

ATP-dependent proteases play a major role in regulatory protein degradation in both prokaryotic and eukaryotic cells. ATP-dependent proteases in E. coli fall into two classes. The first class requires the interaction of structurally separate proteases with an ATPase, whereas in the second class both the protease and ATPase are formed from regions of the same polypeptide chain. We have studied the structure of several of these protein degrading complexes in E. coli and have found a remarkable similarity in the architecture of these macromolecular assemblies.The prototypical protease of the first class has as its proteolytic component ClpP, a 14 subunit (MW 21,500) complex arranged as two lOnm-diameter stacked rings of seven subunits each. ClpP can interact with either one of two ATPases, ClpA or ClpX, each with unique substrate specificity. ClpA has two ATP-binding sites per subunit (MW 84,000), and its subunits are arranged as a 13nm (diameter) hexameric ring (MW -500,000).

scholarly journals Essential histidine pairs indicate conserved haem binding in epsilonproteobacterial cytochrome c haem lyases

Microbiology ◽  
2010 ◽  
Vol 156 (12) ◽  
pp. 3773-3781 ◽  
Author(s):  
Melanie Kern ◽  
Juliane Scheithauer ◽  
Robert G. Kranz ◽  
Jörg Simon
Keyword(s):  
Binding Sites ◽  
Cytoplasmic Membrane ◽  
Covalent Attachment ◽  
Amino Acid Residues ◽  
Binding Motifs ◽  
Histidine Residues ◽  
E Coli ◽  
Coordination Sites ◽  
Membrane Bound

Bacterial cytochrome c maturation occurs at the outside of the cytoplasmic membrane, requires transport of haem b across the membrane, and depends on membrane-bound cytochrome c haem lyase (CCHL), an enzyme that catalyses covalent attachment of haem b to apocytochrome c. Epsilonproteobacteria such as Wolinella succinogenes use the cytochrome c biogenesis system II and contain unusually large CCHL proteins of about 900 amino acid residues that appear to be fusions of the CcsB and CcsA proteins found in other bacteria. CcsBA-type CCHLs have been proposed to act as haem transporters that contain two haem b coordination sites located at different sides of the membrane and formed by histidine pairs. W. succinogenes cells contain three CcsBA-type CCHL isoenzymes (NrfI, CcsA1 and CcsA2) that are known to differ in their specificity for apocytochromes and apparently recognize different haem c binding motifs such as CX2CH (by CcsA2), CX2CK (by NrfI) and CX15CH (by CcsA1). In this study, conserved histidine residues were individually replaced by alanine in each of the W. succinogenes CCHLs. Characterization of NrfI and CcsA1 variants in W. succinogenes demonstrated that a set of four histidines is essential for maturing the dedicated multihaem cytochromes c NrfA and MccA, respectively. The function of W. succinogenes CcsA2 variants produced in Escherichia coli was also found to depend on each of these four conserved histidine residues. The presence of imidazole in the growth medium of both W. succinogenes and E. coli rescued the cytochrome c biogenesis activity of most histidine variants, albeit to different extents, thereby implying the presence of two functionally distinct histidine pairs in each CCHL. The data support a model in which two conserved haem b binding sites are involved in haem transport catalysed by CcsBA-type CCHLs.

scholarly journals Cloning and Characterization of Aedes aegypti Trypsin Modulating Oostatic Factor (TMOF) Gut Receptor

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 934
Author(s):  
Dov Borovsky ◽  
Kato Deckers ◽  
Anne Catherine Vanhove ◽  
Maud Verstraete ◽  
Pierre Rougé ◽  
...  
Keyword(s):  
Binding Sites ◽  
Protein Sequence ◽  
Bacterial Cells ◽  
E Coli ◽  
Trypsin Modulating Oostatic Factor ◽  
High Affinity ◽  
Sds Page ◽  
Atpase Inhibitors ◽  
Kinetics Of

Trypsin Modulating Oostatic Factor (TMOF) receptor was solubilized from the guts of female Ae. Aegypti and cross linked to His6-TMOF and purified by Ni affinity chromatography. SDS PAGE identified two protein bands (45 and 61 kDa). The bands were cut digested and analyzed using MS/MS identifying a protein sequence (1306 amino acids) in the genome of Ae. aegypti. The mRNA of the receptor was extracted, the cDNA sequenced and cloned into pTAC-MAT-2. E. coli SbmA− was transformed with the recombinant plasmid and the receptor was expressed in the inner membrane of the bacterial cell. The binding kinetics of TMOF-FITC was then followed showing that the cloned receptor exhibits high affinity to TMOF (KD = 113.7 ± 18 nM ± SEM and Bmax = 28.7 ± 1.8 pmol ± SEM). Incubation of TMOF-FITC with E. coli cells that express the receptor show that the receptor binds TMOF and imports it into the bacterial cells, indicating that in mosquitoes the receptor imports TMOF into the gut epithelial cells. A 3D modeling of the receptor indicates that the receptor has ATP binding sites and TMOF transport into recombinant E. coli cells is inhibited with ATPase inhibitors Na Arsenate and Na Azide.

Sign in / Sign up

Export Citation Format

Share Document