On the role of the two extracytoplasmic substrate-binding domains in the ABC transporter OpuA

Members of two transporter families of the ATP-binding cassette (ABC) superfamily use two or even four extracytoplasmic substrate-binding domains (SBDs) for transport. We report on the role of the two SBDs in the translocation cycle of the ABC transporter OpuA from Lactococcus lactis. Heterooligomeric OpuA complexes with only one SBD or one functional and one non-functional SBD (inactivated by covalent linkage of a substrate mimic) have been constructed, and the substrate binding and transport kinetics of the purified transporters, reconstituted in liposomes, have been determined. The data indicate that the two SBDs of OpuA interact in a cooperative manner in the translocation process by stimulating either the docking of the SBDs onto the translocator or the delivery of glycine betaine to the translocator. It appears that one of these initial steps, but not the later steps in translocation or resetting of the system to the initial state, is rate determining for transport. These new insights on the functional role of the extracytoplasmic SBDs are discussed in the light of the current knowledge of substrate-binding-protein-dependent ABC transporters

Assessing multifunctional innovation adoption via an integrative model

This study proposes and tests an integrative model that incorporates the mental resources framework (MOA: motivation, opportunity, and ability) alongside traditional innovation adoption predictors for assessing the adoption of dual-functionality innovations (DFI), a special case of multifunctional innovations (MFI). The multifunctional nature of an increasing number of new products demands the use of mental resources in evaluating new offers, as the comprehension of MFIs is more demanding (i.e., requires more mental resources) than singlefunctionality (SF) products. The proposed model also recognizes the role of MFI categorization as a critical link in the process, because an MFI, and within the context of our study a DFI, helps consumers achieve multiple goals if they realize its dual functionality. Our model demonstrates that mental resources play a significant role in consumers’ adoption decisions and should be included in studies of MFI adoption. Further, our integrative model offers a significant improvement over rival alternatives that use only traditional innovation adoption predictors. Thus, the model offers a new approach for estimating MFI adoption with a superior predictive power and facilitates the development of appropriate marketing strategies for such products.Product Innovation ManagementIndustrial Design Engineerin