Pectin methyl esterase inhibits intrusive and symplastic cell growth in developing wood cells of Populus.

Wood cells, unlike most other cells in plants, grow by a unique combination of intrusive and symplastic growth. Fibers grow in diameter by diffuse symplastic growth, but they elongate solely by intrusive apical growth penetrating the pectin-rich middle lamella that cements neighboring cells together. In contrast, vessel elements grow in diameter by a combination of intrusive and symplastic growth.

GuHCl and NaCl-dependent hydrogen exchange in MerP reveals a well-defined core with an unusual exchange pattern.

We have analysed hydrogen exchange at amide groups to characterise the energy landscape of the 72 amino acid residue protein MerP. From the guanidine hydrochloride (GuHCl) dependence of exchange in the pre-transitional region we have determined free energy values of exchange (DeltaG(HX)) and corresponding m-values for individual amide protons. Detailed analysis of the exchange patterns indicates that for one set of amide protons there is a weak dependence on denaturant, indicating that the exchange is dominated by local fluctuations.

NMR studies of interactions between periplasmic chaperones from uropathogenic E. coli and pilicides that interfere with chaperone function and pilus assembly.

Adherence of uropathogenic Escherichia coli to host tissue is mediated by pili, which are hair-like protein structures extending from the outer cell membrane of the bacterium. The chaperones FimC and PapD are key components in pilus assembly since they catalyse folding of subunits that are incorporated in type 1 and P pili, respectively, and also transport the subunits across the periplasmic space. Recently, compounds that inhibit pilus biogenesis and interfere with chaperone-subunit interactions have been discovered and termed pilicides.

Transient interaction with nanoparticles "freezes" a protein in an ensemble of metastable near-native conformations.

It is well-known that adsorption of proteins on interfaces often induces substantial alterations of the protein structure. However, very little is known about whether these conformational changes have any consequence for the protein conformation after desorption from the interface. To investigate this matter, we have selected a protein-particle system in which the enzyme human carbonic anhydrase I (HCAI) alternates between the adsorbed and free state upon interaction with the silica nanoparticles.