NMR chemical shift and relaxation measurements provide evidence for the coupled folding and binding of the p53 transactivation domain

The interaction between the acidic transactivation domain of the human tumor suppressor protein p53 (p53TAD) and the 70 kDa subunit of human replication protein A (hRPA70) was investigated using heteronuclear magnetic resonance spectroscopy. A (1)H–(15)N heteronuclear single quantum coherence (HSQC) titration experiment was performed on a (15)N-labeled fragment of hRPA70, containing the N-terminal 168 residues (hRPA70(1–168)) and p53TAD. HRPA70(1–168) residues important for binding were identified and found to be localized to a prominent basic cleft. This binding site overlapped with a previously identified single-stranded DNA-binding site, suggesting that a competitive binding mechanism may regulate the formation of p53TAD–hRPA70 complex. The amide (1)H and (15)N chemical shifts of an uniformly (15)N-labeled sample of p53TAD were also monitored before and after the addition of unlabeled hRPA70(1–168). In the presence of unlabeled hRPA70(1–168), resonance lineshapes increased and corresponding intensity reductions were observed for specific p53TAD residues. The largest intensity reductions were observed for p53TAD residues 42–56. Minimal binding was observed between p53TAD and a mutant form of hRPA70(1–168), where the basic cleft residue R41 was changed to a glutamic acid (R41E), demonstrating that ionic interactions play an important role in specifying the binding interface. The region of p53TAD most affected by binding hRPA70(1–168) was found to have some residual alpha helical and beta strand structure; however, this structure was not stabilized by binding hRPA70(1–168). (15)N relaxation experiments were performed to monitor changes in backbone dynamics of p53TAD when bound to hRPA70(1–168). Large changes in both the transverse (R(2)) and rotating frame (R(1ρ)) relaxation rates were observed for a subset of the p53TAD residues that had (1)H–(15)N HSQC resonance intensity reductions during the complex formation. The folding of p53TAD upon complex formation is suggested by the pattern of changes observed for both R(2) and R(1ρ). A model that couples the formation of a weak encounter complex between p53TAD and hRPA70(1–168) to the folding of p53TAD is discussed in the context of a functional role for the p53–hRPA70 complex in DNA repair

Auswirkungen von Komplexität auf die Performance von Produktionsgruppen

The increase in complexity in production systems represents one of the major challenges for manufacturing companies. In this dissertation, possible effects of complexity on the performance of production groups are examined. Six studies are carried out, which build on each other in terms of content and methodology and thus cover a complete research process from the initial definition of key concepts up to the derivation of design recommendations for operational practice. Within the exploratory phase, a qualitative interview study is conducted in order to identify drivers of the phenomenon of complexity in digitalized work systems. Based on two systematic literature studies, the state of research on (1) complexity models and (2) group performance models in the context of production systems is examined in a structured way and the existing research deficit is pointed out. On the basis of the preliminary studies, a hypothetical model is developed to explain the performance of production groups. The model includes different complexity dimensions in addition to known influencing variables from team research. The operationalization of the latent variables is carried out with a further qualitative interview study. The group performance model is empirically evaluated in a questionnaire study (n = 455) using the method of structural equation modelling. On the one hand, the results of the statistical analysis show that there is a positive relationship between task complexity and group performance, which is mediated by the quality of teamwork. On the other hand, a negative relationship is identified between the complexity of group design and group performance, which is also mediated by the quality of teamwork. The findings are used to derive specific recommendations for the complexity-related design of group work in production. In addition, a metric to capture the complexity of the work process of production groups is developed and evaluated in a simulation study. The metric is applicable in early planning phases of production systems. The resulting complexity level for the production group can be used for a comparative analysis of organizational design options. Furthermore, the effects of different group qualification profiles on the complexity level or performance of a production group can be assessed

Characterization of Two Small RNAs of Streptococcus mutans UA159

Small RNAs (sRNA) regulate several processes including metalloregulation, acid-tolerance, biofilm formation, and virulence. Streptococcus mutans UA159 is an etiological agent of dental caries. Several sRNAs were found in intergenic regions of S. mutans and two were characterized. The first characterized sRNA, SurC, was located within the loci between dnaK and dnaJ (~190 nucleotides) and was developmentally regulated. The second characterized sRNA, MrrC (~420 nucleotides), a metal responsive RNA was located between pyrG and fbaA. In THYE, there was no change observed in growth rate for either ΔSurC and ΔMrrC. In chemically defined medium, the growth rate of ΔMrrC was significantly reduced at pH 5.0 and in 4.0% ethanol. Both ΔSurC and ΔMrrC contain defects in biofilm formation, acid tolerance response, and transformation frequency. Identification of sRNAs and understanding their function within S. mutans is necessary to provide insight into the molecular control of virulence for this caries forming organism.M.Sc

Characterization of pellicle inhibition in Gluconacetobacter xylinus 53582 by a small molecule, pellicin, identified by a chemical genetics screen.

Pellicin ([2E]-3-phenyl-1-[2,3,4,5-tetrahydro-1,6-benzodioxocin-8-yl]prop-2-en-1-one) was identified in a chemical genetics screen of 10,000 small molecules for its ability to completely abolish pellicle production in Gluconacetobacter xylinus. Cells grown in the presence of pellicin grew 1.5 times faster than untreated cells. Interestingly, growth in pellicin also caused G. xylinus cells to elongate. Measurement of cellulose synthesis in vitro showed that cellulose synthase activity was not directly inhibited by pellicin. Rather, when cellulose synthase activity was measured in cells that were pre-treated with the compound, the rate of cellulose synthesis increased eight-fold over that observed for untreated cells. This phenomenon was also apparent in the rapid production of cellulose when cells grown in the presence of pellicin were washed and transferred to media lacking the inhibitor. The rate at which cellulose was produced could not be accounted for by growth of the organism. Pellicin was not detected when intracellular contents were analyzed. Furthermore, it was found that pellicin exerts its effect extracellularly by interfering with the crystallization of pre-cellulosic tactoidal aggregates. This interference of the crystallization process resulted in enhanced production of cellulose II as evidenced by the ratio of acid insoluble to acid soluble product in in vitro assays and confirmed in vivo by scanning electron microscopy and powder X-ray diffraction. The relative crystallinity index, RCI, of pellicle produced by untreated G. xylinus cultures was 70% while pellicin-grown cultures had RCI of 38%. Mercerized pellicle of untreated cells had RCI of 42%, which further confirms the mechanism of action of pellicin as an inhibitor of the cellulose I crystallization process. Pellicin is a useful tool for the study of cellulose biosynthesis in G. xylinus

Transformation of Working Environments Through Digitalization : Exploration and Systematization of Complexity Drivers

Digitalization has a significant impact on our working life and it allows whole industries to rethink their value chains. This paper examines how digitalization relates to complexity in work systems with respect to relevant organizational fields of work organization. 23 semi-structured interviews with experts from science and economy were conducted and analyzed. Key findings are that digitalization has far-reaching, interrelated implications for all organizational fields. Moreover, digitalization-related aspects were identified which have the potential to increase complexity in work systems