Another building block in the plant cell wall: Barley xyloglucan xyloglucosyl transferases link covalently xyloglucan and anionic oligosaccharides derived from pectin

• DOI: 10.1111/tpj.14964
• Publication Date: 2020-08-16T09:41:40Z
• Authors: Barbora Stratilová; Sergej Šesták; Jozef Mravec; Soňa Garajová; Zuzana Pakanová; Kristína Vadinová; Danica Kučerová; Stanislav Kozmon; Julian G. Schwerdt; Neil Shirley; Eva Stratilová; Maria Hrmova
• Keywords: Xyloglucan

SUMMARY We report on the homo‐ and hetero‐transglycosylation activities of HvXET3 HvXET4 xyloglucan xyloglucosyl transferases (XET; EC 2.4.1.207) from barley ( Hordeum vulgare L.), visualisation these in young roots using Alexa Fluor 488‐labelled oligosaccharides. discover that isozymes catalyse transglycosylation reactions with chemically defined donor acceptor substrates, specifically penta‐galacturonide [α(1‐4)GalA p ] 5 – homogalacturonan (pectin) fragment. This activity is supported by 3D molecular models docked XXXG substrates at −4 to +5 subsites active sites. Comparative sequence analyses isoforms seed‐localised TmXET6.3 nasturtium Tropaeolum majus L.) permitted engineering mutants could reaction xyloglucan/[α(1‐4)GalA substrate pair, while wild‐type lacked this activity. Expression data obtained real‐time quantitative polymerase chain HvXET transcripts a clustered heatmap expression profiles gene family revealed HvXET6 co‐expressed but did not share monophyletic origin. Conversely, shared relationship, when we examined evolutionary history 419 glycoside hydrolase 16 members, spanning monocots, eudicots basal Angiosperm. The discovered pair discussed against background roles xyloglucan‐pectin heteropolymers how they may participate spatial patterns cell wall formation re‐modelling, affect structural features walls.