Structure and characterization of amidase from Rhodococcus sp. N-771: Insight into the molecular mechanism of substrate recognition

2010 ◽  
Vol 1804 (1) ◽  
pp. 184-192 ◽  
Author(s):  
Akashi Ohtaki ◽  
Kensuke Murata ◽  
Yuichi Sato ◽  
Keiichi Noguchi ◽  
Hideyuki Miyatake ◽  
...  
Keyword(s):  
Molecular Mechanism ◽  
Substrate Recognition ◽  
Insight Into ◽  
Rhodococcus Sp

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 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.

scholarly journals Structural studies on dehydroshikimate dehydratase

2014 ◽  
Vol 70 (a1) ◽  
pp. C475-C475
Author(s):  
James Peek ◽  
Dinesh Christendat
Keyword(s):  
Sole Carbon Source ◽  
Catalytic Mechanism ◽  
Substrate Recognition ◽  
Structural Studies ◽  
Sugar Phosphate ◽  
X Ray ◽  
Structural Insight ◽  
Functional Relevance ◽  
Insight Into

The soil bacterium, Pseudomonas putida, is capable of using the alicyclic compound quinate as a sole carbon source. During this process, quinate is converted to 3-dehydroshikimate, which subsequently undergoes a dehydration to form protocatechuate. The latter transformation is performed by the enzyme dehydroshikimate dehydratase (DSD). We have recombinantly produced DSD from P. putida and are currently performing x-ray crystallographic studies on the enzyme to gain structural insight into its catalytic mechanism and mode of substrate recognition. Initial crystals of DSD diffracted to 2.7 Ä resolution, but exhibited strong twinning. A redesigned construct has recently yielded crystals that diffract to similar resolution, but with a significantly reduced tendency toward twinning. Interestingly, sequence analysis of P. putida DSD reveals that the protein is in fact a fusion of two distinct domains: an N-terminal sugar phosphate isomerase-like domain associated with DSD activity, and a C-terminal hydroxyphenylpyruvate dioxygenase (HPPD)-like domain with unknown functional significance. Structural characterization of the protein may provide novel insight into the functional relevance of the unusual HPPD-like domain.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

scholarly journals First Insight into Nutraceutical Properties of Local Salento Cichorium intybus Varieties: NMR-Based Metabolomic Approach

2021 ◽  
Vol 18 (8) ◽  
pp. 4057
Author(s):  
Chiara Roberta Girelli ◽  
Francesca Serio ◽  
Rita Accogli ◽  
Federica Angilè ◽  
Antonella De Donno ◽  
...  
Keyword(s):  
1H Nmr ◽  
Cichorium Intybus ◽  
Resonance Spectroscopy ◽  
Metabolic Profiles ◽  
Whole Plant ◽  
Different Content ◽  
Insight Into ◽  
Nutraceutical Properties ◽  
Metabolomic Approach

Background: Plants of genus Cichorium are known for their therapeutic and nutraceutical properties determined by a wealth of phytochemical substances contained in the whole plant. The aim of this paper was to characterize the metabolic profiles of local Salento chicory (Cichorium intybus L.) varieties (“Bianca”, “Galatina”, “Leccese”, and “Otranto”) in order to describe their metabolites composition together with possible bioactivity and health beneficial properties. Methods: The investigation was performed by 1H-NMR spectroscopy and Multivariate Analysis (MVA), by which the metabolic profiles of the samples were easily obtained and compared. Results: The supervised Partial Least Squares Discriminant Analysis (PLS-DA) analysis showed as “Bianca” and “Galatina” samples grouped together separated by “Leccese” and “Otranto” varieties. A different content of free amino acids and organic acids was observed among the varieties. In particular a high content of cichoric and monocaffeoyl tartaric acid was observed for the “Leccese” variety. The presence of secondary metabolites adds significant interest in the investigation of Cichorium inthybus, as this vegetable may benefit human health when incorporated into the diet. Conclusions: The 1H-NMR (Nuclear Magnetic Resonance Spectroscopy) based characterization of Salento chicory varieties allowed us to determine the potential usefulness and nutraceutical properties of the product, also providing a method to guarantee its authenticity on a molecular scale.

“Real-World” Microscopy: Understanding Environment-Sensitive Behavior of Ni-Base Welds

1998 ◽  
Vol 4 (S2) ◽  
pp. 528-529
Author(s):  
M. G. Burke ◽  
R. J. Wehrer ◽  
C.M. Brown
Keyword(s):  
Nuclear Power ◽  
Base Alloy ◽  
Analytical Electron Microscopy ◽  
Furnace Cool ◽  
Environmental Embrittlement ◽  
Reported Study ◽  
Compositional Changes ◽  
Insight Into ◽  
Sensitive Behavior

Ni-base alloy welds such as EN82H weld metal are frequently employed in nuclear power applications where resistance to corrosion is required. Results of a recently reported study of the mechanical properties of EN82H welds show that this alloy is susceptible to low-temperature (∼100°C) environmental embrittlement (LTEE) in hydrogenated water. LTEE is a manifestation of hydrogen embrittlement in these alloys.1 Recent LTEE tests have demonstrated a beneficial effect of a high-temperature (∼1100°C) anneal and furnace-cool in alleviating the material's susceptibility to LTEE. Understanding the reason for the reduction in LTEE susceptibility requires detailed characterization of the microstructure so that the specific structural and compositional changes that have been induced by the solution-anneal can be identified. This study reports the results of light optical and analytical electron microscopy (AEM) characterization of the microstructures of as-fabricated and as-solution-annealed EN82H welds with the objective of providing insight into the observed LTEE behavior.

Sign in / Sign up

Export Citation Format

Share Document