scholarly journals Structural and functional characterization of the Helicobacter pylori cytidine 5'-monophosphate-pseudaminic acid synthase PseF: molecular insight into substrate recognition and catalysis mechanism

2017 ◽  
Vol Volume 10 ◽  
pp. 79-88 ◽  
Author(s):  
Syeda Umme Habiba Wahid
Keyword(s):  
Helicobacter Pylori ◽  
Substrate Recognition ◽  
Functional Characterization ◽  
Catalysis Mechanism ◽  
Pseudaminic Acid ◽  
Insight Into

Functional characterization of the antagonistic flagellar late regulators FliA and FlgM of Helicobacter pylori and their effects on the H. pylori transcriptome

2002 ◽  
Vol 43 (2) ◽  
pp. 307-322 ◽  
Author(s):  
Christine Josenhans ◽  
Eike Niehus ◽  
Stefanie Amersbach ◽  
Andrea Hörster ◽  
Christian Betz ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Functional Characterization ◽  
H Pylori

scholarly journals Structural and functional characterization of mouse U7 small nuclear RNA active in 3' processing of histone pre-mRNA.

1988 ◽  
Vol 8 (4) ◽  
pp. 1518-1524 ◽  
Author(s):  
D Soldati ◽  
D Schümperli
Keyword(s):  
Sea Urchin ◽  
Functional Characterization ◽  
Rnase H ◽  
Primer Extension ◽  
Small Nuclear Rna ◽  
Nuclear Rna ◽  
Processing Signal ◽  
Insight Into

Oligonucleotides derived from the spacer element of the histone RNA 3' processing signal were used to characterize mouse U7 small nuclear RNA (snRNA), i.e., the snRNA component active in 3' processing of histone pre-mRNA. Under RNase H conditions, such oligonucleotides inhibited the processing reaction, indicating the formation of a DNA-RNA hybrid with a functional ribonucleoprotein component. Moreover, these oligonucleotides hybridized to a single nuclear RNA species of approximately 65 nucleotides. The sequence of this RNA was determined by primer extension experiments and was found to bear several structural similarities with sea urchin U7 snRNA. The comparison of mouse and sea urchin U7 snRNA structures yields some further insight into the mechanism of histone RNA 3' processing.

Phylogenetic analysis of fungal aquaporins provides insight into their possible role in water transport of mycorrhizal associations

Botany ◽  
2013 ◽  
Vol 91 (8) ◽  
pp. 495-504 ◽  
Author(s):  
Hao Xu ◽  
Janice E.K. Cooke ◽  
Janusz J. Zwiazek
Keyword(s):  
Water Transport ◽  
Mycorrhizal Fungi ◽  
Functional Characterization ◽  
Arbuscular Mycorrhizal ◽  
Gene Families ◽  
Fungal Species ◽  
Comparative Genomic ◽  
Mycorrhizal Associations ◽  
Insight Into

In mycorrhizal associations, water transport properties of the fungal hyphae may have a profound effect on water transport of the host plant. The importance of aquaporins, water-transporting members of the major intrinsic protein (MIP) family, in facilitating water transport has been widely acknowledged and extensively studied in plants. However, until recently, relatively little was known about the structure, function, and regulation of fungal MIPs. The rapid increase in the number of sequenced fungal genomes, including Laccaria bicolor and other mycorrhizal fungi, has enabled functional and comparative genomic investigations to delineate the role that fungal MIPs play in mycorrhizal-facilitated plant water transport. Phylogenic analysis of 229 fungal MIPs from 88 species revealed that MIPs of mycorrhizal fungal species fall into four clusters delineated by functionally characterized fungal MIPs: the orthodox aquaporins, the aquaglyceroporins, the facultative fungal aquaporins, and the X intrinsic proteins. This comparative genomics analysis, together with in silico structural characterization of predicted MIPs and recently published functional characterization of MIPs from a small number of ectomycorrhizal and arbuscular mycorrhizal species, provide new insight into MIP gene families of mycorrhizal fungi and possible roles for fungal aquaporins in water relations of mycorrhizal plant–fungus symbioses.

scholarly journals PE5-PPE4-EspG3 trimer structure from mycobacterial ESX-3 secretion system gives insight into cognate substrate recognition by ESX systems

2020 ◽  
Author(s):  
Zachary A. Williamson ◽  
Catherine T. Chaton ◽  
William A. Ciocca ◽  
Natalia Korotkova ◽  
Konstantin V. Korotkov
Keyword(s):  
Cell Envelope ◽  
Substrate Recognition ◽  
Secretion System ◽  
Multiple Factors ◽  
Type Vii Secretion ◽  
Shape Complementarity ◽  
Numerous Type ◽  
Unique Shape ◽  
Insight Into

ABSTRACTMycobacterium tuberculosis (Mtb) has evolved numerous type VII secretion (ESX) systems to secrete multiple factors important for both growth and virulence across their cell envelope. Three such systems; ESX-1, ESX-3, and ESX-5; have been shown to each secrete a unique set of substrates. A large class of these substrates secreted by these three systems are the PE and PPE families of proteins. Proper secretion of the PE-PPE proteins requires the presence of EspG, with each system encoding its own unique copy. There is no cross-talk between any of the ESX systems and how each EspG is recognizing its subset of PE-PPE proteins is currently unknown. The only current structural characterization of PE-PPE-EspG trimers is from the ESX-5 system. Here we present the crystal structure of the PE5mt-PPE4mt-EspG3mm trimer, from the ESX-3 system. Our trimer reveals that EspG3mm interacts exclusively with PPE4mt in a similar manner to EspG5, shielding the hydrophobic tip of PPE4mt from solvent. The C-terminal helical domain of EspG3mm is dynamic, alternating between an ‘open’ and ‘closed’ form, and this movement is likely functionally relevant in the unloading of PE-PPE heterodimers at the secretion machinery. In contrast to the previously solved ESX-5 trimers, the PE-PPE heterodimer of our ESX-3 trimer is interacting with it’s chaperone at a drastically different angle, and presents different faces of the PPE protein to the chaperone. We conclude that the PPE-EspG interface from each ESX system has a unique shape complementarity that allows each EspG to discriminate amongst non-cognate PE-PPE pairs.

scholarly journals Discovery and characterization of Hv1-type proton channels in reef-building corals.

2021 ◽  
Author(s):  
Gisela Rangel-Tescas ◽  
Cecilia Cervantes ◽  
Miguel A Cervantes-Rocha ◽  
Esteban Suarez-Delgado ◽  
Anastazia T Banaszak ◽  
...  
Keyword(s):  
Voltage Dependence ◽  
Ph Regulation ◽  
Functional Characterization ◽  
Gene Encoding ◽  
Proton Channels ◽  
Gating Model ◽  
Mechanistic Insight ◽  
Voltage Dependent ◽  
Insight Into

Voltage-dependent proton-permeable channels are membrane proteins mediating a number of important physiological functions. Here we report the presence of a gene encoding for Hv1 voltage-dependent, proton-permeable channels in two species of reef-building corals. We performed a characterization of their biophysical properties and found that these channels are fast-activating and modulated by the pH gradient in a manner that makes them interesting models for studying these processes more easily. We have also developed an allosteric gating model that provides mechanistic insight into the modulation of voltage-dependence by protons. This work also represents the first functional characterization of any ion channel in scleractinian corals. We discuss the implications of the presence of these channels in the membranes of coral cells in the calcification and pH regulation processes and possible consequences of ocean acidification related to the function of these channels.

scholarly journals PE5–PPE4–EspG3 heterotrimer structure from mycobacterial ESX-3 secretion system gives insight into cognate substrate recognition by ESX systems

2020 ◽  
Vol 295 (36) ◽  
pp. 12706-12715
Author(s):  
Zachary A. Williamson ◽  
Catherine T. Chaton ◽  
William A. Ciocca ◽  
Natalia Korotkova ◽  
Konstantin V. Korotkov
Keyword(s):  
Cell Envelope ◽  
Substrate Recognition ◽  
Secretion System ◽  
Multiple Factors ◽  
Type Vii Secretion ◽  
Shape Complementarity ◽  
Numerous Type ◽  
Unique Shape ◽  
Insight Into

Mycobacterium tuberculosis has evolved numerous type VII secretion (ESX) systems to secrete multiple factors important for both growth and virulence across their cell envelope. ESX-1, ESX-3, and ESX-5 systems have been shown to each secrete a distinct set of substrates, including PE and PPE families of proteins, named for conserved Pro-Glu and Pro-Pro-Glu motifs in their N termini. Proper secretion of the PE–PPE proteins requires the presence of EspG, with each system encoding its own unique copy. There is no cross-talk between any of the ESX systems, and how each EspG recognizes its subset of PE–PPE proteins is currently unknown. The only current structural characterization of PE–PPE–EspG heterotrimers is from the ESX-5 system. Here we present the crystal structure of the PE5mt–PPE4mt–EspG3mm heterotrimer from the ESX-3 system. Our heterotrimer reveals that EspG3mm interacts exclusively with PPE4mt in a similar manner to EspG5, shielding the hydrophobic tip of PPE4mt from solvent. The C-terminal helical domain of EspG3mm is dynamic, alternating between “open” and “closed” forms, and this movement is likely functionally relevant in the unloading of PE–PPE heterodimers at the secretion machinery. In contrast to the previously solved ESX-5 heterotrimers, the PE–PPE heterodimer of our ESX-3 heterotrimer is interacting with its chaperone at a drastically different angle and presents different faces of the PPE protein to the chaperone. We conclude that the PPE–EspG interface from each ESX system has a unique shape complementarity that allows each EspG to discriminate among noncognate PE–PPE pairs.

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