21 research outputs found
Regulating histone acetyltransferases and deacetylases
Histone acetyltransferases and histone deacetylases regulate the acetylation of histones and transcription factors, and in doing so have major roles in the control of cell fate. Many recent results have indicated that their function is strictly regulated in cells through the modulation of their levels, activity and availability for interaction with specific transcription factors. In this review, we present the various molecular mechanisms that bring about this tight regulation and discuss how these regulatory events influence cellular responses to environmental changes
Crystal Structure of Bacillus anthracis Phosphoglucosamine Mutase, an Enzyme in the Peptidoglycan Biosynthetic Pathway ▿†
Phosphoglucosamine mutase (PNGM) is an evolutionarily conserved bacterial enzyme that participates in the cytoplasmic steps of peptidoglycan biosynthesis. As peptidoglycan is essential for bacterial survival and is absent in humans, enzymes in this pathway have been the focus of intensive inhibitor design efforts. Many aspects of the structural biology of the peptidoglycan pathway have been elucidated, with the exception of the PNGM structure. We present here the crystal structure of PNGM from the human pathogen and bioterrorism agent Bacillus anthracis. The structure reveals key residues in the large active site cleft of the enzyme which likely have roles in catalysis and specificity. A large conformational change of the C-terminal domain of PNGM is observed when comparing two independent molecules in the crystal, shedding light on both the apo- and ligand-bound conformers of the enzyme. Crystal packing analyses and dynamic light scattering studies suggest that the enzyme is a dimer in solution. Multiple sequence alignments show that residues in the dimer interface are conserved, suggesting that many PNGM enzymes adopt this oligomeric state. This work lays the foundation for the development of inhibitors for PNGM enzymes from human pathogens
Solution NMR of a 463-Residue Phosphohexomutase: Domain 4 Mobility, Substates, and Phosphoryl Transfer Defect
Phosphomannomutase/phosphoglucomutase contributes to
the infectivity
of <i>Pseudomonas aeruginosa</i>, retains and reorients
its intermediate by 180°, and rotates domain 4 to close the deep
catalytic cleft. Nuclear magnetic resonance (NMR) spectra of the backbone
of wild-type and S108C-inactivated enzymes were assigned to at least
90%. <sup>13</sup>C secondary chemical shifts report excellent agreement
of solution and crystallographic structure over the 14 α-helices,
C-capping motifs, and 20 of the 22 β-strands. Major and minor
NMR peaks implicate substates affecting 28% of assigned residues.
These can be attributed to the phosphorylation state and possibly
to conformational interconversions. The S108C substitution of the
phosphoryl donor and acceptor slowed transformation of the glucose
1-phosphate substrate by impairing <i>k</i><sub>cat</sub>. Addition of the glucose 1,6-bisphosphate intermediate accelerated
this reaction by 2–3 orders of magnitude, somewhat bypassing
the defect and apparently relieving substrate inhibition. The S108C
mutation perturbs the NMR spectra and electron density map around
the catalytic cleft while preserving the secondary structure in solution.
Diminished peak heights and faster <sup>15</sup>N relaxation suggest
line broadening and millisecond fluctuations within four loops that
can contact phosphosugars. <sup>15</sup>N NMR relaxation and peak
heights suggest that domain 4 reorients slightly faster in solution
than domains 1–3, and with a different principal axis of diffusion.
This adds to the crystallographic evidence of domain 4 rotations in
the enzyme, which were previously suggested to couple to reorientation
of the intermediate, substrate binding, and product release
Solution NMR of a 463-Residue Phosphohexomutase: Domain 4 Mobility, Substates, and Phosphoryl Transfer Defect
Phosphomannomutase/phosphoglucomutase contributes to
the infectivity
of <i>Pseudomonas aeruginosa</i>, retains and reorients
its intermediate by 180°, and rotates domain 4 to close the deep
catalytic cleft. Nuclear magnetic resonance (NMR) spectra of the backbone
of wild-type and S108C-inactivated enzymes were assigned to at least
90%. <sup>13</sup>C secondary chemical shifts report excellent agreement
of solution and crystallographic structure over the 14 α-helices,
C-capping motifs, and 20 of the 22 β-strands. Major and minor
NMR peaks implicate substates affecting 28% of assigned residues.
These can be attributed to the phosphorylation state and possibly
to conformational interconversions. The S108C substitution of the
phosphoryl donor and acceptor slowed transformation of the glucose
1-phosphate substrate by impairing <i>k</i><sub>cat</sub>. Addition of the glucose 1,6-bisphosphate intermediate accelerated
this reaction by 2–3 orders of magnitude, somewhat bypassing
the defect and apparently relieving substrate inhibition. The S108C
mutation perturbs the NMR spectra and electron density map around
the catalytic cleft while preserving the secondary structure in solution.
Diminished peak heights and faster <sup>15</sup>N relaxation suggest
line broadening and millisecond fluctuations within four loops that
can contact phosphosugars. <sup>15</sup>N NMR relaxation and peak
heights suggest that domain 4 reorients slightly faster in solution
than domains 1–3, and with a different principal axis of diffusion.
This adds to the crystallographic evidence of domain 4 rotations in
the enzyme, which were previously suggested to couple to reorientation
of the intermediate, substrate binding, and product release