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Biomedical subjects

M G Rossmann

Publications and source records attributed to M G Rossmann.

At least 37 records · Page 2Linked to original sources
PubMed1999

Analysis of three structurally related antiviral compounds in complex with human rhinovirus 16.

Rhinoviruses are a frequent cause of the common cold. A series of antirhinoviral compounds have been developed that bind into a hydrophobic pocket in the viral capsid, stabilizing the capsid and interfering with cell attachment. The structures of a variety of such compounds, complexed with rhinovirus serotypes 14, 16, 1A, and 3, previously have been examined. Three chemically similar compounds, closely related to a drug that is undergoing phase III clinical trials, were chosen to determine the structural impact of the heteroatoms in one of the three rings. The compounds were found to have binding modes that depend on their electronic distribution. In the compound with the lowest efficacy, the terminal ring is displaced by 1 A and rotated by 180 degrees relative to the structure of the other two. The greater polarity of the terminal ring in one of the three compounds leads to a small displacement of its position relative to the other compounds in the hydrophobic end of the antiviral compound binding pocket to a site where it makes fewer interactions. Its lower efficacy is likely to be the result of the reduced number of interactions. A region of conserved residues has been identified near the entrance to the binding pocket where there is a corresponding conservation of the mode of binding of these compounds to different serotypes. Thus, variations in residues lining the more hydrophobic end of the pocket are primarily responsible for the differences in drug efficacies.

Antiviral Agents↗
PubMed1999

Review: rhinoviruses and their ICAM receptors.

The normal function of human intercellular adhesion molecule-1 (ICAM-1) is to provide adhesion between endothelial cells and leukocytes after injury or stress. ICAM-1 binds to leukocyte function-associated antigen or macrophage-1 antigen. However, ICAM-1 is also used as a receptor by the major group of human rhinoviruses and is a catalyst for the subsequent viral uncoating during cell entry. The three-dimensional atomic structure of the two amino-terminal domains (D1 and D2) of ICAM-1 has been determined to 2.2 A resolution and fitted into a cryoelectron microscopy reconstruction of a rhinovirus-ICAM-1 complex. Rhinovirus attachment is confined to the BC, CD, DE, and FG loops of the amino-terminal Ig-like domain (D1) at the end distal to the cellular membrane. The loops are considerably different in structure to those of human ICAM-2 or murine ICAM-1, which do not bind rhinoviruses. There are extensive charge interactions between ICAM-1 and human rhinoviruses, which are mostly conserved in both major and minor receptor groups of rhinoviruses.

Animals↗
PubMed1999

Structural studies of two rhinovirus serotypes complexed with fragments of their cellular receptor.

Two human rhinovirus serotypes complexed with two- and five-domain soluble fragments of the cellular receptor, intercellular adhesion molecule-1, have been investigated by X-ray crystallographic analyses of the individual components and by cryo-electron microscopy of the complexes. The three-dimensional image reconstructions provide a molecular envelope within which the crystal structures of the viruses and the receptor fragments can be positioned with accuracy. The N-terminal domain of the receptor binds to the rhinovirus 'canyon' surrounding the icosahedral 5-fold axes. Fitting of molecular models into the image reconstruction density identified the residues on the virus that interact with those on the receptor surface, demonstrating complementarity of the electrostatic patterns for the tip of the N-terminal receptor domain and the floor of the canyon. The complexes seen in the image reconstructions probably represent the first stage of a multistep binding process. A mechanism is proposed for the subsequent viral uncoating process.

Binding Sites↗
PubMed1999

The structure of bacteriophage T4 gene product 9: the trigger for tail contraction.

BACKGROUND: The T4 bacteriophage consists of a head, filled with double-stranded DNA, and a complex contractile tail required for the ejection of the viral genome into the Escherichia coli host. The tail has a baseplate to whïch are attached six long and six short tail fibers. These fibers are the sensing devices for recognizing the host. When activated by attachment to cell receptors, the fibers cause a conformational transition in the baseplate and subsequently in the tail sheath, which initiates DNA ejection. The baseplate is a multisubunit complex of proteins encoded by 15 genes. Gene product 9 (gp9) is the protein that connects the long tail fibers to the baseplate and triggers the tail contraction after virus attachment to a host cell. RESULTS: The crystal structure of recombinant gp9, determined to 2.3 A resolution, shows that the protein of 288 amino acid residues assembles as a homotrimer. The monomer consists of three domains: the N-terminal domain generates a triple coiled coil; the middle domain is a mixed, seven-stranded beta sandwich with a topology not previously observed; and the C-terminal domain is an eight-stranded, antiparallel beta sandwich having some resemblance to 'jelly-roll' viral capsid protein structures. CONCLUSIONS: The biologically active form of gp9 is a trimer. The protein contains flexible interdomain hinges, which are presumably required to facilitate signal transmission between the long tail fibers and the baseplate. Structural and genetic analyses show that the C-terminal domain is bound to the baseplate, and the N-terminal coiled-coil domain is associated with the long tail fibers.

Amino Acid Sequence↗
PubMed1999

X-ray crystallographic structure of the Norwalk virus capsid.

Norwalk virus, a noncultivatable human calicivirus, is the major cause of epidemic gastroenteritis in humans. The first x-ray structure of a calicivirus capsid, which consists of 180 copies of a single protein, has been determined by phase extension from a low-resolution electron microscopy structure. The capsid protein has a protruding (P) domain connected by a flexible hinge to a shell (S) domain that has a classical eight-stranded beta-sandwich motif. The structure of the P domain is unlike that of any other viral protein with a subdomain exhibiting a fold similar to that of the second domain in the eukaryotic translation elongation factor-Tu. This subdomain, located at the exterior of the capsid, has the largest sequence variation among Norwalk-like human caliciviruses and is likely to contain the determinants of strain specificity and cell binding.

Amino Acid Sequence↗
PubMed1999

The role of scaffolding proteins in the assembly of the small, single-stranded DNA virus phiX174.

An empty precursor particle called the procapsid is formed during assembly of the single-stranded DNA bacteriophage phiX174. Assembly of the phiX174 procapsid requires the presence of the two scaffolding proteins, D and B, which are structural components of the procapsid, but are not found in the mature virion. The X-ray crystallographic structure of a "closed" procapsid particle has been determined to 3.5 A resolution. This structure has an external scaffold made from 240 copies of protein D, 60 copies of the internally located B protein, and contains 60 copies of each of the viral structural proteins F and G, which comprise the shell and the 5-fold spikes, respectively. The F capsid protein has a similar conformation to that seen in the mature virion, and differs from the previously determined 25 A resolution electron microscopic reconstruction of the "open" procapsid, in which the F protein has a different conformation. The D scaffolding protein has a predominantly alpha-helical fold and displays remarkable conformational variability. We report here an improved and refined structure of the closed procapsid and describe in some detail the differences between the four independent D scaffolding proteins per icosahedral asymmetric unit, as well as their interaction with the F capsid protein. We re-analyze and correct the comparison of the closed procapsid with the previously determined cryo-electron microscopic image reconstruction of the open procapsid and discuss the major structural rearrangements that must occur during assembly. A model is proposed in which the D proteins direct the assembly process by sequential binding and conformational switching.

Amino Acid Sequence↗
PubMed1999

The structure of the two amino-terminal domains of human intercellular adhesion molecule-1 suggests how it functions as a rhinovirus receptor.

The normal function of human intercellular adhesion molecule-1 (ICAM-1) is to provide adhesion between endothelial cells and leukocytes after injury or stress. ICAM-1 binds to leukocyte function-associated antigen (LFA-1) or macrophage-1 antigen (Mac-1). However, ICAM-1 is also utilized as a receptor by the major group of human rhinoviruses and is a catalyst for the subsequent viral uncoating during cell entry. The three-dimensional atomic structure of the two amino-terminal domains (D1 and D2) of ICAM-1 has been determined to 2.2 A resolution and fitted into a cryo-electron microscopy reconstruction of a rhinovirus-ICAM-1 complex. Rhinovirus attachment is confined to the BC, CD, DE and FG loops of the amino-terminal immunoglobulin-like domain (D1) at the end distal to the cellular membrane. The loops are considerably different in structure to those of human ICAM-2 or murine ICAM-1 which do not bind rhinoviruses. There are extensive charge interactions between ICAM-1 and human rhinoviruses, which are mostly conserved in both major and minor receptor groups of rhinoviruses. The interaction of ICAMs with LFA-1 is known to be mediated by a divalent cation bound to the I-(insertion) domain on the alpha chain of LFA-1 and the carboxy group of a conserved glutamic acid residue on ICAMs. Domain D1 has been docked with the known structure of the I-domain. The resultant model is consistent with mutational data and provides a structural framework for the adhesion between these molecules.

Amino Acid Sequence↗
PubMed1999

Structural insight into insect viruses.

The first structure of an insect picorna-(small RNA-containing) virus is now available. Although there is considerable similarity in the structures of mammalian and insect picornaviruses, there are also remarkable differences, the most noteworthy being associated with the small, internal, functionally essential, VP4 protein.

Insect Viruses↗
PubMed1999

Data processing.

X-ray diffraction data processing proceeds through indexing, pre-refinement of camera parameters and crystal orientation, intensity integration, post-refinement and scaling. The DENZO program has set new standards for autoindexing, but no publication has appeared which describes the algorithm. In the development of the new Data Processing Suite (DPS), one of the first aims has been the development of an autoindexing procedure at least as powerful as that used by DENZO. The resultant algorithm will be described. Another major problem which has arisen in recent years is scaling and post-refinement of data from different images when there are few, if any, full reflections. This occurs when the mosaic spread approaches or exceeds the angle of oscillation, as is usually the case for frozen crystals. A procedure which is able to obtain satisfactory results for such a situation will be described.

Algorithms↗
PubMed1998

The structure of an insect parvovirus (Galleria mellonella densovirus) at 3.7 A resolution.

BACKGROUND: Parvoviruses infect vertebrates, insects and crustaceans. Many arthropod parvoviruses (densoviruses) are highly pathogenic and kill approximately 90% of the host larvae within days, making them potentially effective as selective pesticides. Improved understanding of densoviral structure and function is therefore desirable. There are four different initiation sites for translation of the densovirus capsid protein mRNA, giving rise to the viral proteins VP1 to VP4. Sixty copies of the common, C-terminal domain make up the ordered part of the icosahedral capsid. RESULTS: The Galleria mellonella densovirus (GMDNV) capsid protein consists of a core beta-barrel motif, similar to that found in many other viral capsid proteins. The structure most closely resembles that of the vertebrate parvoviruses, but it has diverged beyond recognition in many of the long loop regions that constitute the surface features and intersubunit contacts. The N termini of twofold-related subunits have swapped their positions relative to those of the vertebrate parvoviruses. Unlike in the vertebrate parvoviruses, in GmDNV there is no continuous electron density in the channels running along the fivefold axes of the virus. Electron density corresponding to some of the single-stranded DNA genome is visible in the crystal structure, but it is not as well defined as in the vertebrate parvoviruses. CONCLUSIONS: The sequence of the glycine-rich motif, which occupies each of the channels along the fivefold axes in vertebrate viruses, is conserved between mammalian and insect parvoviruses. This motif may serve to externalize the N-terminal region of the single VP1 subunit per particle. The domain swapping of the N termini between insect and vertebrate parvoviruses may have the effect of increasing capsid stability in GmDNV.

Amino Acid Sequence↗
PubMed1998

Functional implications of the structure of the murine parvovirus, minute virus of mice.

BACKGROUND: Minute virus of mice (MVM) is a single-stranded (ss) DNA-containing, murine parvovirus with a capsid built up of 60 icosahedrally related polypeptide chains, each of which consists of the C-terminal region common to two structural proteins, VP1 and VP2. In infectious virions, most VP2 molecules are cleaved to VP3 by the removal of about 20 amino acids from the N terminus. Of the 587 amino acids in VP2, approximately half are identical to those in the analogous capsid protein of the antigenically distinct canine parvovirus (CPV), the crystal structure of which has previously been determined. The three-dimensional structure determination of MVMi (the immunosuppressive strain of MVM) was previously reported to 3.5 A resolution. RESULTS: We report here an analysis of the MVMi virus structure and provide insights into tissue tropism, antigenicity and DNA packaging. Amino acids determining MVM tissue tropism were found to cluster on, or near, the viral surface. A conserved, glycine-rich, N-terminal peptide was seen to run through a cylindrical channel along each fivefold axis and may have implications for antigenicity. Density within the virion was interpreted as 29 ssDNA nucleotides per icosahedral asymmetric unit, and accounts for over one-third of the viral genome. CONCLUSIONS: The presence of the glycine-rich sequence in the fivefold channels of MVMi provides a possible mechanism to explain how the unique N-terminal region of VP1 becomes externalized in infectious parvovirions. Residues that determine tropism may form an attachment recognition site for a secondary host-cell factor that modulates tissue specificity. The ordering of nucleotides in a similar region of the interior surface in the CPV and MVMi capsids suggests the existence of a genomic DNA-recognition site within the parvoviral capsid.

Amino Acid Sequence↗
PubMed1998

Probing the potential glycoprotein binding site of sindbis virus capsid protein with dioxane and model building.

Alphavirus budding from the plasma membrane is initiated by the specific interaction of the nucleocapsid with the cytoplasmic domain of the glycoprotein E2. It was proposed (Lee et al., Structure 4:531-541, 1996) that binding of the capsid protein residues 108 to 110 (the "N-terminal arm" residues) to a hydrophobic pocket on the surface of the neighboring capsid protein in the crystal structure mimics the binding of the E2 C-terminal residues into this pocket. In addition, structural comparisons of wild-type and mutant Sindbis virus capsid protein (SCP) and Semliki Forest virus capsid protein suggested that budding is associated with a switch between two conformations of the hydrophobic pocket. To test the proposed mechanism, SCP(114-264), which is missing the N-terminal arm, was crystallized to examine the pocket conformation when the pocket is empty. However, the pocket was occupied by dioxane molecules from the crystallization solution. The pocket conformation was the same as that when it was occupied by the N-terminal arm, demonstrating that the pocket favors binding ligands of appropriate size and shape.

Amino Acid Sequence↗
PubMed1998

Assembly of a tailed bacterial virus and its genome release studied in three dimensions.

We present the first three-dimensional reconstruction of a prolate, tailed phage, and its empty prohead precursor by cryo-electron microscopy. The head-tail connector, the central component of the DNA packaging machine, is visualized for the first time in situ within the Bacillus subtilis dsDNA phage phi29. The connector, with 12- or 13-fold symmetry, appears to fit loosely into a pentameric vertex of the head, a symmetry mismatch that may be required to rotate the connector to package DNA. The prolate head of phi29 has 10 hexameric units in its cylindrical equatorial region, and 11 pentameric and 20 hexameric units comprise icosahedral end-caps with T=3 quasi-symmetry. Reconstruction of an emptied phage particle shows that the connector and neck/tail assembly undergo significant conformational changes upon ejection of DNA.

Bacillus Phages↗
PubMed1998

Structure of bacteriophage T4 fibritin M: a troublesome packing arrangement.

Fibritin, a 52 kDa product of bacteriophage T4 gene wac, forms 530 A long fibers, named whiskers, that attach to the phage neck and perform a helper function during phage assembly. Fibritin is a homotrimer, with its predominant central domain consisting of 12 consecutive alpha-helical coiled-coil segments linked together by loops. The central domain is flanked by small globular domains at both ends. Fibritin M is a genetically engineered fragment of the wild type and contains 74 amino-acid residues corresponding to the last coiled-coil segment and the complete carboxy-terminal domain. The crystals of fibritin M belong to the rare space group P3 with three crystallographically independent trimers in the unit cell. The structure has been established at 1.85 A resolution by combining molecular and isomorphous replacement techniques. One of the two heavy-atom derivatives used was gaseous xenon. A substantial fraction of residues in each independent trimer is disordered to various extents in proportion to the lack of restraints on the molecules provided by the lattice contacts. Accurate modeling of the solvent present in the crystals was crucial for achieving good agreement with experimental data.

Amino Acid Sequence↗
PubMed1998

Structure determination of the phiX174 closed procapsid.

The structure of a procapsid of the single-stranded DNA bacteriophage ++phiX174 was determined to 3.5 A resolution. The crystal space group was I213 with a unit-cell length of 774 A. The unit cell contained 16 icosahedral virus particles, each situated on a crystallographic threefold axis. Thus, there are two independent one-thirds of a particle per asymmetric unit, and a total of 40-fold non-crystallographic redundancy. To aid in the interpretation of the packing arrangement, crystals were prepared for thin sectioning and analyzed by electron microscopy. Oscillation X-ray diffraction data was collected on image plates using synchrotron radiation and oscillation angles of either 0.25 or 0.30 degrees. A low-resolution 6.5 A data set collected from a single frozen crystal was particularly helpful in the structure determination, because of its completeness and internal consistency. The initial particle orientations were determined using self-rotation functions, while the initial position of one particle was determined from a Patterson map. The structure was solved by molecular replacement real-space averaging using a model based on a cryo-electron microscopy reconstruction as a starting point for the phase determination. The initial structure determination used the data between 20 and 13 A resolution, which was then extended one reciprocal lattice point at a time to 6.5 A resolution. At this point, a 3.5 A resolution data set compiled from a number of crystals collected at 277 K was introduced. Phase extension and averaging continued to 3.5 A resolution after re-determining the particle positions and orientations. The amino-acid sequences of most of the D, F and G proteins and part of the B protein could be unambiguously built into the 3.5 A electron-density map. Partial crystallographic refinement yielded an R factor of 31.6%, consistent with the relatively low resolution and lack of completeness of the data.

Bacteriophage phi X 174↗
PubMed1998

The structure of the two amino-terminal domains of human ICAM-1 suggests how it functions as a rhinovirus receptor and as an LFA-1 integrin ligand.

The normal function of human intercellular adhesion molecule-1 (ICAM-1) is to provide adhesion between endothelial cells and leukocytes after injury or stress. ICAM-1 binds to leukocyte function-associated antigen (LFA-1) or macrophage-1 antigen (Mac-1). However, ICAM-1 is also used as a receptor by the major group of human rhinoviruses and is a catalyst for the subsequent viral uncoating during cell entry. The three-dimensional atomic structure of the two amino-terminal domains (D1 and D2) of ICAM-1 has been determined to 2.2-A resolution and fitted into a cryoelectron microscopy reconstruction of a rhinovirus-ICAM-1 complex. Rhinovirus attachment is confined to the BC, CD, DE, and FG loops of the amino-terminal Ig-like domain (D1) at the end distal to the cellular membrane. The loops are considerably different in structure to those of human ICAM-2 or murine ICAM-1, which do not bind rhinoviruses. There are extensive charge interactions between ICAM-1 and human rhinoviruses, which are mostly conserved in both major and minor receptor groups of rhinoviruses. The interaction of ICAMs with LFA-1 is known to be mediated by a divalent cation bound to the insertion (I)-domain on the alpha chain of LFA-1 and the carboxyl group of a conserved glutamic acid residue on ICAMs. Domain D1 has been docked with the known structure of the I-domain. The resultant model is consistent with mutational data and provides a structural framework for the adhesion between these molecules.

Amino Acid Sequence↗
PubMed1998

A general phasing algorithm for multiple MAD and MIR data.

A phasing algorithm is presented for combining multiple wavelength anomalous dispersion (MAD) data from multiple types of anomalous scatterers, either in the same or in different derivative crystals, as well as for combining MAD data with multiple isomorphous replacement (MIR) data from different derivative crystals. A heavy-atom phasing and refinement program originally written by Rossmann [(1967) HATOMLSQ program, Purdue University, West Lafayette, Indiana, USA] has been modified to refine the parameters that define the anomalous and isomorphous scatterers and to determine protein phases by using all MAD and MIR derivatives simultaneously. The technique allows for appropriate weighting of every data set, including the native data, which contains neither an anomalous nor an isomorphous component. This method is a generalization of currently used heavy-atom methods. Numerical tests are presented for different experimental scenarios, including a double MAD experiment on the same crystal (diffraction data at two absorption edges), combination of two MAD experiments on different crystals, and combination of MAD data with MIR data from multiple crystals. An appendix shows how the Karle equations used in MAD phasing can be reformulated as a particular case of this algorithm.

Algorithms↗