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Noncatalytic chalcone isomerase-fold proteins in Humulus lupulus are auxiliary components in prenylated flavonoid biosynthesis.

ABSTRACT: Xanthohumol (XN) and demethylxanthohumol (DMX) are specialized prenylated chalconoids with multiple pharmaceutical applications that accumulate to high levels in the glandular trichomes of hops (Humulus lupulus L.). Although all structural enzymes in the XN pathway have been functionally identified, biochemical mechanisms underlying highly efficient production of XN have not been fully resolved. In this study, we characterized two noncatalytic chalcone isomerase (CHI)-like proteins (designated as HlCHIL1 and HlCHIL2) using engineered yeast harboring all genes required for DMX production. HlCHIL2 increased DMX production by 2.3-fold, whereas HlCHIL1 significantly decreased DMX production by 30%. We show that CHIL2 is part of an active DMX biosynthetic metabolon in hop glandular trichomes that encompasses a chalcone synthase (CHS) and a membrane-bound prenyltransferase, and that type IV CHI-fold proteins of representative land plants contain conserved function to bind with CHS and enhance its activity. Binding assays and structural docking uncover a function of HlCHIL1 to bind DMX and naringenin chalcone to stabilize the ring-open configuration of these chalconoids. This study reveals the role of two HlCHILs in DMX biosynthesis in hops, and provides insight into their evolutionary development from the ancestral fatty acid-binding CHI-fold proteins to specialized auxiliary proteins supporting flavonoid biosynthesis in plants.

SUBMITTER: Ban Z

PROVIDER: S-EPMC5984530 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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Noncatalytic chalcone isomerase-fold proteins in <i>Humulus lupulus</i> are auxiliary components in prenylated flavonoid biosynthesis.

Ban Zhaonan Z Qin Hao H Mitchell Andrew J AJ Liu Baoxiu B Zhang Fengxia F Weng Jing-Ke JK Dixon Richard A RA Wang Guodong G

Proceedings of the National Academy of Sciences of the United States of America 20180514 22

Xanthohumol (XN) and demethylxanthohumol (DMX) are specialized prenylated chalconoids with multiple pharmaceutical applications that accumulate to high levels in the glandular trichomes of hops (<i>Humulus lupulus</i> L.). Although all structural enzymes in the XN pathway have been functionally identified, biochemical mechanisms underlying highly efficient production of XN have not been fully resolved. In this study, we characterized two noncatalytic chalcone isomerase (CHI)-like proteins (desig ...[more]

PMID: 29760092

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Project description:Transcriptional profiling of hop samples throughout in vitro culture on medium with sucrose and hormones IAA and BAP Study of gene expression involved in stress response during in vitro culture and in organogenic nodule formation Hop (Humulus lupulus L.) is an economically important plant forming organogenic nodules which can be used for genetic transformation and micropropagation. We are interested in the mechanisms underlying reprogramming of cells through stress and hormone treatments. To investigate the spatio-temporal sequence of events that underlies competence acquisition for organogenesis three main stages were selected: (i) internodes at the time of excision from the parent plant (T0); (ii) internodes grown for 15 days on culture medium in which several prenodular structures are formed inside the calli (T15d); and (iii) nodule forming tissue after 28 days of culture (T28d). Additionally a control was included corresponding to 28 days of culture without hormones, lacking nodule formation and plantlet regeneration abilities, in order to identify genes specifically involved in morphogenesis (T28dWH). Organogenic nodule formation is a morphogenic process that shares features with somatic embryogenesis though in the former no shoot/root pole is established and plantlet regeneration can occur from different peripheral regions of nodules. Previous studies have shown that the organogenesis-determining period (when cells are determined to form nodules) occurs in between 15 and 25 days of culture corresponding to prenodular and first nodular stages. When nodules are fully developed they are surrounded by layers of elongated, highly vacuolated cells that may degenerate when nodules start differentiating plantlets. Plantlet regeneration from organogenic nodules can be observed after 45 days of culture. However, organogenic nodules after 28 days of culture are already determined to undergo plantlet regeneration, since they no longer require exogenous supply of hormones. Explants cultured in medium without hormones can develop incipient prenodular structures with vascular tissue but not nodules, thus lacking morphogenic potential. Keywords: Plant development, Time course

Dataset Information

Noncatalytic chalcone isomerase-fold proteins in Humulus lupulus are auxiliary components in prenylated flavonoid biosynthesis.

Publications

Noncatalytic chalcone isomerase-fold proteins in <i>Humulus lupulus</i> are auxiliary components in prenylated flavonoid biosynthesis.

Similar Datasets

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