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Biomedical subjects

Bernadette Byrne

Publications and source records attributed to Bernadette Byrne.

6 recordsLinked to original sources
PubMed2003

Using rational screening and electron microscopy to optimize the crystallization of succinate:ubiquinone oxidoreductase from Escherichia coli.

The membrane-bound respiratory complex II, succinate:ubiquinone oxidoreductase (SQR) from Escherichia coli, has been anaerobically expressed, then purified and crystallized. The initial crystals obtained were small and diffracted poorly. In order to facilitate structure determination, rational screening and sample-quality analysis using electron microscopy was implemented. The crystals of SQR from E. coli belong to the trigonal space group R32, with unit-cell parameters a = b = 138.7, c = 521.9 A, and diffract to 2.6 A resolution. The optimization strategy used for obtaining well diffracting SQR crystals is applicable to a wide range of membrane proteins.

Anisotropy↗
PubMed2003

Architecture of succinate dehydrogenase and reactive oxygen species generation.

The structure of Escherichia coli succinate dehydrogenase (SQR), analogous to the mitochondrial respiratory complex II, has been determined, revealing the electron transport pathway from the electron donor, succinate, to the terminal electron acceptor, ubiquinone. It was found that the SQR redox centers are arranged in a manner that aids the prevention of reactive oxygen species (ROS) formation at the flavin adenine dinucleotide. This is likely to be the main reason SQR is expressed during aerobic respiration rather than the related enzyme fumarate reductase, which produces high levels of ROS. Furthermore, symptoms of genetic disorders associated with mitochondrial SQR mutations may be a result of ROS formation resulting from impaired electron transport in the enzyme.

Aerobiosis↗
PubMed2002

Molecular basis of proton motive force generation: structure of formate dehydrogenase-N.

The structure of the membrane protein formate dehydrogenase-N (Fdn-N), a major component of Escherichia coli nitrate respiration, has been determined at 1.6 angstroms. The structure demonstrates 11 redox centers, including molybdopterin-guanine dinucleotides, five [4Fe-4S] clusters, two heme b groups, and a menaquinone analog. These redox centers are aligned in a single chain, which extends almost 90 angstroms through the enzyme. The menaquinone reduction site associated with a possible proton pathway was also characterized. This structure provides critical insights into the proton motive force generation by redox loop, a common mechanism among a wide range of respiratory enzymes.

Binding Sites↗
PubMed2002

Membrane protein complexes.

A wide range of membrane protein structures have been published during the past two years. These have included proteins from both eucaryotic and heterologously overexpressed sources. Whereas some of these proteins were crystallised using conventional techniques, others employed the new methods of lipidic cubic phase crystallisation and antibody fragment co-crystallisation. These and other new approaches to the expression and crystallisation of membrane proteins are accelerating structural studies of membrane protein complexes.

Bacterial Outer Membrane Proteins↗
PubMed2001

Purification and crystallization of the respiratory complex formate dehydrogenase-N from Escherichia coli.

A membrane-protein complex, formate dehydrogenase-N from Escherichia coli, has been purified and crystallized. This molybdenum-containing enzyme, composed of alpha, beta and gamma subunits, is the major electron donor to the nitrate respiratory chain of E. coli. The formate dehydrogenase-N crystals belong to the cubic space group P2(1)3, with unit-cell parameters a = b = c = 203 A. An asymmetric unit of the crystals is assumed to contain one formate dehydrogenase-N monomer (MW 170 kDa). One data set to 1.6 A resolution, with 342 711 independent observations (94.4% complete) and an R(merge) of 0.08, has been collected from a single crystal. This is the highest resolution data set reported for a membrane-protein complex to date.

Crystallization↗