Functional importance of αIle-346 and αIle-348 in the catalytic sites of Escherichia coli ATP synthase.

We studied the functional role of highly conserved VISIT-DG sequence residues αIle-346 and αIle-348 in the catalytic sites of Escherichia coli F1Fo ATP synthase. αIle-346 is in close proximity, 2.98 and 3.63 Å, to the two known phosphate binding residues αR376 and ßR182; αIle-348 is situated within 3.66 Å from ßR182. Single or double mutants of both αI346 and αI348 resulted in a variable loss of oxidative phosphorylation and ATPase activity. Azide, fluoroaluminate, and fluoroscandium caused insignificant to significant inhibition of mutants. Whereas the wild-type enzyme was completely inhibited by NBD-Cl (7-chloro-4-nitrobenzo-2-oxa-1, 3-diazole), a variable extent of inhibition was observed for αI346 and αI348 mutants. MgPi protection against NBD-Cl induced inhibition of wild-type, αI346, and αI348 demonstrated that, although strongly conserved, αI346 and αI348 have no direct role in phosphate binding. Insertion of Arginine in the form of αI346R/ßR182A, αI346R/αR376A, or αI348R/ßR182A was able to compensate for the absence of known phosphate-binding Arginine residues ßR182 and αR376. Results also suggest that αIle-346 and αIle-348 seem to have functional importance in upholding the phosphate-binding subdomain and transition state stabilization in the catalytic sites of E. coli ATP synthase.

Active recall strategies associated with academic achievement in young adults: A systematic review.

BACKGROUND: Effective learning strategies are crucial to the development of academic skills and information retention, especially in post secondary education where increasingly complex subjects are explored. Active recall-based strategies have been identified as particularly effective for long-term learning. This systematic review investigates the effectiveness of various active recall-based learning strategies for improving academic performance and self-efficacy in higher education students. METHODS: A systematic review of peer-reviewed articles was conducted with a priori criteria by searching PubMed, ScienceDirect, JSTOR, PsycInfo, and Web of Science databases. Search results were screened/extracted and reconciled by two independent authors with the use of a piloted screening tool. Included studies were assessed for quality and risk of bias using the GRADE Quality Assessment Tool for Quantitative Studies. Three overarching study strategies were extracted for further investigation including flashcards, practice testing or retrieval practice, and concept mapping. Within each category, three additional unique search strings were searched, screened, and extracted. A qualitative analysis of the studies was provided. RESULTS: Among the appraised articles, flashcards were found to be popular and correlated with higher GPA and test scores. Self-testing, retrieval practice, and concept mapping were also effective but under-utilized. Concept mapping was found to boost student confidence. CONCLUSION: Active recall strategies exhibit promise for effective learning and additional research in these developing field can support academic pursuits.

A connection between antimicrobial properties of venom peptides and microbial ATP synthase.

Venom peptides anoplin, cupiennin 1a, latarcin 1, latarcin 3a, latarcin 5, melittin, and pandinin 2 are known to have antibacterial properties. In the current study, we examined whether the antimicrobial properties of these venom peptides have any connection to the binding and inhibition of bacterial ATP synthase. Venom peptides inhibited Escherichia coli wild type and mutant membrane-bound F1Fo ATP synthase to varying degrees. Although significant loss of oxidative phosphorylation was observed for wild type, very little loss occurred for null and mutant E. coli strains in the presence of venom peptides. This study also reaffirms that ßDELSEED-motif residues of ATP synthase are required for peptide binding. Modified venom peptides with C-terminal amide (NH2) groups caused augmented inhibition of ATP synthase and E. coli cell death. Growth patterns of wild type, null, and mutant strains in the presence of melittin, anoplin, cupiennin 1a, latarcin 1, latarcin 3a, latarcin 5, pandinin 2, and their modified variants suggested the possibility of additional molecular targets. Our results demonstrate that the antimicrobial properties of venom peptides are connected to the binding and inhibition of bacterial ATP synthase. Moreover, selective inhibition of ATP synthase by venom peptides suggests a viable alternative to combat antibiotic-resistant microbial infections.