In this issue

2410 The crystal structure of the AF2331 protein from Archaeoglobus fulgidus DSM 4304 forms an unusual interdigitated dimer with a new type of α+β fold

Shuren Wang, Olga Kirillova, Maksymilian Chruszcz, Dominik Gront, Matthew D. Zimmerman, Marcin T. Cymborowski, Igor A. Shumilin, Tatiana Skarina, Elena Gorodichtchenskaia, Alexei Savchenko, Aled M. Edwards, and Wladek Minor

The structure of AF2331, an orphan protein of unknown function from Archaeoglobus fulgidus, forms an unusual homodimer, where the two core β-sheets are interdigitated, containing strands alternating from both subunits. AF2331 forms a novel α+β fold, and is the sole member of a new fold, superfamily and family in the PFAM fold classification scheme. The decrease in solvent-accessible surface area upon dimerization is unusually large (3960 Ų) for a protein of its size. AF2331 contains multiple negatively-charged surface clusters, and is located on the same operon as the basic protein AF2330, which suggests that AF2331 and AF2330 may form a charge-stabilized complex in vivo.

2231 A kinetic assessment of the C. elegans amyloid disaggregation activity enables uncoupling of disassemblyand proteolysis

Jan Bieschke, Ehud Cohen, Amber Murray, Andrew Dillin, and Jeffery W. Kelly

Amyloid beta (Aβ) aggregation linked to proteotoxicity appears to cause Alzheimer's disease. Kelly and co-workers previously reported a disaggregation and proteolytic activity that reduces Abeta proteotoxicity in a Caenorhabditis elegans Alzheimer's model. In this study, the authors demonstrate that the C. elegans Aβ disaggregation and proteolysis activities are separable, in that protease inhibition does not disable aggregation. Moreover, they show that one or more protein is required for the Aβ fibril disaggregation activity (blue trace), as pretreatment with proteinase K (red) eliminates the disaggregase activity.

2403 KiNG (Kinemage, Next Generation): A versatile interactive molecular and scientific visualization program

Vincent B. Chen, Ian W. Davis, and David C. Richardson

The program KiNG represents the current stage in the development of kinemage graphics, originally launched along with the first issue of Protein Science. KiNG is a versatile and powerful Java-based scientific software package that uses kinemage interactive 3D graphics for visualizing and analyzing not just structures of biological molecules, but also other types of scientific information. The features of KiNG make it particularly suitable for use in research, as well as for scientific illustration, graphics production, and education. KiNG is freely available from http://kinemage.biochem.duke.edu for use on all major operating systems and as a web applet.

2316 One-plasmid tunable coexpression for mycobacterial protein-protein interaction studies

Yong Chang, David Mead, Vinay Dhodda, Phil Brumm, and Brian G. Fox

The development of new tools for the study of mycobacterial protein interactions is timely because tuberculosis, caused by the human pathogen Mycobacterium tuberculosis, is one of the world's deadliest diseases. In this work, the authors report the construction of a single plasmid system that allows controlled, tunable co-expression of protein complexes in mycobacteria and demonstrate its utility with reporter proteins and a two-protein enzyme complex. The developed vector system and co-expression strategy should be applicable in other species, and can thus help to expand options for study of protein-protein interactions, one of the outstanding challenges of proteomics research.