Search results for "RICH"
showing 10 items of 3360 documents
Active surfaces engineered by immobilizing protein-polymer nanoreactors for selectively detecting sugar alcohols.
2016
We introduce active surfaces generated by immobilizing protein-polymer nanoreactors on a solid support for sensitive sugar alcohols detection. First, such selective nanoreactors were engineered in solution by simultaneous encapsulation of specific enzymes in copolymer polymersomes, and insertion of membrane proteins for selective conduct of sugar alcohols. Despite the artificial surroundings, and the thickness of the copolymer membrane, functionality of reconstituted Escherichia coli glycerol facilitator (GlpF) was preserved, and allowed selective diffusion of sugar alcohols to the inner cavity of the polymersome, where encapsulated ribitol dehydrogenase (RDH) enzymes served as biosensing e…
Solution NMR structure of Borrelia burgdorferi outer surface lipoprotein BBP28, a member of the mlp protein family.
2020
Lyme disease is the most widespread vector‐transmitted disease in North America and Europe, caused by infection with Borrelia burgdorferi sensu lato complex spirochetes. We report the solution NMR structure of the B. burgdorferi outer surface lipoprotein BBP28, a member of the multicopy lipoprotein (mlp) family. The structure comprises a tether peptide, five α‐helices and an extended C‐terminal loop. The fold is similar to that of Borrelia tunicate outer surface protein BTA121, which is known to bind lipids. These results contribute to the understanding of Lyme disease pathogenesis by revealing the molecular structure of a protein from the widely found mlp family. This article is protected …
The Parkinson Disease Gene LRRK2: Evolutionary and Structural Insights
2006
Mutations in the human leucine-rich repeat kinase 2 (LRRK2) gene are associated with both familial and sporadic Parkinson disease (PD). LRRK2 belongs to a gene family known as Roco. Roco genes encode for large proteins with several protein domains. Particularly, all Roco proteins have a characteristic GTPase domain, named Roc, plus a domain of unknown function called COR. In addition, LRRK2 and several other Roco proteins also contain a protein kinase domain. In this study, I use a combination of phylogenetic and structural analyses of the COR, Roc, and kinase domains present in Roco proteins to describe the origin and evolutionary history of LRRK2. Phylogenetic analyses using these domains…
Activation of Anthranilate Phosphoribosyltransferase from Sulfolobus solfataricus by Removal of Magnesium Inhibition and Acceleration of Product Rele…
2009
Anthranilate phosphoribosyltransferase from the hyperthermophilic archaeon Sulfolobus solfataricus (ssAnPRT) is encoded by the sstrpD gene and catalyzes the reaction of anthranilate (AA) with a complex of Mg(2+) and 5'-phosphoribosyl-alpha1-pyrophosphate (Mg.PRPP) to N-(5'-phosphoribosyl)-anthranilate (PRA) and pyrophosphate (PP(i)) within tryptophan biosynthesis. The ssAnPRT enzyme is highly thermostable (half-life at 85 degrees C = 35 min) but only marginally active at ambient temperatures (turnover number at 37 degrees C = 0.33 s(-1)). To understand the reason for the poor catalytic proficiency of ssAnPRT, we have isolated from an sstrpD library the activated ssAnPRT-D83G + F149S double …
The NMR structure of the sensory domain of the membranous two-component fumarate sensor (histidine protein kinase) DcuS of Escherichia coli
2003
The structure of the water-soluble, periplasmic domain of the fumarate sensor DcuS (DcuS-pd) has been determined by NMR spectroscopy in solution. DcuS is a prototype for a sensory histidine kinase with transmembrane signal transfer. DcuS belongs to the CitA family of sensors that are specific for sensing di- and tricarboxylates. The periplasmic domain is folded autonomously and shows helices at the N and the C terminus, suggesting direct linking or connection to helices in the two transmembrane regions. The structure constitutes a novel fold. The nearest structural neighbor is the Per-Arnt-Sim domain of the photoactive yellow protein that binds small molecules covalently. Residues Arg107, H…
Mutational analysis of disulfide bonds in the trypsin-reactive subdomain of a Bowman-Birk-type inhibitor of trypsin and chymotrypsin--cooperative ver…
1998
It is widely believed that protein folding is a hierarchical process proceeding from secondary structure via subdomains and domains towards the complete tertiary structure. Accordingly, protein subdomains should behave as independent folding units. However, this prediction would underestimate the well-established structural significance of tertiary context and domain interfaces in proteins. The principal objective of this work was to distinguish between autonomous and cooperative refolding of protein subdomains by means of mutational analysis. The double-headed Bowman-Birk inhibitor of trypsin and chymotrypsin of known crystal structure was selected for study. The relative orientation of th…
Folding and stability of the aquaglyceroporin GlpF: Implications for human aqua(glycero)porin diseases
2015
AbstractAquaporins are highly selective polytopic transmembrane channel proteins that facilitate the permeation of water across cellular membranes in a large diversity of organisms. Defects in aquaporin function are associated with common diseases, such as nephrogenic diabetes insipidus, congenital cataract and certain types of cancer. In general, aquaporins have a highly conserved structure; from prokaryotes to humans. The conserved structure, together with structural dynamics and the structural framework for substrate selectivity is discussed. The folding pathway of aquaporins has been a topic of several studies in recent years. These studies revealed that a conserved protein structure ca…
Characterization of the pleiotropic LysR-type transcription regulator LeuO of Escherichia coli
2019
AbstractLeuO is a pleiotropic LysR-type transcriptional regulator (LTTR) and co-regulator of the abundant nucleoid-associated repressor protein H-NS in Gammaproteobacteria. As other LTTRs, LeuO is a tetramer that is formed by dimerization of the N-terminal DNA-binding domain (DBD) and C-terminal effector-binding domain (EBD). To characterize the Escherichia coli LeuO protein, we screened for LeuO mutants that activate the cas (CRISPR-associated/Cascade) promoter more effectively than wild-type LeuO. This yielded nine mutants carrying amino acid substitutions in the dimerization interface of the regulatory EBD, as shown by solving the EBD’s crystal structure. Superimposing of the crystal str…
Protein isotope effects in dihydrofolate reductase from Geobacillus stearothermophilus show entropic-enthalpic compensatory effects on the rate const…
2014
Catalysis by dihydrofolate reductase from the moderately thermophilic bacterium Geobacillus stearothermophilus (BsDHFR) was investigated by isotope substitution of the enzyme. The enzyme kinetic isotope effect for hydride transfer was close to unity at physiological temperatures but increased with decreasing temperatures to a value of 1.65 at 5 °C. This behavior is opposite to that observed for DHFR from Escherichia coli (EcDHFR), where the enzyme kinetic isotope effect increased slightly with increasing temperature. These experimental results were reproduced in the framework of variational transition-state theory that includes a dynamical recrossing coefficient that varies with the mass of…
Promiscuity in alkaline phosphatase superfamily. Unraveling evolution through molecular simulations.
2011
We here present a theoretical study of the alkaline hydrolysis of a phosphodiester (methyl p-nitrophenyl phosphate or MpNPP) in the active site of Escherichia coli alkaline phosphatase (AP), a monoesterase that also presents promiscuous activity as a diesterase. The analysis of our simulations, carried out by means of molecular dynamics (MD) simulations with hybrid quantum mechanics/molecular mechanics (QM/MM) potentials, shows that the reaction takes place through a D(N)A(N) or dissociative mechanism, the same mechanism employed by AP in the hydrolysis of monoesters. The promiscuous activity observed in this superfamily can be then explained on the basis of a conserved reaction mechanism. …