Motor proteins not actively involved in transporting cargoes should remain inactive at sites of cargo loading to save energy and remain available for loading. KIF1A/ Unc104 is a monomeric kinesin known to dimerize into a processive motor at high protein concentrations. However, the molecular mechanisms underlying monomer stabilization and monomer-to-dimer transition are not well understood. Here, we report an intramolecular interaction in KIF1A between the forkhead-associated (FHA) domain and a coiled-coil domain (CC2) immediately following the FHA domain. Disrupting this interaction by point mutations in the FHA or CC2 domains leads to a dramatic accumulation of KIF1A in the periphery of living cultured neurons and an enhancement of the microtubule (MT) binding and self-multimerization of KIF1A. In addition, point mutations causing rigidity in the predicted flexible hinge disrupt the intramolecular FHA-CC2 interaction and increase MT binding and peripheral accumulation of KIF1A. These results suggest that the intramolecular FHA-CC2 interaction negatively regulates KIF1A activity by inhibiting MT binding and dimerization of KIF1A, and point to a novel role of the FHA domain in the regulation of kinesin motors.
Introduction. D-alanine:D-alanine ligase (Ddl) catalyses the dimerization of D-alanine before its incorporation in peptidoglycan precursors. The synthesis of D-alanine:Dalanine begins with an attack on the first D-alanine by the ␥-phosphate of adenosine triphosphate (ATP) to yield an acylphosphate. That is followed by attack by the amino group of the second D-alanine, which eliminates the phosphate and produces the D-alanine: D-alanine dipeptide.
In Gram-negative bacteria, proper placement of the FtsZ ring, mediated by nucleoid occlusion and the activities of the dynamic oscillating Min proteins MinC, MinD and MinE, is required for correct positioning of the cell division septum. MinE is a topological specificity factor that counters the activity of MinCD division inhibitor at the mid-cell division site. Its structure consists of an anti-MinCD domain and a topology specificity domain (TSD). Previous NMR analysis of truncated Escherichia coli MinE showed that the TSD domain contains a long α-helix and two anti-parallel β-strands, which mediate formation of a homodimeric α/β structure. Here we report the crystal structure of full-length Helicobacter pylori MinE and redefine its TSD based on that structure. The N-terminal region of the TSD (residues 19–26), previously defined as part of the anti-MinCD domain, forms a β-strand (βA) and participates in TSD folding. In addition, H. pylori MinE forms a dimer through the interaction of anti-parallel βA-strands. Moreover, we observed serial dimer–dimer interactions within the crystal packing, resulting in the formation of a multimeric structure. We therefore redefine the functional domain of MinE and propose that a multimeric filamentous structure is formed through anti-parallel β-strand interactions.
Introduction. Peptidoglycan biosynthesis is initiated with the formation of UDP-N-acetylmuramic acid via the stepwise action of two enzymes, UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) and UDP-N-acetylenolpyruvylglucosamine reductase (MurB), which has proven to be attractive targets for the development of antimicrobial agents. MurA catalyzes the first stage of the reaction, transferal of the enolpyruvate moiety of phosphoenolpyruvate to the 3 0 -hydroxyl of UDP-N-acetylglucosamine with the release of inorganic phosphate. 1 The resulting intermediate, enolpyruvyl-UDP-N-acetylglucosamine (EP-UDPGlcNAc), then undergoes a reduction catalyzed by MurB, which utilizes one equivalent of nicotinamide adenine dinucleotide phosphate and a solvent-derived proton. The reduced product, UDP-N-acetlymuramic acid, can then serve as the locus of attachment for the peptide portion of the cell wall. The resulting pentapeptide then participates in the crosslinking that gives the cell wall its rigidity. 2 Mur enzymes have been well-studied, 2 and the structures of MurA-G have been solved. [3][4][5][6][7][8] Moreover, the structures of MurB have been classified into two types based on the presence or absence of various secondary structural elements and on how these structural elements interact with substrates. For instance, Escherichia coli 4 MurB is classified as Type I and contains a Tyr loop and split babb fold, whereas Staphylococcus aureus 9 MurB is classified as Type II and lacks these secondary elements. Here, we report the crystal structures of Thermus caldophilus MurB, which is also classified as Type II. This is the first report describing the substrate bound structure of a Type II MurB.
Although protein–protein interactions (PPIs) have emerged as the basis of potential new therapeutic approaches, targeting intracellular PPIs with small molecule inhibitors is conventionally considered highly challenging. Driven by increasing research efforts, success rates have increased significantly in recent years. In this study, we analyze the physicochemical properties of 9351 non-redundant inhibitors present in the iPPI-DB and TIMBAL databases to define a computational model for active compounds acting against PPI targets. Principle component analysis (PCA) and k-means clustering were used to identify plausible PPI targets in regions of interest in the active group in the chemical space between active and inactive iPPI compounds. Notably, the uniquely defined active group exhibited distinct differences in activity compared with other active compounds. These results demonstrate that active compounds with regions of interest in the chemical space may be expected to provide insights into potential PPI inhibitors for particular protein targets.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.