Structure-function relationships in hydrophobins:Probing the role of charged side chains

Hydrophobins are small fungal proteins that are amphiphilic and have a strong tendency to assemble at interfaces. By taking advantage of this property, hydrophobins have been used for a number of applications: as affinity tags in protein purification, for protein immobilization, such as in foam stabilizers, and as dispersion agents for insoluble drug molecules. Here, we used site-directed mutagenesis to gain an understanding of the molecular basis of their properties. We especially focused on the role of charged amino acids in the structure of hydrophobins. For this purpose, fusion proteins consisting of Trichoderma reesei hydrophobin I (HFBI) and the green fluorescent protein (GFP) that contained various combinations of substitutions of charged amino acids (D30, K32, D40, D43, R45, K50) in the HFBI structure were produced. The effects of the introduced mutations on binding, oligomerization, and partitioning were characterized in an aqueous two-phase system. It was found that some substitutions caused better surface binding and reduced oligomerization, while some showed the opposite effects. However, all mutations decreased partitioning in surfactant systems, indicating that the different functions are not directly correlated and that partitioning is dependent on finely tuned properties of hydrophobins. This work shows that not all functions in self-assembly are connected in a predictable way and that a simple surfactant model for hydrophobin function is insufficient

O Tama A 'Aiga: the politics of succession to Samoa's paramount titles

Samoa’s indigenous political system is based on the symbiotic relationship between two related but distinct aspects of custom; local practice (aga’ifanua)and universal custom (aganu’u). How are they defined and negotiated by families, village council, church and the Land and Titles Court? How is the past re-presented for present and future purposes, and what are the socio-economic consequences for families, village council, church and nation who are trying to develop. In examining the interface between political history and socio-economic imperatives, the author draws on succession disputes to Samoa’s paramount titles, known collectively as the Tama’āiga. The disputes are complicated in themselves. The complications are compounded by a society that continues to rely on oral traditions to articulate inherited rank on one hand and a written constitution as the source of new authority on the other. He concludes that the prospect of transcending neo-traditional conservatism may be remote. The debate engendered by this important book concerns both a political system developed for the needs of a bygone oral-based era, and the plight of a small developing country experiencing the relentless onslaught of economic globalization. Without unfolding and reconciling longstanding political intrigues embedded in contested pasts, in their rush to embrace globalization, Islanders may find themselves in a position where they are brushed aside. The tension between local practice (aga’ifanua,) custom (aganu’u) and development (atina’e) is not new, but the issues arising are so fraught with controversy that few, if any, have the courage to face them. But author Tuimaleali’ifano, who himself declined to accept a paramount title, argues that failure to confront them means mortgaging the inheritance of Samoa’s successive generations, continued dependency on foreign aid and the demoralizing drain of Samoa’s enthusiastic and energetic people to her more affluent overseas neighbors