1,721,031 research outputs found
Crystals of GlpE, a 12 kDa sulfurtransferase from Escherichia coli, display 1.06 Å resolution diffraction: a preliminary report
No full textThe Escherichia coli sn-glycerol 3-phosphate regulon contains the glpE gene coding for a 12 kDa protein which displays a sequence and a thiosulfate:cyanide sulfurtransferase activity similar to those of rhodanese enzymes. The GlpE protein was overexpressed, purified to homogeneity and crystallized in the trigonal space group P31 (or P32). The unit-cell parameters are a = b = 53.87, c = 30.52 A, gamma = 120°. Evaluation of the crystal packing parameter establishes the presence of one molecule per asymmetric unit, with a solvent content of 42%. The GlpE crystals display very high resolution diffraction; a 1.06 A data set was collected using synchrotron radiation (wavelength = 0.9102 A) with
an overall completeness of 99.6%
Escherichia coli GlpE is a prototype sulfurtransferase for the single-domain rhodanese homology superfamily
No full textBackground: Rhodanese domains are structural modules occurring in the three major evolutionary phyla. They are found as single-domain proteins, as tandemly repeated modules in which the C-terminal domain only bears the properly structured active site, or as members involvement in sulfur metabolism, or interaction with
of multidomain proteins. Although in vitro assays show sulfurtransferase or phosphatase activity associated with rhodanese or rhodanese-like domains, specific biological roles for most members of this homology superfamily have not been established.
Results: Eight ORFs coding for proteins consisting of (or containing) a rhodanese domain bearing the potentially catalytic Cys have been identified in the Escherichia coli K-12 genome. One of these codes for the 12-kDa protein GlpE, a member of the sn-glycerol 3-phoshate (glp) regulon. The crystal structure of GlpE, reported here at 1.06 A resolution, displays alpha/beta topology based on five beta-strands and five alpha-helices. The GlpE catalytic Cys residue is persulfurated and enclosed in a structurally conserved 5-residue loop in a region of positive electrostatic field.
Conclusions: Relative to the two-domain rhodanese of known three-dimensional structure, GlpE displays substantial shortening of loops connecting alpha-helices and beta-sheets, resulting in radical conformational changes surrounding the active site. As a consequence, GlpE is structurally more similar to Cdc25 phosphatase than to bovine or Azotobacter vinelandii rhodaneses. Sequence searches through completed genomes indicate that GlpE can be considered to be the prototype structure for the ubiquitous single-domain rhodanese module
Re-evaluation of amino acid sequence and structural consensus rules for cysteine-nitric oxide reactivity RID A-4573-2009
No full textNitric oxide (NO), produced in different cell types through the conversion of L-arginine into L-citrulline by the enzyme NO synthase, has been proposed to exert its action in several physiological and pathological events. The great propensity for nitrosothiol formation and breakdown represents a mechanism which modulates the action of macromolecules containing NO-reactive Cys residues at their active centre and/or allosteric sites. Based on the human haemoglobin (Hb) structure and accounting for the known acid-base catalysed Cys beta 93-nitrosylation and Cys beta 93NO-denitrosylation processes, the putative amino acid sequence (Lys/Arg/His/Asp/Glu)Cys(Asp/Glu) (sites -1, 0, and + 1, respectively) has been proposed as the minimum consensus motif for Cys-NO reactivity. Although not found in human Hb, the presence of a polar amino acid residue (Gly/Ser/Thr/Cys/Tyr/Asn/Gln) at the -2 position has been observed in some NO-reactive protein sequences (e.g., NMDA receptors). However, the most important component of the tri- or tetra-peptide consensus motif has been recognised as the Cys(Asp/Glu) pair [Stamler et at, Neuron (1997) 18, 691-696]. Here, we analyse the three-dimensional structure of several proteins containing NO-reactive Cys residues, and show that their nitrosylation and denitrosylation processes may depend on the Cys-Sy atomic structural microenvironment rather than on the tri- or tetra-peptide sequence consensus motif
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