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Xavier Robert

Publications and source records attributed to Xavier Robert.

3 recordsLinked to original sources

ESPript/ENDscript: Extracting and rendering sequence and 3D information from atomic structures of proteins.

The fortran program ESPript was created in 1993, to display on a PostScript figure multiple sequence alignments adorned with secondary structure elements. A web server was made available in 1999 and ESPript has been linked to three major web tools: ProDom which identifies protein domains, PredictProtein which predicts secondary structure elements and NPS@ which runs sequence alignment programs. A web server named ENDscript was created in 2002 to facilitate the generation of ESPript figures containing a large amount of information. ENDscript uses programs such as BLAST, Clustal and PHYLODENDRON to work on protein sequences and such as DSSP, CNS and MOLSCRIPT to work on protein coordinates. It enables the creation, from a single Protein Data Bank identifier, of a multiple sequence alignment figure adorned with secondary structure elements of each sequence of known 3D structure. Similar 3D structures are superimposed in turn with the program PROFIT and a final figure is drawn with BOBSCRIPT, which shows sequence and structure conservation along the Calpha trace of the query. ESPript and ENDscript are available at http://genopole.toulouse.inra.fr/ESPript.

DNA-Binding Proteins↗

The structure of barley alpha-amylase isozyme 1 reveals a novel role of domain C in substrate recognition and binding: a pair of sugar tongs.

Though the three-dimensional structures of barley alpha-amylase isozymes AMY1 and AMY2 are very similar, they differ remarkably from each other in their affinity for Ca(2+) and when interacting with substrate analogs. A surface site recognizing maltooligosaccharides, not earlier reported for other alpha-amylases and probably associated with the different activity of AMY1 and AMY2 toward starch granules, has been identified. It is located in the C-terminal part of the enzyme and, thus, highlights a potential role of domain C. In order to scrutinize the possible biological significance of this domain in alpha-amylases, a thorough comparison of their three-dimensional structures was conducted. An additional role for an earlier-identified starch granule binding surface site is proposed, and a new calcium ion is reported.

Acarbose↗

Expression, purification and preliminary crystallographic studies of alpha-amylase isozyme 1 from barley seeds.

The germinating barley seed contains two major alpha-amylase isozyme families, AMY1 and AMY2, involved in starch degradation to provide energy used by the plant embryo for growth. Many years of difficulty in growing three-dimensional crystals of natural AMY1 have now been overcome by a nonapeptide truncation of the enzyme C-terminus. The truncated enzyme was overexpressed in Pichia pastoris, purified and crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol 8000 as precipitant and 2-propanol as an additive. Crystals belong to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 88.36, b = 72.82, c = 61.74 A and one molecule per asymmetric unit.

Crystallography, X-Ray↗