Biology subjects

Kitano, Y.

Publications and source records attributed to Kitano, Y..

3 recordsLinked to original sources

bioRxiv2025

Discovery of a wide variety of α-1,6-cyclized β-1,2-glucan synthases: a new entrance for host-microbe interactions.

-1,6-Cyclized {beta}-1,2-glucans (C{beta}G) are established virulence factors in Xanthomonas, yet functional breadth and distribution of C{beta}Gs in nature have remained unclear. Here, we biochemically identified enzymes synthesizing C{beta}Gs with specific chain lengths, exhibiting potential natural occurrence of various C{beta}Gs. Structural analyses identify subtle variations in a loop, named Loop X, as a key determinant of product size, leading to understanding of the whole picture of the mechanism that controls the sizes. We further demonstrated that C{beta}G composed of 13 glucose units contributes to plant-virulence in Ralstonia pseudosolanacearum, expanding the functional scope of virulence-associated cyclic glucans. Overall, it provides the potential targets for regulating various plant-microbe interactions and also serves as a vital lead to discovering unknown host-microbe interactions with significant potential for agricultural applications.

biochemistry↗

bioRxiv2025

The metabolic ability of swallowtails results in the production of bioactive substances from plant components

Host plant selection may depend on the metabolic system in herbivorous insects. Although oligophagous insects take up specific host plant components, how host plant components and their biological activities are altered through their metabolic systems remains unknown. Here, by examining gene expression of metabolic enzymes and components in the larval frass, we investigated the metabolic ability of Papilio memnon larvae fed with Citrus x paradisi (grapefruit) against host plant components. The gene expression levels of some metabolic enzymes were fluctuated between the larval midgut and the larval fat bodies. Furthermore, the chloroform extract from the larval frass, but not that from grapefruit leaves, inhibited cell viability of human pancreatic cancer cell line, MIA PaCa2. Finally, we identified two chlorophyll catabolites, pheophorbide-a and pyropheophorbide-a, in the larval frass extract. Pyropheophorbide-a reduces cell viability of and induces morphological changes in cells of MIA PaCa2; in addition, pheophorbide-a and pyropheophorbide-a inhibit the aggregation of amyloid {beta}-protein (human, 1-42). Therefore, the chemical structure and biological activity of host plant components are affected by the P. memnon metabolic system. Our findings may contribute to the development of a bioprocess for the production of pheophorbide-a and pyrophephorbide-a from chlorophyll via the metabolic functions of P. memnon larvae.

biochemistry↗

bioRxiv2024

Beta-Glucanase superfamily identified by sequential, functional, and structural analyses

{beta}-1,2-Glucans are natural glucose polymers that play important physiological roles, including as symbiotic or pathogenic factors and in osmoregulation. Phylogenetically new glycoside hydrolase (GH) families have recently been identified from {beta}-1,2-glucanase (SGL) sequences from bacteria (GH144) and a fungus (GH162). In this study, we identified four phylogenetically new groups (Groups 1-4), and determined that these families, together with GH144, GH162, and GH189, a family of transglycosylase domains in cyclic {beta}-1,2-glucan synthases, form a superfamily. Biochemical analysis of six proteins in these groups revealed that the proteins in Groups 1-3 showed hydrolytic activity specific to {beta}-1,2-glucan. The kinetic parameters of the enzymes of Groups 1-3 were similar to GH144 and GH162 SGLs, indicating that these enzymes were SGLs. Optical rotation analysis revealed that the SGLs followed an anomer-inverting mechanism. Structural analysis and prediction of the proteins in Groups 1-4, GH144, GH162, and GH189 suggested that Groups 1-3 and GH144 had the same reaction mechanism. Nevertheless, Groups 1-3 were dispersed irregularly in the superfamily. Overall, we determined that Groups 1-3 were new GH families, GHxxx, GHyyy, and GHzzz, respectively, and proposed that this superfamily be called an SGL superfamily because of the phylogenetical, functional, and structural relationships within the superfamily. HighlightsWide variety of glycoside hydrolases is far beyond our understanding. Functional and structural analysis identified three new glycoside hydrolase families. Molecular evolution with irregular changes in reaction mechanism was revealed.

biochemistry↗