Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.4.4 (kinesin)
 5,033 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The involvement of kinesin motor proteins in both cell-tip growth and cell-shape determination has been well characterized in various organisms. However, the functions of kinesins during cell morphogenesis in higher plants remain largely unknown. In the current study, we demonstrate that an armadillo repeat-containing kinesin-related protein, ARMADILLO REPEAT KINESIN1 (ARK1), is involved in root-hair morphogenesis. Microtubule polymers are more abundant in ark1 null allele root hairs, but analysis shows that these extra microtubules are concentrated in the endoplasm, and not in the cortical array, suggesting that ARK1 regulates tip growth by limiting the assembly and distribution of endoplasmic microtubules. The ARK1 gene has two homologues in the Arabidopsis genome, ARK2 and ARK3, and our results show that ARK2 is involved in root-cell morphogenesis. We further reveal that a NIMA-related protein kinase, NEK6, binds to the ARK family proteins and has pleiotropic effects on epidermal-cell morphogenesis, suggesting that NEK6 is involved in cell morphogenesis in Arabidopsis via microtubule functions associated with these armadillo repeat-containing kinesins. We discuss the function of NIMA-related protein kinases and armadillo repeat-containing kinesins in the cell morphogenesis of eukaryotes.
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PMID:Armadillo repeat-containing kinesins and a NIMA-related kinase are required for epidermal-cell morphogenesis in Arabidopsis. 1797 Oct 38

Aucsia is a green plant gene family encoding 44-54 amino acids long miniproteins. The sequenced genomes of most land plants contain two Aucsia genes. RNA interference of both tomato (Solanum lycopersicum) Aucsia genes (SlAucsia-1 and SlAucsia-2) altered auxin sensitivity, auxin transport and distribution; it caused parthenocarpic development of the fruit and other auxin-related morphological changes. Here we present data showing that the Aucsia-1 gene of Arabidopsis thaliana alters, by itself, root auxin biology and that the AtAUCSIA-1 miniprotein physically interacts with a kinesin-related protein. The AtAucsia-1 gene is ubiquitously expressed, although its expression is higher in roots and inflorescences in comparison to stems and leaves. Two allelic mutants for AtAucsia-1 gene did not display visible root morphological alterations; however both basipetal and acropetal indole-3-acetic acid (IAA) root transport was reduced as compared with wild-type plants. The transcript steady state levels of the auxin efflux transporters ATP BINDING CASSETTE subfamily B (ABCB) ABCB1, ABCB4 and ABCB19 were reduced in ataucsia-1 plants. In ataucsia-1 mutant, lateral root growth showed an altered response to i) exogenous auxin, ii) an inhibitor of polar auxin transport and iii) ethylene. Overexpression of AtAucsia-1 inhibited primary root growth. In vitro and in vivo protein-protein interaction experiments showed that AtAUCSIA-1 interacts with a 185 amino acids long fragment belonging to a 2712 amino acids long protein of unknown function (At4g31570). Bioinformatics analysis indicates that the AtAUCSIA-1 interacting protein (AtAUCSIA-1IP) clusters with a group of CENP-E kinesin-related proteins. Gene ontology predictions for the two proteins are consistent with the hypothesis that the AtAUCSIA-1/AtAUCSIA-1IP complex is involved in the regulation of the cytoskeleton dynamics underlying auxin biology.
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PMID:Arabidopsis thaliana AUCSIA-1 regulates auxin biology and physically interacts with a kinesin-related protein. 2291 80

Cytokinesis in plants involves the formation of unique cellular structures such as the phragmoplast and the cell plate, both of which are required to divide the cell after nuclear division. In order to isolate genes that are involved in de novo cell wall formation, we performed a large-scale, microscope-based screen for Arabidopsis mutants that severely impair cytokinesis in the embryo. We recovered 35 mutations that form abnormally enlarged cells with multiple, often polyploid nuclei and incomplete cell walls. These mutants represent seven genes, four of which have previously been implicated in phragmoplast or cell plate function. Mutations in two loci show strongly reduced transmission through the haploid gametophytic generation. Molecular cloning of both corresponding genes reveals that one is represented by hypomorphic alleles of the kinesin-5 gene RADIALLY SWOLLEN 7 (homologous to tobacco kinesin-related protein TKRP125), and that the other gene corresponds to the Arabidopsis FUSED ortholog TWO-IN-ONE (originally identified based on its function in pollen development). No mutations that completely abolish the formation of cross walls in diploid cells were found. Our results support the idea that cytokinesis in the diploid and haploid generations involve similar mechanisms.
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PMID:A Genetic Screen for Mutations Affecting Cell Division in the Arabidopsis thaliana Embryo Identifies Seven Loci Required for Cytokinesis. 2674 75

The mechanisms by which molecular motors associate with specific cargo is a central problem in cell organization. The kinesin-like protein Smy1 of budding yeast was originally identified by the ability of elevated levels to suppress a conditional myosin-V mutation (myo2-66), but its function with Myo2 remained mysterious. Subsequently, Myo2 was found to provide an essential role in delivery of secretory vesicles for polarized growth and in the transport of mitochondria for segregation. By isolating and characterizing myo2 smy1 conditional mutants, we uncover the molecular function of Smy1 as a factor that enhances the association of Myo2 with its receptor, the Rab Sec4, on secretory vesicles. The tail of Smy1-which binds Myo2-its central dimerization domain, and its kinesin-like head domain are all necessary for this function. Consistent with this model, overexpression of full-length Smy1 enhances the number of Sec4 receptors and Myo2 motors per transporting secretory vesicle. Rab proteins Sec4 and Ypt11, receptors for essential transport of secretory vesicles and mitochondria, respectively, bind the same region on Myo2, yet Smy1 functions selectively in the transport of secretory vesicles. Thus a kinesin-related protein can function intimately with a myosin-V and its receptor in the transport of a specific cargo.
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PMID:Kinesin-related Smy1 enhances the Rab-dependent association of myosin-V with secretory cargo. 2730 83

Phragmoplast-associated kinesin-related protein 2 (PAKRP2) is an orphan kinesin in Arabidopsis thaliana that is thought to transport vesicles along phragmoplast microtubules for cell plate formation. Here, using single-molecule fluorescence microscopy, we show that PAKRP2 is the first orphan kinesin to exhibit processive plus-end-directed motility on single microtubules as individual homodimers. Our results show that PAKRP2 processivity is achieved despite having an exceptionally long (32 residues) neck linker. Furthermore, using high-resolution nanoparticle tracking, we find that PAKRP2 steps via a hand-over-hand mechanism that includes frequent side steps, a prolonged diffusional search of the tethered head, and tight coupling of the ATP hydrolysis cycle to the forward-stepping cycle. Interestingly, truncating the PAKRP2 neck linker to 14 residues decreases the run length of PAKRP2; thus, the long neck linker enhances the processive behavior. Based on the canonical model of kinesin stepping, such a long neck linker is expected to decrease the processivity and disrupt the coupling of ATP hydrolysis to forward stepping. Therefore, we conclude that PAKRP2 employs a noncanonical strategy for processive motility, wherein a long neck linker is coupled with a slow ATP hydrolysis rate to allow for an extended diffusional search during each step without sacrificing processivity or efficiency.
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PMID:The Orphan Kinesin PAKRP2 Achieves Processive Motility via a Noncanonical Stepping Mechanism. 3090 63

Kinesins constitute a protein superfamily that belongs to the motor protein group. Kinesins move along microtubules to exert their various functions, which include intracellular transportation, mitosis, and cell formation. Kinesins are responsible for the transport of various membrane organelles, protein complexes, mRNA and other material, as well as the regulation of intracellular molecular signal pathways. Cumulative studies have also indicated that kinesins are related to the development of a variety of human diseases. At present, there are 14 subfamilies of the kinesin superfamily (KIFs), comprising 45 members. KIF3 is the most common expression in KIFs. KIF3 is a complex composed of a KIF3A/3B heterodimer and a kinesin-related protein, known as KAP3. These complexes are organelles and protein complexes involved in membrane binding in various tissues and transport within cells (nerve cells, melanocytes, epithelial cells, etc.). As a member of the KIF3 subfamily, KIF3B is an essential protein that can regulate cell migration, and proliferation and has critical biological functions. During mitosis, KIF3B is responsible for vesicle transport and membrane expansion, thus regulating cell migration. In recent years, more and more attention has been paid to the relationship between KIF3B and the occurrence and development of diseases. This article reviews the recent advances in the study of KIF3B and its related diseases.
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PMID:Research progress on KIF3B and related diseases. 3170 Sep 28

Orphan and conventional kinesin dimers represent two families of the kinesin superfamily molecular motors. Conventional kinesin, having a 14-residue neck linker (NL) in each head, can step processively on microtubule (MT), with an ATP hydrolysis being coupled with a mechanical stepping under no load. Orphan kinesin phragmoplast-associated kinesin-related protein 2 (PAKRP2) dimer, despite having a NL of 32 residues in each head, can also step processively on MT and exhibits tight chemomechanical coupling under no load. However, the dynamic properties of the wild type PAKRP2 and the mutant one with each NL truncated to 14 residues are very different from those of the wild type conventional kinesin and the mutant one with each NL being replaced by the 32-residue NL from PAKRP2. Here, based on a common chemomechanical coupling model we study computationally the dynamics of the two families of the kinesin dimers, with the simulated results explaining quantitatively the available experimental data. The large differences in the dynamics between the two families of kinesin dimers arise mainly from different rate constants of NL docking and ATPase activity and different weak affinities of the head in ADP state for MT. The studies indicate that both the orphan kinesin PAKRP2 and conventional kinesin use the same mechanism for processive motility.
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PMID:A common chemomechanical coupling model for orphan and conventional kinesin molecular motors. 3268 33


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