The Radiation Hybrid Database.

Since July 1995, the European Bioinformatics Institute (EBI) has maintained RHdb, a public database for radiation hybrid data. Radiation hybrid data are used in the generation of alternative genetic maps as they can include non-polymorphic markers and are also powerful enough to order unresolved genetic clusters of polymorphic STSs. The EBI is an Outstation of the European Molecular Biology Laboratory (EMBL).     

Tertiary structure of two-electron reduced Megasphaera elsdenii flavodoxin and some implications, as determined by two-dimensional 1H-NMR and restrained molecular dynamics

The tertiary structure of the non-crystallizable two-electron-reduced Megasphaera elsdenii flavodoxin (15 kDa, 137 amino acid residues) has been determined using nuclear Overhauser enhancement restraints extracted from two-dimensional 1H-NMR spectra. A tertiary structure satisfying the experimental restraints very well (maximum NOE violation of 66 pm) was obtained with use of restrained molecular dynamics, using 509 distance restraints (including one non-NOE) on a starting structure modeled from the crystal structure of one-electron-reduced Clostridium MP flavodoxin. The protein consists of a central parallel beta-sheet surrounded on both sides by two alpha-helices. The flavin is positioned at the periphery of the molecule. The tertiary structure of the protein is highly defined with the exception of the flavin. The latter is expected to result from performing the restrained molecular dynamics simulation without water molecules and without proper charges on the flavin. The flavin, including the phosphate, the ribityl side chain and the isoalloxazine ring, is solvent accessible under the experimental conditions used and evidenced by a two-dimensional amide exchange experiment. This accessibility is expected to be important in the redox potential regulation of the semiquinone/hydroquinone couple of the protein. The amide exchange against deuterons and several typical line shapes in the two-dimensional NMR spectra are consistent with the structure generated. The structure is discussed in detail.     

Hydrophobic patches on the surfaces of protein structures

A survey of hydrophobic patches on the surface of 112 soluble, monomeric proteins is presented. The largest patch on each individual protein averages around 400 Ų but can range from 200 to 1,200 Ų. These areas are not correlated to the sizes of the proteins and only weakly to their apolar surface fraction. Ala, Lys, and Pro have dominating contributions to the apolar surface for smaller patches, while those of the hydrophobic amino acids become more important as the patch size Increases. The hydrophilic amino acids expose an approximately constant fraction of their apolar area independent of patch size; the hydrophobic residue types reach similar exposure only in the larger patches. Though the mobility of residues on the surface is generally higher, it decreases for hydrophilic residues with Increasing patch size. Several characteristics of hydrophobic patches catalogued here should prove useful in the design and engineering of proteins. © 1996 Wiley-Liss, Inc.     

A method for detecting hydrophobic patches on protein surfaces

A method for the detection of hydrophobic patches on the surfaces of protein tertiary structures is presented. It delineates explicit contiguous pieces of surface of arbitrary size and shape that consist solely of carbon and sulphur atoms using a dot representation of the solvent-accessible surface. The technique is also useful in detecting surface segments with other characteristics, such as polar patches. Its potential as a tool in the study of protein-protein interactions and substrate recognition is demonstrated by applying the method to myoglobin, Leu/Ile/Val-binding protein, lipase, lysozyme, azurin, triose phosphate isomerase, carbonic anhydrase, and phosphoglycerate kinase. Only the largest patches, having sizes exceeding random expectation, are deemed meaningful. In addition to well-known hydrophobic patches on these proteins, a number of other patches are found, and their significance is discussed. The method is simple, fast, and robust. The program text is obtainable by anonymous ftp. © 1996 Wiley-Liss, Inc.     

On defining the dynamics of hydrophobic patches on protein surfaces

We present a simple and efficient method called PATCHTRACK, for studying the dynamics of hydrophobic surface patches. It tracks the patches on snapshot structures taken from a Molecular Dynamics simulation. They are connected into so-called patch runs, which are subsequently clustered into so-called recurrent patches. The method is applied to simulations of three different proteins. Protein motion causes addition and removal of one or more atoms to a patch, resulting in size fluctuations of around 25%. The fluctuations eventually lead to the break-up of a patch, and their average life span is therefore remarkably short at around 4 ps. However, some patch runs are much more stable, lasting hundreds of picoseconds. One such case is the largest patch in amicyanin that is known to be biologically relevant. Another case, previously not reported, is found in phospholipase A(2), where the functional significance of a large recurrent patch formed by Leu58 and Phe94 seems likely. This patch appears to have been overlooked as it is relatively small in the X-ray structure, demonstrating the utility of the current method. The most frequently occurring patch size is 40-60 A(2), but sizes of up to 500 A(2) are also observed. There is no clear relation between patch run durations and their average size. However, long-lasting patch runs tend not to have large fluctuations. The recurrent patches have alternating periods of "liveness" and "dormancy"; around 25% of them is predominantly in the live state.     

Molecular mechanisms that distinguish TFIID housekeeping from regulatable SAGA promoters

An important distinction is frequently made between constitutively expressed housekeeping genes versus regulated genes. Although generally characterized by different DNA elements, chromatin architecture and cofactors, it is not known to what degree promoter classes strictly follow regulatability rules and which molecular mechanisms dictate such differences. We show that SAGA‐dominated/TATA‐box promoters are more responsive to changes in the amount of activator, even compared to TFIID/TATA‐like promoters that depend on the same activator Hsf1. Regulatability is therefore an inherent property of promoter class. Further analyses show that SAGA/TATA‐box promoters are more dynamic because TATA‐binding protein recruitment through SAGA is susceptible to removal by Mot1. In addition, the nucleosome configuration upon activator depletion shifts on SAGA/TATA‐box promoters and seems less amenable to preinitiation complex formation. The results explain the fundamental difference between housekeeping and regulatable genes, revealing an additional facet of combinatorial control: an activator can elicit a different response dependent on core promoter class.     

A proposal for a standard CORBA interface for genome maps

MOTIVATION: The scientific community urgently needs to standardize the exchange of biological data. This is helped by the use of a common protocol and the definition of shared data structures. We have based our standardization work on CORBA, a technology that has become a standard in the past years and allows interoperability between distributed objects. RESULTS: We have defined an IDL specification for genome maps and present it to the scientific community. We have implemented CORBA servers based on this IDL to distribute RHdb and HuGeMap maps. The IDL will co-evolve with the needs of the mapping community. AVAILABILITY: The standard IDL for genome maps is available at http:// corba.ebi.ac.uk/RHdb/EUCORBA/MapIDL.htm l. The IORs to browse maps from Infobiogen and EBI are at http://www.infobiogen.fr/services/Hugemap/IOR and http://corba.ebi.ac.uk/RHdb/EUCORBA/IOR CONTACT: manu@infobiogen.fr, tome@ebi.ac.uk     

Accessing and distributing EMBL data using CORBA (common object request broker architecture)

Background  

The EMBL Nucleotide Sequence Database is a comprehensive database of DNA and RNA sequences and related information traditionally made available in flat-file format. Queries through tools such as SRS (Sequence Retrieval System) also return data in flat-file format. Flat files have a number of shortcomings, however, and the resources therefore currently lack a flexible environment to meet individual researchers' needs. The Object Management Group's common object request broker architecture (CORBA) is an industry standard that provides platform-independent programming interfaces and models for portable distributed object-oriented computing applications. Its independence from programming languages, computing platforms and network protocols makes it attractive for developing new applications for querying and distributing biological data.