Effect of Environmental Factors on the Catalytic Activity of Intramembrane Serine Protease

Siderophores are organic biomolecules synthesized by a wide variety of microbes. The molecules sequester ferric ion from environments where it is present at extremely low concentrations. Siderophores are of consequence with respect to microbial nutrition, pathogenicity, virulence, and microbe-plant interactions. How siderophores are degraded and returned to the carbon and nitrogen cycles is not well understood. The catalytic activity of an enzyme from a bacterium that degrades the siderophore deferrioxamine B has been examined. While the degradation of deferrioxamine B is sensitive to sulfhydryl and metal moiety inhibitors, the data presented is most consistent with the hypothesis that the enzyme uses a hydroxyl moiety (serine peptidase) to catalyze the degradation of deferrioxamine B. If sulfhydryl and metal inhibitors are simultaneously present at concentrations that when alone only partially inhibit the enzyme, the enzyme is unable to catalyze deferrioxamine B dissimilation. Analysis of the inhibitor experiments conducted led to the conclusion that the deferrioxamine B degrading enzyme is a serine-peptidase-like enzyme that needs calcium ions and sulfhydryl groups to be fully activated or stabilized. The knowledge of the catalytic moieties of the enzyme will be exploited to purify the enzyme.Key words: siderophores, deferrioxamine B, siderophore degradation.

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Lopap, a prothrombin activator from Lonomia obliqua belonging to the lipocalin family: recombinant production, biochemical characterization and structure–function insights

Biochemical Journal ◽

10.1042/bj20060325 ◽

2006 ◽

Vol 398 (2) ◽

pp. 295-302 ◽

Cited By ~ 22

Author(s):

Cleyson Valença Reis ◽

Sonia Aparecida Andrade ◽

Oscar Henrique Pereira Ramos ◽

Celso Raul Romero Ramos ◽

Paulo Lee Ho ◽

...

Keyword(s):

Catalytic Activity ◽

Serine Protease ◽

Calcium Binding ◽

Biochemical Characterization ◽

Structural Features ◽

Reading Frame ◽

Molecular Features ◽

Recombinant Production ◽

Lonomia Obliqua

Using a cDNA library made from Lonomia obliqua caterpillar bristles, we identified a transcript with a 603 bp open reading frame. The deduced protein corresponds to Lopap, a prothrombin activator previously isolated by our group from the bristles of this species. The mature protein is composed by 185 amino acids and shares similarity with members of the lipocalin family. The cDNA encoding the mature form was amplified by PCR, subcloned into pAE vector and used to transform Escherichia coli BL21(DE3) cells. As for the native Lopap, the recombinant fusion protein shows enzymatic activity, promotes prothrombin hydrolysis, generates fragments similar to prethrombin-2 and fragment 1.2 as intermediates, and generates thrombin as the final product. In addition, structural bioinformatics studies indicated several interesting molecular features, including the residues that could be responsible for Lopap's serine protease-like activity and the role of calcium binding in this context. Such catalytic activity has never been found in other members of the lipocalin family. This is the first report describing the recombinant production and biochemical characterization of a Lonomia obliqua lipocalin, as well as the structural features that could be responsible for its serine protease-like catalytic activity.

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Design, synthesis and catalytic activity of a serine protease synthetic model

Letters in Peptide Science ◽

10.1007/bf02442921 ◽

1997 ◽

Vol 4 (4-6) ◽

pp. 481-487 ◽

Cited By ~ 3

Author(s):

Athanassios Stavrakoudis ◽

Ioannis N. Demetropoulos ◽

Constantinos Sakarellos ◽

Maria Sakarellos-Daitsiotis ◽

Vassilios Tsikaris

Keyword(s):

Catalytic Activity ◽

Serine Protease ◽

Design Synthesis ◽

Synthetic Model

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Stacking interactions of W271 and H275 of SeMV serine protease with W43 of natively unfolded VPg confer catalytic activity to protease

Virology ◽

10.1016/j.virol.2008.08.034 ◽

2008 ◽

Vol 382 (1) ◽

pp. 83-90 ◽

Cited By ~ 12

Author(s):

Smita Nair ◽

P. Gayathri ◽

M.R.N. Murthy ◽

H.S. Savithri

Keyword(s):

Catalytic Activity ◽

Serine Protease ◽

Stacking Interactions ◽

Natively Unfolded

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Targeting the Complement Serine Protease MASP-2 as a Therapeutic Strategy for Coronavirus Infections

Viruses ◽

10.3390/v13020312 ◽

2021 ◽

Vol 13 (2) ◽

pp. 312

Author(s):

Ben M. Flude ◽

Giulio Nannetti ◽

Paige Mitchell ◽

Nina Compton ◽

Chloe Richards ◽

...

Keyword(s):

Catalytic Activity ◽

Lung Injury ◽

Serine Protease ◽

Complement Activation ◽

Lectin Pathway ◽

Vitro Assay ◽

Direct Inhibitors ◽

N Proteins ◽

Coronavirus Infections

MASP-2, mannose-binding protein-associated serine protease 2, is a key enzyme in the lectin pathway of complement activation. Hyperactivation of this protein by human coronaviruses SARS-CoV, MERS-CoV and SARS-CoV-2 has been found to contribute to aberrant complement activation in patients, leading to aggravated lung injury with potentially fatal consequences. This hyperactivation is triggered in the lungs through a conserved, direct interaction between MASP-2 and coronavirus nucleocapsid (N) proteins. Blocking this interaction with monoclonal antibodies and interfering directly with the catalytic activity of MASP-2, have been found to alleviate coronavirus-induced lung injury both in vitro and in vivo. In this study, a virtual library of 8736 licensed drugs and clinical agents has been screened in silico according to two parallel strategies. The first strategy aims at identifying direct inhibitors of MASP-2 catalytic activity, while the second strategy focusses on finding protein-protein interaction inhibitors (PPIs) of MASP-2 and coronaviral N proteins. Such agents could represent promising support treatment options to prevent lung injury and reduce mortality rates of infections caused by both present and future-emerging coronaviruses. Forty-six drug repurposing candidates were purchased and, for the ones selected as potential direct inhibitors of MASP-2, a preliminary in vitro assay was conducted to assess their interference with the lectin pathway of complement activation. Some of the tested agents displayed a dose-response inhibitory activity of the lectin pathway, potentially providing the basis for a viable support strategy to prevent the severe complications of coronavirus infections.

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Reductionist thinking and animal models in neuropsychiatric research

Behavioral and Brain Sciences ◽

10.1017/s0140525x18001231 ◽

2019 ◽

Vol 42 ◽

Cited By ~ 1

Author(s):

Nicole M. Baran

Keyword(s):

Animal Models ◽

Mental Disorders ◽

Environmental Factors ◽

Neuropsychiatric Disorders ◽

Model Organisms ◽

Developmental Genetic ◽

Term Study ◽

Genetic And Environmental Factors ◽

Mechanisms Of Plasticity

AbstractReductionist thinking in neuroscience is manifest in the widespread use of animal models of neuropsychiatric disorders. Broader investigations of diverse behaviors in non-model organisms and longer-term study of the mechanisms of plasticity will yield fundamental insights into the neurobiological, developmental, genetic, and environmental factors contributing to the “massively multifactorial system networks” which go awry in mental disorders.

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High resolution electron microscopy of lanthanum phosphate crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108519 ◽

1978 ◽

Vol 36 (1) ◽

pp. 274-275

Author(s):

J. C. Wheatley ◽

J. M. Cowley

Keyword(s):

Electron Microscopy ◽

Catalytic Activity ◽

High Resolution ◽

Petroleum Industry ◽

High Resolution Electron Microscopy ◽

Lanthanum Phosphate ◽

Good Catalyst ◽

Resolution Electron ◽

Good Catalytic Activity ◽

Physical And Chemical

Rare-earth phosphates are of particular interest because of their catalytic properties associated with the hydrolysis of many aromatic chlorides in the petroleum industry. Lanthanum phosphates (LaPO4) which have been doped with small amounts of copper have shown increased catalytic activity (1). However the physical and chemical characteristics of the samples leading to good catalytic activity are not known.Many catalysts are amorphous and thus do not easily lend themselves to methods of investigation which would include electron microscopy. However, the LaPO4, crystals are quite suitable samples for high resolution techniques.The samples used were obtained from William L. Kehl of Gulf Research and Development Company. The electron microscopy was carried out on a JEOL JEM-100B which had been modified for high resolution microscopy (2). Standard high resolution techniques were employed. Three different sample types were observed: 669A-1-5-7 (poor catalyst), H-L-2 (good catalyst) and 27-011 (good catalyst).

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