The C-terminal domain of full-length E-coli SSB is disordered even when bound to DNA

The crystal structure of full-length homotetrameric single-stranded DNA (ssDNA)-binding protein from Escherichia coli (SSB) has been determined to 3.3 Angstrom resolution and reveals that the entire C-terminal domain is disordered even in the presence of ssDNA. To our knowledge, this is the first experimental evidence that the C-terminal domain of SSB may be inherently disordered. The N-terminal DNA-binding domain of the protein is well ordered and is virtually indistinguishable from the previously determined structure of the chymotryptic fragment of SSB (SSBc) in complex with ssDNA. The absence of observable interactions with the core protein and the crystal packing of SSB together suggest that the disordered C-terminal domains likely extend laterally away from the DNA- binding domains, which may facilitate interactions with components of the replication machinery in vivo. The structure also reveals the conservation of molecular contacts between successive tetramers mediated by the L-45 loops as seen in two other crystal forms of SSBc, suggesting a possible functional relevance of this interaction

Prioritised fuzzy constraint satisfaction problems: axioms, instantiation and validation

This paper identifies a generic axiom framework for prioritised fuzzy constraint satisfaction problems (PFCSPs), and proposes methods to instantiate it (i.e., to construct specific schemes which obey the generic axiom framework). In particular, we give five methods to construct the priority operators that are used for calculating the local satisfaction degree of a prioritised fuzzy constraint, and identify priority T-norm operators that can be used for calculating the global satisfaction degree of a prioritised fuzzy constraint problem. Moreover, a number of numerical examples and real examples are used to validate our system, and thus we further obtain some insights into our system. In addition, we explore the relationship between weight schemes and prioritised FCSP schemes, and reveal that the weighted FCSP schemes are the dual of prioritised FCSP schemes, which can, correspondingly, be called posterioritised FCSP schemes