Identification and characterisation of the catalytic triad of the alkaliphilic thermotolerant PHA depolymerase PhaZ7 ofPaucimonas lemoignei

Photoisomerisation of a fumaramide/maleamide linker within a functionalised helical foldamer brings together a catalytic triad and activates catalytic esterase-like activity.

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A cysteine-histidine-aspartate catalytic triad is involved in glutamine amide transfer function in purF-type glutamine amidotransferases

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)84750-6 ◽

1989 ◽

Vol 264 (28) ◽

pp. 16613-16619

Author(s):

B Mei ◽

H Zalkin

Keyword(s):

Transfer Function ◽

Catalytic Triad

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Functional analysis of the catalytic triad of the hAT-family transposase TcBuster

Plasmid ◽

10.1016/j.plasmid.2021.102554 ◽

2021 ◽

Vol 114 ◽

pp. 102554

Author(s):

Lauren E. Woodard ◽

Felisha M. Williams ◽

Isria C. Jarrett ◽

Matthew H. Wilson

Keyword(s):

Functional Analysis ◽

Catalytic Triad

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Genome-Wide Expression Patterns of Rhoptry Kinases during the Eimeria tenella Life-Cycle

Microorganisms ◽

10.3390/microorganisms9081621 ◽

2021 ◽

Vol 9 (8) ◽

pp. 1621

Author(s):

Adeline Ribeiro E Silva ◽

Alix Sausset ◽

Françoise I. Bussière ◽

Fabrice Laurent ◽

Sonia Lacroix-Lamandé ◽

...

Keyword(s):

Life Cycle ◽

Expression Patterns ◽

Housekeeping Genes ◽

Catalytic Triad ◽

Eimeria Tenella ◽

Apicomplexan Parasites ◽

Genome Wide ◽

Infected Cells ◽

First And Second Generation

Kinome from apicomplexan parasites is composed of eukaryotic protein kinases and Apicomplexa specific kinases, such as rhoptry kinases (ROPK). Ropk is a gene family that is known to play important roles in host–pathogen interaction in Toxoplasma gondii but is still poorly described in Eimeria tenella, the parasite responsible for avian coccidiosis worldwide. In the E. tenella genome, 28 ropk genes are predicted and could be classified as active (n = 7), inactive (incomplete catalytic triad, n = 12), and non-canonical kinases (active kinase with a modified catalytic triad, n = 9). We characterized the ropk gene expression patterns by real-time quantitative RT-PCR, normalized by parasite housekeeping genes, during the E. tenella life-cycle. Analyzed stages were: non-sporulated oocysts, sporulated oocysts, extracellular and intracellular sporozoites, immature and mature schizonts I, first- and second-generation merozoites, and gametes. Transcription of all those predicted ropk was confirmed. The mean intensity of transcription was higher in extracellular stages and 7–9 ropk were specifically transcribed in merozoites in comparison with sporozoites. Transcriptional profiles of intracellular stages were closely related to each other, suggesting a probable common role of ROPKs in hijacking signaling pathways and immune responses in infected cells. These results provide a solid basis for future functional analysis of ROPK from E. tenella.

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Effects of viscosity and osmotic stress on the reaction of human butyrylcholinesterase with cresyl saligenin phosphate, a toxicant related to aerotoxic syndrome: kinetic and molecular dynamics studies

Biochemical Journal ◽

10.1042/bj20130389 ◽

2013 ◽

Vol 454 (3) ◽

pp. 387-399 ◽

Cited By ~ 34

Author(s):

Patrick Masson ◽

Sofya Lushchekina ◽

Lawrence M. Schopfer ◽

Oksana Lockridge

Keyword(s):

Osmotic Stress ◽

Osmotic Pressure ◽

Active Site ◽

Md Simulations ◽

Catalytic Triad ◽

Wild Type ◽

Irreversible Inhibitor ◽

Enzyme Active Site ◽

Diffusion Controlled ◽

Peripheral Site

CSP (cresyl saligenin phosphate) is an irreversible inhibitor of human BChE (butyrylcholinesterase) that has been involved in the aerotoxic syndrome. Inhibition under pseudo-first-order conditions is biphasic, reflecting a slow equilibrium between two enzyme states E and E′. The elementary constants for CSP inhibition of wild-type BChE and D70G mutant were determined by studying the dependence of inhibition kinetics on viscosity and osmotic pressure. Glycerol and sucrose were used as viscosogens. Phosphorylation by CSP is sensitive to viscosity and is thus strongly diffusion-controlled (kon≈108 M−1·min−1). Bimolecular rate constants (ki) are about equal to kon values, making CSP one of the fastest inhibitors of BChE. Sucrose caused osmotic stress because it is excluded from the active-site gorge. This depleted the active-site gorge of water. Osmotic activation volumes, determined from the dependence of ki on osmotic pressure, showed that water in the gorge of the D70G mutant is more easily depleted than that in wild-type BChE. This demonstrates the importance of the peripheral site residue Asp70 in controlling the active-site gorge hydration. MD simulations provided new evidence for differences in the motion of water within the gorge of wild-type and D70G enzymes. The effect of viscosogens/osmolytes provided information on the slow equilibrium E⇌E′, indicating that alteration in hydration of a key catalytic residue shifts the equilibrium towards E′. MD simulations showed that glycerol molecules that substitute for water molecules in the enzyme active-site gorge induce a conformational change in the catalytic triad residue His438, leading to the less reactive form E′.

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