Determination of phosphorylation sites in microtubule associated protein MAP65-1

Enhanced UV-B radiation affects AUR1 regulation of mitotic spindle morphology leading to aberrant mitosis

Enhanced UV-B radiation can lead to a variety of stress responses, including effects on cell cycle regulation and mitosis. Aurora kinases are part of the serine/threonine kinase family and play important roles in cell cycle regulation and mitosis. We hypothesize that there may be a connection between these two processes. In this study, the dynamics of chromosomal (H2B-YFP) and AUR1-GFP changes after enhanced UV-B radiation were observed using confocal microscopy, and gene and protein expression patterns under UV-B stress were quantified using RT-qPCR and Western blotting techniques. We analyzed the responses of the AUR1 overexpression to UV-B stress. We measured maximum quantum yield of photosystem Ⅱ as a proxy for UV-B stress. The recovery capacity of AUR1 overexpression strains was analyzed. In our research, we observed that enhanced UV-B radiation affects the subcellular positioning of AUR1, resulting in abnormalities in the positioning and location of the spindle at the poles, which ultimately affects the separation of chromosomes, resulting in "partition-bundle division" and the incorrect direction of division. At the same time, our results also indicated that low-dose UV-B can induce the expression of AUR1, and this overexpression of AUR1 can alleviate the damage caused by UV-B radiation. In summary, the results of our study show that enhanced UV-B radiation can change the activity and expression of AUR1, which is one of the causes of abnormal chromosome segregation. AUR1 participates in the response to UV-B stress, and, to a certain extent, can improve the UV-B tolerance of plants.

Proteins immunologically related to MAP65-1 accumulate and localize differentially during bud development in Vitis vinifera L

Various arrays of microtubules are present throughout the plant cell cycle and are involved in distinct functions. Microtubule-associated proteins (MAPs) regulate microtubule dynamics by acting as stabilizers, destabilizers, and promoters of microtubule dynamics. The MAP65 family is a specific group of cross-linkers required for structural maintenance of microtubules. In plants, different isoforms of MAP65 are differentially expressed according to their developmental program. In this work, we analyzed the differential distribution of proteins immunologically related to MAP65-1 during bud development in grapevine (Vitis vinifera L.). First, we annotated the MAP65 genes present in the Vitis genome in order to compare the number and sequence of genes to other species. Subsequently, we focused on a specific isoform (MAP65-1) by characterizing its accumulation and distribution. Proteins were extracted from different organs of Vitis (buds, leaves, flowers, and tendrils), were separated by two-dimensional electrophoresis (2-DE), and were probed by immunoblot with a specific antiserum. We found seven spots immunologically related to MAP65-1, grouped in two distinct clusters, which accumulate differentially according to the developmental stage. In addition, we analyzed the localization of MAP65-1 during three different stages of bud development. Implication of data on the use of different isotypes of MAP65-1 during Vitis development is discussed.