A tale of tails: deciphering the contribution of terminal tails to the biochemical properties of two Dps proteins from Streptomyces coelicolor

Dps proteins are members of an extensive family of proteins that oxidise and deposit iron in the form of ferric oxide, and are also able to bind DNA. Ferroxidation centres are formed at the interface of anti-parallel dimers, which further assemble into dodecameric nanocages with a hollow core where ferric oxide is deposited. Streptomyces coelicolor encodes three Dps-like proteins (DpsA, B and C). Despite sharing the conserved four-helix bundle organisation observed in members of the Dps family, they display significant differences in the length of terminal extensions, or tails. DpsA possess both N- and C-terminal tails of different lengths, and their removal affects quaternary structure assembly to varying degrees. DpsC quaternary structure, on the other hand, is heavily dependent on its N-terminal tail as its removal abolishes correct protein folding. Analysis of the crystal structure of dodecamers from both proteins revealed remarkable differences in the position of tails and interface surface area; and provides insight to explain the differences in biochemical behaviour observed while comparing DpsA and DpsC.     

The modernity of Dedekind’s anticipations contained in What are numbers and what are they good for?

Archive for History of Exact Sciences - We show that Dedekind, in his proof of the principle of definition by mathematical recursion, used implicitly both the concept of an inductive cone from an...     

Timing of mitosis in Physarum polycephalum: effects of agents affecting cyclic AMP concentrations.

Cultures of Physarum polycephalum incubated with caffeine or theophylline for over 100 min prior to mitosis exhibited mitotic delay proportional to the time of treatment before 100 min. Starved cultures exhibited mitotic delay at times of starvation longer than 180 min and slight stimulation from 100-180 min. Dibutyryl cAMP appeared to accelerate reconstruction of the nucleus following mitosis.     

The sensitivity to plasmin digestion of human IgG proteins of different heavy chain subclasses.

Normal IgG and purified IgG proteins of all 4 subclasses were digested with plasmin. As expected, IgG3 proteins were highly susceptible to degradation. Usually, activation with streptokinase resulted in faster and more accentuated degradation, but normal IgG was more intensely degraded by nonactivated plasmin. The presence of plasmin activators in IgG preparation might account for this observation.     

Spin label studies of ATP phosphoribosyltransferase of E. coli.

Covalently bound bromoacetamide nitroxides have been used to detect the conformational changes and enzyme association induced by its feedback inhibitor, histidine.