Structural basis of L-phosphoserine binding to Bacillus alcalophilus phosphoserine aminotransferase.

Phosphoserine aminotransferase is a vitamin B6-dependent enzyme that catalyzes the reversible conversion of 3-phosphohydroxypyruvate to L-phosphoserine using glutamate as an amine donor. In an effort to gain insight into the substrate-recognition mechanism of the enzyme, crystal structures of Bacillus alcalophilus phosphoserine aminotransferase in the presence or absence of L-phosphoserine were determined to resolutions of 1.5 and 1.

Conserved hydrophobic clusters on the surface of the Caf1A usher C-terminal domain are important for F1 antigen assembly.

The outer membrane usher protein Caf1A of the plague pathogen Yersinia pestis is responsible for the assembly of a major surface antigen, the F1 capsule. The F1 capsule is mainly formed by thin linear polymers of Caf1 (capsular antigen fraction 1) protein subunits. The Caf1A usher promotes polymerization of subunits and secretion of growing polymers to the cell surface.

Effect of pH on the structure and stability of Bacillus circulans ssp. alkalophilus phosphoserine aminotransferase: thermodynamic and crystallographic studies.

pH is one of the key parameters that affect the stability and function of proteins. We have studied the effect of pH on the pyridoxal-5'-phosphate-dependent enzyme phosphoserine aminotransferase produced by the facultative alkaliphile Bacillus circulans ssp. alkalophilus using thermodynamic and crystallographic analysis.

Strain relief at the active site of phosphoserine aminotransferase induced by radiation damage.

The X-ray susceptibility of the lysine-pyridoxal-5'-phosphate Schiff base in Bacillus alcalophilus phosphoserine aminotransferase has been investigated using crystallographic data collected at 100 K to 1.3 A resolution, complemented by on-line spectroscopic studies. X-rays induce deprotonation of the internal aldimine, changes in the Schiff base conformation, displacement of the cofactor molecule, and disruption of the Schiff base linkage between pyridoxal-5'-phosphate and the Lys residue.

Enzyme adaptation to alkaline pH: atomic resolution (1.08 A) structure of phosphoserine aminotransferase from Bacillus alcalophilus.

The crystal structure of the vitamin B(6)-dependent enzyme phosphoserine aminotransferase from the obligatory alkaliphile Bacillus alcalophilus has been determined at 1.08 A resolution. The model was refined to an R-factor of 11.

Expression, purification, crystallization and preliminary crystallographic analysis of phosphoserine aminotransferase from Bacillus alcalophilus.

Phosphoserine aminotransferase (PSAT; EC 2.6.1.

Antiferritin VL homodimer binds human spleen ferritin with high specificity.

The antiferritin variable light domain (VL) dimer binds human spleen ferritin ( approximately 85% L subunits) but with approximately 50-fold lower affinity, K(a)=4 x 10(7) x M(-1), than the parent F11 antibody (K(a)=2.1 x 10(9) x M(-1)). The VL dimer does not recognize either rL (100% L subunits) or rH (100% H subunits) human ferritin, whereas the parent antibody recognizes rL-ferritin.

Partially structured state of the functional VH domain of the mouse anti-ferritin antibody F11.

An antibody combining site generally involves the two variable domains, VH from the heavy and VL from the light chain. We expressed the individual VH domain of the mouse anti-human ferritin monoclonal antibody F11. The loss of affinity was not dramatic (K(a)=4.

Amyloid fibril formation of the mouse V(L) domain at acidic pH.

The recombinant V(L) domain that represents the variable part of the light chain (type kappa) of mouse monoclonal antibody F11 directed against human spleen ferritin was found to form amyloid fibrils at acidic pH as evidenced by electron microscopy, thioflavin T binding, and apple-green birefringence after Congo red staining. This is the first demonstration of amyloid fibril formation of the mouse V(L) domain. To understand the mechanism of acidic pH-induced amyloid fibril formation, conformational changes of the V(L) domain were studied by one-dimensional NMR, differential scanning calorimetry, analytical ultracentrifugation, hydrophobic dye binding, far-UV circular dichroism, and tryptophan fluorescence.